Methodology for Impact Modeling of Triaxial Braided

Methodology for Impact Modeling of Triaxial Braided

Composites Using Shell Elements

Xuetao Li 1;Wieslaw K.Binienda 2;and Justin D.Littell 3

Abstract:In this paper,a two-dimensional triaxial braided composite model has been studied using the nonlinear explicit ?nite-element code LSDYNA.The unit cell consists of six subcells and material properties associated with shell element integration point simulate braiding architecture.The local material properties were selected by correlation of the global behavior of a coupon model with static specimen tests.By changing subcell size and orientation angle at integration points,different braids architectures were obtained.Panel ballistic models were performed with bene?ts of computation ef?ciency of shell elements.Mechanical properties,panel impact threshold velocities,and failure initiations for braids with bias angles of 75,60,45,and 30°were studied.Boundary effects were also investigated.DOI:10.1061/?ASCE ?0893-1321?2009?22:3?310?

CE Database subject headings:Impact;Shells;Composite materials;Aerospace engineering .

Introduction

Typical two-dimensional ?2D ?triaxially braided composite archi-tecture is shown in Fig.1.Aerospace applications use textile com-posites,with either woven or braided architecture,because they offer good mechanical and impact performance.Many experi-mental results have demonstrated that braided composites can re-sist crack initiation and propagation as well as formation of delamination during impact ?Roberts et al.2003?.

Due to wide application of this kind of material,the necessity of creating analytical descriptions became evident.Previously,numerous efforts have been made by other researchers to develop analytical tools to predict elastic properties of woven and braided composites.A review of these works may be found in Cheng ?2006?.

In this paper,a unit cell of braided composite was modeled using shell elements.Braiding architecture was obtained using braiding through the integration points ?BTIP ?method.A unit cell was divided into six subcells according to the local ?ber bundle layup,in such a way that each subcell has ?ber bundles laid up without any crossing between each other.Each subcell represents small laminate using available shell element within the explicit FEM code LSDYNA ?LSTC 2004?.Model assumptions,limita-tions,validation process,and prediction results will be presented in the following sections.

Braiding through Integration Points Method

In two-dimensional ?2D ?triaxially braided composite,three dis-tinguished yarns are intertwined to form a single layer of 0°/??°material.Bias bundles undulate over and under each other alternatively,while 0°yarn is straight and de?nes the axial direction of the composite.Speci?cally,if ?=60°?ber architec-ture offers improved resistance than many woven composites as properties are balanced in all directions due to quasi-isotropic nature.In this paper,a composite made of six layers of braid is considered.The composite is made of T700S carbon ?bers and a 5208epoxy resin system,based upon work supported by National Aeronautics and Space Administration ?NASA ?under Award No.NNX07A V60A.The constituent’s properties are shown in Table 1.Axial yarns consist of 24,000?ber tows,and bias yarns use 12,000?ber tows.Furthermore,the total ?ber volume ratio is about 56%.

A convenient way to analyze triaxially braided composite is to focus on a unit cell,which represents complete information about the composite con?guration in the smallest repeating volume.The unit-cell size depends on dimension of ?ber tows,and the mag-nitude of the bias angle.The critical geometry parameters of a unit cell were discussed by Chou and Ko ?1989?.The width of the unit cell,w ,is selected to be twice the braiding space,d .Braiding space is the distance between center line of two neighbored axial ?ber tows.The unit-cell length,l ,could be calculated using bias angle ?and unit-cell width w ,as shown in Eqs.?1?and ?2?.The detailed ?ber architecture is shown in the top view of Fig.2

w =2d ?1?l =d /tan ?

?2?

In order to represent composite architecture using the BTIP method ?Cheng 2006?,an idealized unit-cell con?guration is di-vided into six subcells ?Figs.2and 3?.The cross-section view gives a clear picture of ?ber bundle undulation.We assume that each subcell consists of three or two layers of unidirectional lami-nas.Each local layer is represented in the bottom picture of Fig.3in a different shade.We assume that local layers are of uniform

1

Professor,Univ.of Akron,302Buchtel Common,Akron,OH 44325?corresponding author ?.E-mail:x117@https://www.wendangku.net/doc/837548733.html, 2

Univ.of Akron,302Buchtel Common,Akron,OH 44325.E-mail:wieslaw@https://www.wendangku.net/doc/837548733.html, 3

Univ.of Akron,302Buchtel Common,Akron,OH 44325.E-mail:jdl27@https://www.wendangku.net/doc/837548733.html,

Note.This manuscript was submitted on July 15,2008;approved on January 22,2009;published online on June 15,2009.Discussion period open until December 1,2009;separate discussions must be submitted for individual papers.This paper is part of the Journal of Aerospace Engi-neering ,V ol.22,No.3,July 1,2009.?ASCE,ISSN 0893-1321/2009/3-310–317/$25.00.

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thickness and constant local ?ber volume ratio,which can be signi?cantly higher or lower than the global ?ber volume ratio.Each local laminate is named with capital letters A–F that indicate a different lamination sequence:+60°/0°/?60°,+60°/?60°,?60°/+60°,?60°/0°/+60°,?60°/+60°,and +60°/?60°,re-spectively.Based on the measurements of the braided composite coupon with 0°/?60°architecture,the average unit-cell size is 0.706in.?w ??0.2in.?l ??0.125in.?t ?and Subcells A and D are 0.1654in.?w ??0.2in.?l ??0.125in.?t ?,while each of Subcells B,C,E,and F are 0.0827in.?w ??0.2in.?l ??0.125in.?t ?.In explicit code LSDYNA,it is convenient to model laminated composite with shell elements.Plies of laminated composite cor-respond to the integration points in the thickness direction of the

shell element,so the number of ply is equal to the number of integration points.For example,Subcells A and D have three plies,so corresponding shell elements have three integration points,while Subcells B,C,E,and F have only two integration points at each corresponding shell element.The relative thickness and laminate properties of each ply can be speci?ed individually in the input deck using the *INTEGRATION ?SHELL card.Meanwhile,the ?ber orientation in each ply is represented by the BETA parameter in the *SECTION ?SHELL card.

The individual layer properties of each laminate have to be speci?ed through additional material PART IDs de?ned by the *INTEGRATION ?SHELL card.The following additional as-sumptions are necessary to produce local lamina properties:Since in Subcells A and D three layers have to occupy the same thick-ness as only two layers in the remaining subcells,the local ?ber volume ratio in Subcells A and D should be higher than the ?ber volume ratio in the other subcells.Hence,the individual thickness of each ply and local ?ber volume ratio have to be assumed in such a way so that the global ?ber volume ratio remains 56%,and the ?ber contribution in 0°,?60°,and +60°orientations are equal to satisfy quasi-isotropic composite requirement.Consequently,unidirectional lamina properties will be different in each subcell but each lamina material constant could be calculated through sets of micromechanical equations ?Isaac and Ori 1994?as a function of ?ber volume ratio and mechanical properties of ?ber and resin.Obviously,there are in?nite combinations of unknown local properties for each lamina related to the unknown local ?ber vol-ume ratio.In this paper,we assume that all bias ?ber layers in all subcells have 50%?ber volume ratio,and thickness of those lay-ers in Subcells A and D are half of the axial layers due to the number of ?bers in each bundle.Based on these assumptions the axial layers must have 80%?ber volume ratio.Table 2shows the assumed local ply thicknesses and ?ber volume ratios.Table 3gives local lamina elastic properties calculated using the above assumptions with help of Eqs.?3?–?8??Christensen 1990,2000?.It has been shown experimentally that ?ber yarn tensile strength hinges on numbers of ?bers,and could be expressed by Weibull distribution ?Zhou et al.2001?.Fiber bundle tensile strength be-comes smaller with more ?bers due to local defect distribution and ?ber interaction.Since the bias yarns have only 12k of ?bers and axial yarns have 24k of ?bers,the tensile strength of 0°yarns is assumed to be 50%of the strength of the bias yarns.The localized unidirectional layer strengths were determined by cor-relation of the numerical simulation results with results of the experimental coupon tests

E 1=E f V f +E m V m

?3?

Table 1.Constitution’s Property of Fiber and Resin at Room Tempera-ture

Fiber ?Toray T700s ?a

Epoxy ?5208?b Density ?lb force s 2/in.4? 1.683?10?4 1.265?10?4Young’s modulus ?psi ? 3.336?107

5.60?105

Poisson’s ratio

0.230.42Tensile strength ?psi ?7.107?105

0.73?104

Failure strain ?%? 2.1

1.4

a

See Isaac and Ori ?1994?.b

See Littel et al.?2009?.

Table 2.Fiber V olume Ratio and Thickness of Each Integration Point of Unit Cell

Subcell

0°

?ber tow ?ber volume ratio

?%?

?60°?ber tow ?ber volume ratio

?%?

0°?ber tow thickness ?60°?ber tow thickness A 8050

0.5w 0.25w B N/A

a

50N/A a 0.5w C N/A

a

50N/A a 0.5w D 8050

0.5w 0.25w E N/A

a

50N/A a 0.5w F N/A

a

50N/A a

0.5w

Note:w =thickness of one layer braids.a

N /A=not available.

a)Braided architecture b)Braided model

representation

Fig.1.+60/0/?60triaxially braided composite architecture

[+60o /0o /-60o ]

[-60o /0o /+60o ]

[+60o /-60o ]

[+60o /-60o ]

[-60o /+60o ]

[-60o /+60o

]

d

w Fig.2.Unit-cell con?gurations with 60°bias

angle

Fig.3.Six subcells unit-cell model

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?12=?f 12V f +?m V m ?4?1E 2=V f E f 2+V m

E m ?5?

1G 12=V f G f +V m

G m

?6?G 23=G m

V f +?23?1?V f ?

?23?1?V f ?+V f G m /G f

?7?

?23=

3?4?m +G m /G f

4?1??m ?

?8?

*Mat ?ENHANCED ?COMPOSITE ?DAMAGE material model in

LSDYNA was used in the following validations and further simu-lations ?Melis et al.2004?.Chang/Chang failure criteria ?Hashin 1980?are used.

Tensile ?ber mode

e f

2=

??aa X t

?2

+?

??ab S c

?

2

?1

?aa ?0

when fail,E a =E b =G ab =v ba =v ab =0Compressive ?ber mode

e c

2=

??aa X c

?

2

?1

?aa ?0

when fail,E a =v ba =v ab =0

Tensile matrix mode

e m

2=

??bb

Y t

?2

+

??ab S c ?

2?1

?bb ?0

when fail,E b =v ba =G ab =0

Compressive matrix mode

e d

2=

??bb 2S c

?2

+

??Y c 2S c

?2

?1??bb Y c +

??ab S c

?

2

?1

?bb ?0

when fail,E b =v ab =v ba =G ab =0

where,e f ,e c ,e m ,and e d will be output as each integration point variable for local damage information.When they are posi-tive,it means failed in this mode.

Specimen Test and Model Validation for 60°/0°/?60°Braided Composite

The material mechanical properties in the axial and transverse direction of the triaxially braided composite with 60°bias angles were validated using laboratory tests results.Stress-strain curves were produced for both the standard ASTM straight sided speci-men ?Fig.4?and the bowtie shape specimen ?Fig.5?.We assumed that there is no shift among all six layers used to fabricate this composite.We used Chang-Chang failure criteria to simulate composite material failure behavior ?LSTC 2004?.

Table 3.Material Properties for Integration Points Properties

Unit ?psi ?

0°?ber at Subcells A and C

60°?ber at Subcells A and C

60°?ber at Subcells B and D Young’s modulus,a

Ea 2.78E+07 1.70E+07 1.70E+07Young’s modulus,b

Eb 3.00E+06 1.27E+06 1.27E+06Young’s modulus,c

Ec 3.00E+06 1.27E+06 1.27E+06Poisson’s ratio,ba

vba 0.03480.02470.0247

Poisson’s ratio,ca

vca n/a a

n/a a n/a a Poisson’s ratio,cb

vcb n/a a n/a a n/a a Shear modulus,ab

Gab 9.70E+05 4.00E+05 4.00E+05Shear modulus,bc

Gbc 1.40E+050.530E+050.530E+05Shear modulus,ca

Gca 1.40E+050.53E+050.53E+05Longitudinal compressive strength Xc 1.39E+05 1.39E+05 1.39E+05Longitudinal tensile strength Xt 2.35E+05 4.70E+05 4.70E+05Transverse compressive strength Yc 6.04E+03 6.04E+03 6.04E+03Transverse tensile strength Yt 6.04E+03 6.04E+03 6.04E+03Shear strength Sc 6.82E+03 6.82E+03 6.82E+03

Note:a =direction is corresponding to ?ber longitudinal direction,while b and c =direction in transverse plane.a

n /a=not available.

Lo

L oad

Load

(a

(b)S Ax a)Straight

A

Straight Tran xial fiber direct Axial tensile nsverse

tensi tion

specimen

ile

specimen Axial

fi n

ber

direction

Load

Load

Fig.4.Straight side test specimen dimension

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Specimen Geometries

The straight sided tensile specimen was 12in.by 1.409in.with six layers of preform used in the thickness direction.Axial tests results were produced using specimens with the 0°?bers aligned along the applied load direction.Transverse tests were produced using specimens so 0°?bers are perpendicular to the direction of the applied load ?Fig.4?.The bowtie specimens were designed so all bias ?bers are extended into gripping areas producing V-shape specimens.The dimensions of axial and transverse bowtie speci-mens are shown in Fig.5.Test Results

Stress and strain curves produced by the LSDYNA simulation and experiment test are shown for axial and transverse specimens in Figs.6and 7,respectively.Both straight sided and bowtie speci-men results are included.A summary of the stiffness and strength values are in Table 4.

Bowtie specimens give higher modulus and strength values than straight side specimens.This is due to the fact that in the bowtie specimen more bias angle ?bers could contribute to carry the load.The failure progression at various integration points pro-duces the nonlinear behavior of composite.Local material param-eters are ?ne tuned ?see Table 3?,so LSDYNA simulations are as close to the above experimental results as possible.The differ-ences between corresponding values in Table 4are within 10%.

The simulation of the axial ASTM standard tension specimens shows sudden failure and in all cases a crack was formed near the gripping end.The bowtie specimens failed at the narrowest re-gion.LSDYNA simulations of transverse tensile specimens show that failure is initiated by cracking of the matrix between Subcells B and C or E and F,where only bias ?bers exist.

Table 4.+60°/0°/?60°Braided Composite Material Property Material Tensile direction Test geometry Stiffness ?Msi ?Strength ?ksi ?T700s/5208

Axial bowtie DYNA 10.12125.6TEST 10.69118.7Axial straight DYNA 6.81104.3TEST 6.9695.6Transverse bowtie DYNA 8.37117.9TEST 8.0085.5Transverse straight

DYNA 6.1948.6TEST

5.96

45.5

Fig.5.Bowtie specimen dimension

Axial Tension Test

Strain

0.000

0.002

0.004

0.006

0.008

0.010

0.012

0.014

0.016

0.018

S t r e s s (P S I )

-2.0e+4

0.02.0e+44.0e+46.0e+48.0e+41.0e+51.2e+51.4e+5

Fig.6.Axial tension stress-strain curves ?simulation and test ?of T700s/5208braided composite with 56%?ber volume ratio

Transverse Tensile Test

Strain

-0.0050.0000.0050.0100.0150.0200.025

S t r e s s [P s i ]

0.0

2.0e+44.0e+46.0e+48.0e+41.0e+5

1.2e+51.4e+5

Fig.7.Transverse tension stress-strain curves ?simulation and test ?of T700s/5208braided composite with 56%?ber volume ratio

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Material Properties of Triaxially Braided Composites with Arbitrary Bias Angles

A Braided composite can be fabricated with arbitrary braiding angles besides 60°.Due to limitation of production,braiding angle ?bias angle ?usually ranges from 15to 75°.Let’s assume that local material properties selected in “Specimen Test and Model Validation for 60°/0°/?60°Braided Composite”remain constant and study how the composite behaves if the bias angle is 75,45°or 30°.BTIP methodology can be easily adjusted for other braiding angles,with change of unit-cell geometry.The whole procedure is shown below.Unit-Cell Geometry

It is expected that unit-cell dimension should vary with different braiding angles.Geometry size of unit cell is shown to be affected by ?ber tow cross-sectional dimension and undulation of bias ?bers,etc.Here,in order to capture these factors,a mathematical formula is proposed for unit-cell geometry.Unit-cell width can be calculated using Eq.?9?,incorporating braiding angle ?,widths of

the axial ?ber tows W A ,and bias ?ber tows W B ,respectively.The third term in this equation comes from ?ber yarns undulation,where h =thickness of single layer preform.Similarly to Eq.?2?,the length of the unit cells is de?ned using Eq.?10?

w =2

?

W A 2+W B

cos ?+h cos ??

?9?

l =w

2tan ?

?10?

Using Eqs.?9?and ?10?,the unit-cell dimensions for 30,45,and 75°braids are calculated and presented in Table 5.The unit cell becomes longer and narrower with the braiding angle decreasing as bias ?bers are rotated toward the axial direction.Global Mechanical Properties

The additional axial and transverse straight sided specimen tensile tests were modeled in LSDYNA for 30,45,and 75°braided com-posite;and specimen sizes were chosen similar to the 60°speci-men.From simulation results,there is no difference in failure type among four specimens,while the smaller braiding angle leads to more signi?cant nonlinearity in the transverse tensile test,and induces more signi?cant cross-section contraction in the axial ten-sile specimen.

The stiffness and strength values were pulled out from simu-lations ?see Table 6?.Fig.8is produced by simulating appropriate specimens with various bias angles,and it shows the relationship between mechanical properties and braiding angle.As expected,with a smaller braiding angle,more ?ber contributes to resist axial load,so the axial stiffness and strength increase.At the same time,the mechanical properties in the transverse direction become weaker.

Panel Impact Test

Assuming that mechanical properties of composites with 30,45,60,and 75°braided architectures are determined,we will inves-tigate how structural panels made of these four composites be-have under impact conditions.Model geometry will re?ect experimental setup used for panels with 60°bias angles that were tested at NASA Ballistic Laboratory.An experimental rig sup-

Table 5.Unit-Cell Dimensions for 75,60,45,and 30°Bias Angle Braids Bias angle ?deg ?Width ?in.?Length ?in.?75° 1.17710.157760°0.70450.203445°0.56100.280530°

0.5000

0.4333

Table 6.Triaxially Braided Composite Material Property Bias angle ?deg ?Test direction Stiffness ?Msi ?Strength ?ksi ?75°Axial 4.086.2Transverse 9.062.360°Axial 6.8104.3Transverse 6.248.645°Axial 9.1130.4Transverse 3.634.330°

Axial 13.2164.2Transverse

2.1

19.5

Fig.8.Relationship between composite material properties and braiding angle

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ported 24in.by 24in.?at panels using a steel picture frame with 20in.by 20in.opening as shown in Fig.9.Panels were impacted by a gelatin projectile shown in Fig.10.The projectile is soft to eliminate ?ber cutting and to transfer maximum strain energy to the panel during contact.In LSDYNA,equation of state ?EOS ?has been used for characterization of projectile behavior and an alternative Lagrangian Eulerian ?ALE ?algorithm was used to allow large deformation of the gelatin during impact ?Cheng 2006?.

The LSDYNA model for a panel with 60°bias angle and gela-tin projectile is shown in Fig.11.Again,Chang-Chang stress failure criteria are used so various modes of failure can be nu-merically determined.Element erosion can be triggered by all integration points failure or by effective strain reaching its thresh-old.

In the ?rst numerical study,four panels with 30,45,60,and 75°braiding angles,respectively,were impacted by an identical projectile with the same initial velocity,600ft /s.Under this high velocity,all four panels are penetrated.From the simulation re-sults,failure initiation was the same in each panel due to the matrix tensile https://www.wendangku.net/doc/837548733.html,rmation about status in each layer ?in-tegration point ?can be plotted as a history variable.Fig.12shows plots of local stress in material coordinates,where X denotes the axial ?ber direction and Y the transverse direction,as a function of time,for integration points:1,6,and 12,which correspond to the top,middle,and bottom of the panel,respectively.Material transverse direction is matrix dominated.We can see that the panel fails ?rst under tensile matrix stress at the back side.The whole element was deleted after the effective strain reached 0.11threshold strain.

The initial damage propagates along axial ?bers ?vertical ?and across axial ?bers ?horizontal ?depending on the braid architec-ture.Fig.13shows the failure shapes and V on Misses stress con-tour of four 0.8ms panels at the same time.

Crack propagation depends on the orientation of the bias ?-bers.For example,a crack propagated along the axial bundle at ?rst in the panels with bias angles of 30and 45°.The crack extended faster and was longer in the case of 30°panels,than in the panel with 45°bias angles.As the bias angle became even larger,as it is in the cases of panels with 60and 75°angles,the axial crack was restrained and branches propagated along bias bundles.A butter?y shape crack in the 60°panel was also

ob-24”

20”

Fig.9.Flat panel and picture frame rig ?Courtesy of NASA and the University of Akron

?

5”

2.75”

Fig.10.Gelatin

projectile

Fig.11.Ballistic impact tests simulated by LSDYNA with ALE algorithm

Element in panel center

Time (s)

3e-4

4e-4

4e-4

5e-4

5e-4

6e-4

6e-4

L o c a l Y -S t r e s s (p s i )

02000

4000

6000

8000

Fig.12.Transverse direction stress history in top,middle,and bot-tom layer of panel center

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served in some experimental tests ?Cheng 2006?.From Fig.13,it could be observed that high stresses were more localized in the 60°panel than in the other panels.Meanwhile,the wave propa-gation could also be understood from the contour.The effect of braiding architecture,due to different braiding angles,is clearly shown by these four panel simulations under all assumptions mentioned before.It should be noted that the shape of the propa-gated crack is very sensitive to the mesh size and strength ratio of the axial and bias bundles.If the strength ratio is one,a cross shape crack will be generated in the panel with 60°bias angle.To eliminate some of the assumptions local strengths would need to be determined experimentally.

The other numerical study concentrated on the threshold ve-locity which was de?ned here as the projectile velocity necessary and suf?cient to either cause ?rst integration point failure or de-letion of only one element in the panel.The results of simulations are tabulated in Table 7.

The results of this study show that a panel with a braiding angle of 60°exhibits the highest impact resistance,as de?ned by the largest threshold velocity.One can expect that the panels with 60°bias ?bers have more balanced in-plane stiffness and modulus distribution,which would help delay crack initiation.In the case of other bias angles,the crack initiates and propagates in a rela-tively weak direction.Modeling of cracking progress on braided panels needs further correlation with the test result.As for the case of crack shape analysis,crack initiation and threshold veloc-ity are also in?uenced by the strength ratio between axial and bias

bundles,unit-cell dimensions,and element size.In fact,the trend between magnitudes of threshold velocities for panels with 60,45,and 30°bias angles may be altered if the element size is too big.Hence,the predictions in terms of threshold velocity magni-tudes need to be veri?ed experimentally.

Boundary Effect in Panel Impact

In the previous section on panel impact simulations,all four boundaries were assumed to be ?xed.By comparing simulated results of out-of-plane deformation with the experimentally mea-sured deformation,more realistic boundary conditions are ob-tained if some elastic deformation is allowed at the boundary,even in the case when no slippage or pullout of ?bers from the gripping areas are observed.The change of boundary condition may also lead to an increase of threshold velocity.To investigate the boundary effect we assume stiff springs attached to all four edges that would allow inward elastic deformation while out-of-plane deformation is fully constrained ?see Fig.14?.

We will again study T700s/5208with the 60°bias tows braided panel impacted by a gelatin projectile with an initial pro-jectile velocity of 520ft /s,which is below the penetration veloc-ity according to the test result.This velocity is beyond the predicted penetration velocity of 60°panels shown in Table 7,which means that the material strength veri?ed in the static speci-

Table 7.Panel Impact Threshold Velocity Prediction Bias angle ?deg ?First layer failure

?ft/s ?

First element delete

?ft/s ?

75°28331760°37540445°35037530°

325

354

Fig.13.Failure shape and V on Misses contour of 30,45,60,and 75°

panels

https://www.wendangku.net/doc/837548733.html,posite panels with elastic

boundary

Fig.15.Center point out of plane de?ection comparison

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D o w n l o a d e d f r o m a s c e l i b r a r y .o r g b y H A R B I N

E N G I N E E R I N G U N I V E R S I T Y o n 03/08/16. C o p y r i g h t A S C E .

F o r p e r s o n a l u s e o n l y ; a l l r i g h t s r e s e r v e d .

men test is not high enough to prevent penetration in the impact test.The material strength variation,such as strain effect,could be the reason;this issue could be addressed in future modeling.Here,in order to concentrate on the boundary effect,the compos-ite’s strength values are adjusted ?increased ?as high as to prevent penetration under velocity of 520ft /s,and then three simulations were produced using ?xed boundary conditions,stiff elastic con-ditions,and weak elastic conditions.Simulated deformations are plotted against experimental deformation in Fig.15.

The effect of the boundary can be assessed by investigation of de?ection curves only up to the ?rst dip.Beyond this point damp-ing effects of the material,accumulated damage,possible ?ber pullouts or slippage in the panel,and test rig damping need to be incorporated into the simulations.We can see that with reduction of the in-plane spring stiffness,the maximum out-of-plane de?ec-tion increases.Hence,the elastic boundary reduces the difference between simulation and test results.It is possible that the picture frame rig used in the experimental tests allows some elastic de-?ection in the out-of-plane direction as well.Future experimental measurements will also include deformation measurement at the rig and panel boundary to better characterize boundary conditions of impacted panels.

Conclusion

Braiding through the integration points method is shown to have suf?cient degree of freedom to predict mechanical properties of two-dimensional ?2D ?triaxial braided composite with the shell element based FE https://www.wendangku.net/doc/837548733.html,putational ef?ciency of shell ele-ments makes it feasible to simulate large size panel impact tests.It needs to be acknowledged that proper simulations require guid-ance by experimental results and more results will allow future examination,modi?cation,or correction of many assumptions in-corporated in this study.

Within the scope of this work and incorporated assumptions,the failure initiations,propagation,and various shapes of the crack in panels with different bias braiding angles were predicted,indicating the possibility of the existence of optimal braiding ar-chitecture that can improve performance of the composite struc-tures.The complexity of this problem was also illustrated by the signi?cant change in the magnitude of panel deformation,impact

velocity needed for crack initiation,and shape of propagated cracks in?uenced by the boundary,local strengths,and many other aspects needed to be assumed throughout this analysis.All the assumptions should be experimentally veri?ed as soon as pos-sible.

Acknowledgments

The writers acknowledge support of the National Aeronautics and Space Administration.

References

Cheng,J.Y .?2006?.“Material modeling of strain rate dependent polymer and 2D triaxially braided composites.”Ph.D.dissertation,Univ.of Akron,Akron,Ohio.

Chou,T.W.,and Ko,F.K.?1989?.Textile structural composites ,Elsevier,New York.

Christensen,R.M.?1990?.“A critical evaluation for a class of micro-mechanics models.”J.Mech.Phys.Solids ,38?3?,379–404.

Christensen,R.M.?2000?.“A survey of and evaluation methodology for ?ber composite material failure theories.”Proc.,20th Int.Congress of Theoretical and Applied Mechanics ,Chicago.

Hashin,Z.?1980?.“Failure criteria for unidirectional ?ber composites.”J.Appl.Mech.,31,223–232.

Isaac,M.D.,and Ori,I.?1994?.Engineering mechanics of composite materials ,Oxford University Press,Oxford,U.K.

Littell,J.D.,et al.?2009?.“Characterization of triaxial braided compos-ites using optical measurement techniques,”Am.Antiq.,in press.Livermore Software Technology Corporation ?LSTC ?.?2004?.LS-DYNA keyword user’s manual ,Version 970,Livermore,Calif.

Melis,M.,Carney,K.,Gabrys,J.,Fasanella,E.,and Lyle,K.?2004?.“A summary of the space shuttle Columbia tragedy and the use of LS-DYNA in the accident investigation and return to ?ight efforts.”Proc.,8th Int.LS-DYNA Users Conf.,Dearborn,Mich.

Roberts,G.D.,Pereira,J.M.,Revilock,D.M.,Binienda,W.K.,Xie,M.,and Braley,M.?2003?.“Ballistic impact of composite plates and half-rings with soft projectiles.”Proc.,44th AIAA/ASME/ASCE/AHS Structures,Structural Dynamics,and Materials Conf.,Norfolk,Va.Zhou,Y .X.,Jiang,D.,and Xia,Y .?2001?.“Tensile mechanical behavior of T300and M40J ?ber bundles at different strain rate.”J.Mater.Sci.,36,919–922.

JOURNAL OF AEROSPACE ENGINEERING ?ASCE /JULY 2009/317

D o w n l o a d e d f r o m a s c e l i b r a r y .o r g b y H A R B I N

E N G I N E E R I N G U N I V E R S I T Y o n 03/08/16. C o p y r i g h t A S C E .

F o r p e r s o n a l u s e o n l y ; a l l r i g h t s r e s e r v e d .

的、地、得的用法和区别

“的、地、得”的用法和区别 导入（进入美妙的世界啦~） “的、地、得”口诀儿歌 的地得，不一样，用法分别记心上， 左边白，右边勺，名词跟在后面跑。 美丽的花儿绽笑脸，青青的草儿弯下腰， 清清的河水向东流，蓝蓝的天上白云飘， 暖暖的风儿轻轻吹，绿绿的树叶把头摇， 小小的鱼儿水中游，红红的太阳当空照， 左边土，右边也，地字站在动词前， 认真地做操不马虎，专心地上课不大意， 大声地朗读不害羞，从容地走路不着急， 痛快地玩耍来放松，用心地思考解难题， 勤奋地学习要积极，辛勤地劳动花力气， 左边两人双人得，形容词前要用得， 兔子兔子跑得快，乌龟乌龟爬得慢， 青青竹子长得快，参天大树长得慢， 清晨锻炼起得早，加班加点睡得晚， 欢乐时光过得快，考试题目出得难。 知识典例（注意咯，下面可是黄金部分！） 的、地、得 “的”、“地”、“得”的用法区别本是中小学语文教学中最基本的常识，但在使用中也最容易发生混淆，再加上一段时间里，中学课本中曾将这三个词的用法统一为“的”，因此造成了很多人对它们的用法含混不清进而乱用一通的现象。

一、“的、地、得”的基本概念 1、“的、地、得”的相同之处。 “的、地、得”是现代汉语中高频度使用的三个结构助词，都起着连接作用；它们在普通话中都读轻声“de”，没有语音上的区别。 2、“的、地、得”的不同之处。 吕叔湘、朱德熙所著《语法修辞讲话》认为“的”兼职过多，负担过重，而力主“的、地、得”严格分工。50 年代以来的诸多现代汉语论著和教材，一般也持这一主张。从书面语中的使用情况看，“的”与“地”、“得”的分工日趋明确，特别是在逻辑性很强的论述性、说明性语言中，如法律条款、学术论著、外文译著、教科书等，更是将“的”与“地”、“得”分用。 “的、地、得”在普通话里都读轻声“de”，但在书面语中有必要写成三个不同的字：在定语后面写作“的”，在状语后面写作“地”，在补语前写作“得”。这样做的好处，就是可使书面语言精确化。 二、“的、地、得”的用法 1、的——定语的标记，一般用在主语和宾语的前面。“的”前面的词语一般用来修饰、限制“的”后面的事物，说明“的”后面的事物怎么样。结构形式一般为：形容词、名词（代词）+的+名词。如： ①颐和园(名词)的湖光山色（主语）美不胜收。 ②她是一位性格开朗的女子(名词，宾语)。 2、地——状语的标记，一般用在谓语（动词、形容词）前面。“地”前面的词语一般用来形容“地”后面的动作，说明“地”后面的动作怎么样。结构方式一般为：形容词（副词）+地+动词（形容词）。如： ③她愉快(形容词)地接受(动词，谓语)了这件礼物。 ④天渐渐(时间副词)地冷(形容词，谓语)起来。 3、得——补语的标记，一般用在谓语后面。“得”后面的词语一般用来补充说明“得”前面的动作怎么样，结构形式一般为：动词（形容词）+得+副词。如： ⑤他们玩(动词，谓语)得真痛快(补语)。

常用介词的用法

分考点1 表示时间的介词 Point 1 at, in, on 的用法 （1）at 的用法 At 表示时间点，用于具体的时刻（几点，正午，午夜，黎明，拂晓，日出，日落等），或把某一时间看作某一时刻的词之前以及某些节假日的词之前。 at 6：00 在6点钟 At noon 在中午 At daybreak 在拂晓 At down 在黎明 At Christmas 在圣诞节 【特别注意】在以下的时间短语中，at 表示时间段。 At dinner time 在（吃）晚饭时 At weekends/ the weekend 在周末 （2）in 的用法 ①表示时间段，与表示较长一段时间的词搭配，如年份，月份，季节，世纪，朝代，还可以用于泛指的上午、下午、傍晚等时间段的词前。 In 2009 在2009年 In April 在四月 In the 1990s 在20世纪90年代 In Tang Dynasty 在唐朝 In the morning在上午 ②后接时间段，用于将来时，表示“在一段时间之后”。 The film will begin in an hour. 电影将于一个小时之后开始。 【特别注意】当时间名词前有this，that，last，next，every，each，some等词修饰时，通常不用任何介词。 This morning 今天上午last year 去年 （3）on 的用法 ①表示在特定的日子、具体的日期、星期几、具体的某一天或某些日子。 On September the first 在9月1号 On National Day 在国庆节 We left the dock on a beautiful afternoon. 我们在一个明媚的下午离开了码头。 ②表示在具体的某一天的上午、下午或晚上（常有前置定语或后置定语修饰）。 On Sunday morning 在星期日的早上 On the night of October 1 在10月1号的晚上 【特别注意】“on +名词或动名词”表示“一...就...”. On my arrival home/ arriving home, I discovered they had gone. 我一到家就发现他们已经离开了。 Point 2 in，after 的用法 In 和after都可以接时间段，表示“在...之后”，但in 常与将来时连用，after 常与过去时连用。 We will meet again in two weeks.

英语介词用法大全

英语介词用法大全 TTA standardization office【TTA 5AB- TTAK 08- TTA 2C】

介词（The Preposition）又叫做前置词，通常置于名词之前。它是一种虚词，不需要重读，在句中不单独作任何句子成分，只表示其后的名词或相当于名词的词语与其他句子成分的关系。中国学生在使用英语进行书面或口头表达时，往往会出现遗漏介词或误用介词的错误，因此各类考试语法的结构部分均有这方面的测试内容。 1. 介词的种类 英语中最常用的介词，按照不同的分类标准可分为以下几类： (1). 简单介词、复合介词和短语介词 ①.简单介词是指单一介词。如： at , in ,of ,by , about , for, from , except , since, near, with 等。②. 复合介词是指由两个简单介词组成的介词。如： Inside, outside , onto, into , throughout, without , as to as for , unpon, except for 等。 ③. 短语介词是指由短语构成的介词。如： In front of , by means o f, on behalf of, in spite of , by way of , in favor of , in regard to 等。 (2). 按词义分类 {1} 表地点（包括动向）的介词。如： About ,above, across, after, along , among, around , at, before, behind, below, beneath, beside, between , beyond ,by, down, from, in, into , near, off, on, over, through, throught, to, towards,, under, up, unpon, with, within , without 等。 {2} 表时间的介词。如： About, after, around , as , at, before , behind , between , by, during, for, from, in, into, of, on, over, past, since, through, throughout, till(until) , to, towards , within 等。 {3} 表除去的介词。如： beside , but, except等。 {4} 表比较的介词。如： As, like, above, over等。 {5} 表反对的介词。如： againt ,with 等。 {6} 表原因、目的的介词。如： for, with, from 等。 {7} 表结果的介词。如： to, with , without 等。 {8} 表手段、方式的介词。如： by, in ,with 等。 {9} 表所属的介词。如： of , with 等。 {10} 表条件的介词。如：

of与for的用法以及区别

of与for的用法以及区别 for 表原因、目的 of 表从属关系 介词of的用法 （1）所有关系 this is a picture of a classroom （2）部分关系 a piece of paper a cup of tea a glass of water a bottle of milk what kind of football，American of soccer？ （3）描写关系 a man of thirty 三十岁的人 a man of shanghai 上海人 （4）承受动作 the exploitation of man by man．人对人的剥削。 （5）同位关系 It was a cold spring morning in the city of London in England． （6）关于，对于 What do you think of Chinese food？ 你觉得中国食品怎么样？ 介词 for 的用法小结 1. 表示“当作、作为”。如: I like some bread and milk for breakfast. 我喜欢把面包和牛奶作为早餐。What will we have for supper? 我们晚餐吃什么?

2. 表示理由或原因,意为“因为、由于”。如: Thank you for helping me with my English. 谢谢你帮我学习英语。 Thank you for your last letter. 谢谢你上次的来信。 Thank you for teaching us so well. 感谢你如此尽心地教我们。 3. 表示动作的对象或接受者,意为“给……”、“对…… (而言)”。如: Let me pick it up for you. 让我为你捡起来。 Watching TV too much is bad for your health. 看电视太多有害于你的健康。 4. 表示时间、距离,意为“计、达”。如: I usually do the running for an hour in the morning. 我早晨通常跑步一小时。We will stay there for two days. 我们将在那里逗留两天。 5. 表示去向、目的,意为“向、往、取、买”等。如: let’s go for a walk. 我们出去散步吧。 I came here for my schoolbag.我来这儿取书包。 I paid twenty yuan for the dictionary. 我花了20元买这本词典。 6. 表示所属关系或用途,意为“为、适于……的”。如: It’s time for school. 到上学的时间了。 Here is a letter for you. 这儿有你的一封信。 7. 表示“支持、赞成”。如: Are you for this plan or against it? 你是支持还是反对这个计划? 8. 用于一些固定搭配中。如: Who are you waiting for? 你在等谁? For example, Mr Green is a kind teacher. 比如,格林先生是一位心地善良的老师。

“的、地、得”的用法和区别

的、地、得的用法和区别 的、地、得的用法和区别老班教育 一、的、地、得的基本概念 1、的、地、得的相同之处。 的、地、得是现代汉语中高频度使用的三个结构助词，都起着连接作用；它们在普通话中都读轻声de，没有语音上的区别。 2、的、地、得的不同之处。 吕叔湘、朱德熙所著《语法修辞讲话》认为的兼职过多，负担过重，而力主的、地、得严格分工。50 年代以来的诸多现代汉语论著和教材，一般也持这一主张。从书面语中的使用情况看，的与地、得的分工日趋明确，特别是在逻辑性很强的论述性、说明性语言中，如法律条款、学术论著、外文译著、教科书等，更是将的与地、得分用。 的、地、得在普通话里都读轻声de，但在书面语中有必要写成三个不同的字：在定语后面写作的，在状语后面写作地，在补语前写作得。这样做的好处，就是可使书面语言精确化。 二、的、地、得的用法 （一）、用法 1、的——定语的标记，一般用在主语和宾语的前面。的前面的词语一般用来修饰、限制的后面的事物，说明的后面的事物怎么样。 结构形式一般为：形容词、名词（代词）+的+名词。如： 颐和园(名词)的湖光山色（主语）美不胜收。 她是一位性格开朗的女子(名词，宾语)。 2、地——状语的标记，一般用在谓语（动词、形容词）前面。地前面的词语一般用来形容地后面的动作，说明地后面的动作怎么样。 结构方式一般为：形容词（副词）+地+动词（形容词）。如： 她愉快(形容词)地接受(动词，谓语)了这件礼物。 天渐渐(时间副词)地冷(形容词，谓语)起来。 3、得——补语的标记，一般用在谓语后面。得后面的词语一般用来补充说明得前面的动作怎么样。 结构形式一般为：动词（形容词）+得+副词。如： 他们玩(动词，谓语)得真痛快(补语)。 她红(形容词，谓语)得发紫(补语)。 （二）、例说 的，一般用在名词和形容词的后面，用在描述或限制人物、事物时，形容的词语与被形容的词语之间，表示一种描述的结果。如：漂亮的衣服、辽阔的土地、高大的山脉。结构一般为名词（代词或形容词）+的+名词。如，我的书、你的衣服、他的孩子，美丽的景色、动听的歌曲、灿烂的笑容。 地，用法简单些，用在描述或限制一种运动性质、状态时，形容的词语与被形容的词语之间。结构通常是形容词+地+动词。前面的词语一般用来形容后面的动作。一般地的后面只跟动词。比如高兴地跳、兴奋地叫喊、温和地说、飞快地跑；匆匆地离开；慢慢地移动......... 得，用在说明动作的情况或结果的程度时，说明的词语与被说明的词语之间，后面的词语一般用来补充和说明前面的情况。比如。跑得飞快、跳得很高、显得高雅、显得很壮、馋得直流口水、跑得快、飞得高、走得慢、红得很……得通常用在动词和形容词（动词之间）。

英语介词用法详解

英语常用介词用法与辨析 ■表示方位的介词：in, to, on 1. in 表示在某地范围之内。如： Shanghai is/lies in the east of China. 上海在中国的东部。 2. to 表示在某地范围之外。如： Japan is/lies to the east of China. 日本位于中国的东面。 3. on 表示与某地相邻或接壤。如： Mongolia is/lies on the north of China. 蒙古国位于中国北边。 ■表示计量的介词：at, for, by 1. at表示“以……速度”“以……价格”。如： It flies at about 900 kilometers a hour. 它以每小时900公里的速度飞行。 I sold my car at a high price. 我以高价出售了我的汽车。 2. for表示“用……交换，以……为代价”。如： He sold his car for 500 dollars. 他以五百元把车卖了。 注意：at表示单价(price) ，for表示总钱数。 3. by表示“以……计”，后跟度量单位。如： They paid him by the month. 他们按月给他计酬。 Here eggs are sold by weight. 在这里鸡蛋是按重量卖的。 ■表示材料的介词：of, from, in 1. of成品仍可看出原料。如： This box is made of paper. 这个盒子是纸做的。 2. from成品已看不出原料。如： Wine is made from grapes. 葡萄酒是葡萄酿成的。 3. in表示用某种材料或语言。如： Please fill in the form in pencil first. 请先用铅笔填写这个表格。 They talk in English. 他们用英语交谈(from 。 注意：in指用材料，不用冠词；而with指用工具，要用冠词。请比较：draw in penc il/draw with a pencil。 ■表示工具或手段的介词：by, with, on 1. by用某种方式，多用于交通。如by bus乘公共汽车，by e-mail. 通过电子邮件。

with的用法大全

with的用法大全----四级专项训练with结构是许多英语复合结构中最常用的一种。学好它对学好复合宾语结构、不定式复合结构、动名词复合结构和独立主格结构均能起很重要的作用。本文就此的构成、特点及用法等作一较全面阐述，以帮助同学们掌握这一重要的语法知识。 一、 with结构的构成 它是由介词with或without+复合结构构成，复合结构作介词with或without的复合宾语，复合宾语中第一部分宾语由名词或代词充当，第二部分补足语由形容词、副词、介词短语、动词不定式或分词充当，分词可以是现在分词，也可以是过去分词。With结构构成方式如下： 1. with或without-名词/代词+形容词; 2. with或without-名词/代词+副词; 3. with或without-名词/代词+介词短语; 4. with或without-名词/代词+动词不定式; 5. with或without-名词/代词+分词。 下面分别举例：

1、 She came into the room，with her nose red because of cold.(with+名词+形容词，作伴随状语) 2、 With the meal over ， we all went home.(with+名词+副词，作时间状语) 3、The master was walking up and down with the ruler under his arm。(with+名词+介词短语，作伴随状语。) The teacher entered the classroom with a book in his hand. 4、He lay in the dark empty house，with not a man ，woman or child to say he was kind to me.(with+名词+不定式，作伴随状语) He could not finish it without me to help him.(without+代词 +不定式，作条件状语) 5、She fell asleep with the light burning.(with+名词+现在分词，作伴随状语) 6、Without anything left in the cupboard， she went out to get something to eat.(without+代词+过去分词，作为原因状语) 二、with结构的用法 在句子中with结构多数充当状语，表示行为方式，伴随情况、时间、原因或条件(详见上述例句)。

常用介词用法(for to with of)

For的用法 1. 表示“当作、作为”。如: I like some bread and milk for breakfast. 我喜欢把面包和牛奶作为早餐。 What will we have for supper? 我们晚餐吃什么? 2. 表示理由或原因,意为“因为、由于”。如: Thank you for helping me with my English. 谢谢你帮我学习英语。 3. 表示动作的对象或接受者,意为“给……”、“对…… (而言)”。如: Let me pick it up for you. 让我为你捡起来。 Watching TV too much is bad for your health. 看电视太多有害于你的健康。 4. 表示时间、距离,意为“计、达”。如: I usually do the running for an hour in the morning. 我早晨通常跑步一小时。 We will stay there for two days. 我们将在那里逗留两天。 5. 表示去向、目的,意为“向、往、取、买”等。如: Let’s go for a walk. 我们出去散步吧。 I came here for my schoolbag.我来这儿取书包。 I paid twenty yuan for the dictionary. 我花了20元买这本词典。 6. 表示所属关系或用途,意为“为、适于……的”。如: It’s time for school. 到上学的时间了。 Here is a letter for you. 这儿有你的一封信。 7. 表示“支持、赞成”。如: Are you for this plan or against it? 你是支持还是反对这个计划? 8. 用于一些固定搭配中。如: Who are you waiting for? 你在等谁? For example, Mr Green is a kind teacher. 比如,格林先生是一位心地善良的老师。 尽管for 的用法较多，但记住常用的几个就可以了。 to的用法: 一：表示相对，针对 be strange (common, new, familiar, peculiar) to This injection will make you immune to infection. 二：表示对比，比较 1：以-ior结尾的形容词，后接介词to表示比较，如：superior ,inferior,prior,senior,junior 2: 一些本身就含有比较或比拟意思的形容词，如equal，similar，equivalent，analogous A is similar to B in many ways.

的地得的用法和区分

《“的、地、得”的用法》语文微课教案 一、教学背景 在语言文字规范化大背景下，帮助学生解决应用“的地得”的疑惑与困难。 二、设计思路 针对学生对于“的地得”的误用与忽视展开教学，规范结构助词“的地得”的使用。按照“问题的提出、问题的分析、问题的解决”的思路展开教学，总结归纳优化的方式方法。 三、教学目标 1、知道“怎么样的什么、怎么样地干什么、干得怎么样”三种固定搭配。 2、掌握“的、地、得”的区别与联系。 3、运用小儿歌“动前土、名前白、行动后面双人来”的口诀帮助正确使用“的、地、得”。 四、教学重难点 1、知道“的、地、得”的区别。 2、在实际情境中正确运用“的、地、得”。 五、教学时间 8分钟微课堂 六、教学适用对象 义务教育九年制内的学生 七、教学准备

多媒体课件、录屏软件 八、教学设计与过程 开场白： 同学们好！今天我们一起来学习“的、地、得”的正确用法。首先我们来了解一下它们的区别。 1、相同之处：原来它们都是念轻声“de”，都是结构助词，起连接作用。 2、不同之处：在书面语中要写成三个不同的字，而且它们的搭配及用法也各不相同。 （1）怎么样的什么 （2）怎样样地干什么 （3）干得怎么样 下面我们就来学习一下它们的正确用法。 白勺“的”的结构是用“形容词或名词或代词+的+名词”来表示，而我们最常见，用得最多的还是“形容词+的+名词”的结构。 而土也“地”的用法可以用“形容词+地+动词”的结构来表示。 双人“得”是用“动词+得+形容词”的结构来表示 3、练习巩固 （1）形近区分 静静（的）河面静静（地）写字欢乐（的）山谷

欢乐（地）歌唱满意（地）点头满意（的）作品 （2）类别区分 1）跑（得）飞快飞快（地）跑 2）愉快（的）旅行旅行（得）愉快 3）强烈（的）渴望强烈（地）渴望 （3）综合杂糅 小雏鹰飞到大树的上方，高兴地喊起来：“我真的会飞啦！而且飞（得）很高呢！” 小结：能填对这个句子的你肯定就已经学会它们的用法了！ 4、特殊情况 质疑：假如遇到特殊情况怎么办呢？ 我从书包里拿出书交给她们，她们高兴得．围着我跳起舞来。（出自二年级上册《日记两则》） （1）质疑：为什么这里要使用“得”呢？ （2）释疑：原来这里强调的是心情，动词在后，形容词在前，相当于后置，“得”修饰“跳舞”而非“围”。现在你明白了吧？ 5、小结归纳： 怎么样，你们学会了吗？为了让同学们能够更快的记住它们的用法，老师送给大家一首口诀来帮助你们熟记三个“的”的正确使用方法：动前土、名前白、行动后面双人来。

高中英语45个介词的基本用法

——45个基本介词的用法 1、about 【原始含义】 a-b-out “A在B外面” 【引申含义】 [prep] （1）在…到处，在…各处here and there eg: We wandered about the town for an hour or so. He looked about the room. （2）在…附近next to a place eg. She lives about the office. （3）关于in connection with eg: a book about English study I don’t know what you are talking about. [adv] （1）大约close to eg: We left there about 10 o’clock. It costs about 500 dollars. （2）到处，各处 eg: The children were rushing about in the garden. （3）在附近 eg : There is no food about. 【常见搭配】 作介词时的搭配: 一.动词+(about+名词) （1）arrange (about sth) 安排关于某事（2）argue (about sth) 讨论某事 （3）ask (about sth) 询问关于某事（4）boast (about sb/sth) 吹嘘... （5）care (about sb/sth)关心…,对…感兴趣（6）chat(about sth) 谈论某事（7）complain(about sb/sth) 抱怨… （8）dream (about sb/sth) 梦见某人/某物（9）go (about sth) 着手做...；从事...

with用法归纳

with用法归纳 （1）“用……”表示使用工具，手段等。例如： ①We can walk with our legs and feet. 我们用腿脚行走。 ②He writes with a pencil. 他用铅笔写。 （2）“和……在一起”，表示伴随。例如： ①Can you go to a movie with me? 你能和我一起去看电影'>电影吗？ ②He often goes to the library with Jenny. 他常和詹妮一起去图书馆。 （3）“与……”。例如： I’d like to have a talk with you. 我很想和你说句话。 （4）“关于，对于”，表示一种关系或适应范围。例如： What’s wrong with your watch? 你的手表怎么了？ （5）“带有，具有”。例如： ①He’s a tall kid with short hair. 他是个长着一头短发的高个子小孩。 ②They have no money with them. 他们没带钱。 （6）“在……方面”。例如： Kate helps me with my English. 凯特帮我学英语。 （7）“随着，与……同时”。例如： With these words, he left the room. 说完这些话，他离开了房间。 [解题过程] with结构也称为with复合结构。是由with+复合宾语组成。常在句中做状语，表示谓语动作发生的伴随情况、时间、原因、方式等。其构成有下列几种情形： 1.with+名词(或代词)+现在分词 此时，现在分词和前面的名词或代词是逻辑上的主谓关系。 例如:1)With prices going up so fast, we can't afford luxuries. 由于物价上涨很快，我们买不起高档商品。（原因状语） 2)With the crowds cheering, they drove to the palace. 在人群的欢呼声中，他们驱车来到皇宫。（伴随情况） 2.with+名词(或代词)+过去分词 此时，过去分词和前面的名词或代词是逻辑上的动宾关系。

of和for的用法

of 1....的,属于 One of the legs of the table is broken. 桌子的一条腿坏了。 Mr.Brown is a friend of mine. 布朗先生是我的朋友。 2.用...做成的;由...制成 The house is of stone. 这房子是石建的。 3.含有...的;装有...的 4....之中的;...的成员 Of all the students in this class,Tom is the best. 在这个班级中,汤姆是最优秀的。 5.(表示同位) He came to New York at the age of ten. 他在十岁时来到纽约。 6.(表示宾格关系) He gave a lecture on the use of solar energy. 他就太阳能的利用作了一场讲演。 7.(表示主格关系) We waited for the arrival of the next bus. 我们等待下一班汽车的到来。

I have the complete works of Shakespeare. 我有莎士比亚全集。 8.来自...的;出自 He was a graduate of the University of Hawaii. 他是夏威夷大学的毕业生。 9.因为 Her son died of hepatitis. 她儿子因患肝炎而死。 10.在...方面 My aunt is hard of hearing. 我姑妈耳朵有点聋。 11.【美】(时间)在...之前 12.(表示具有某种性质) It is a matter of importance. 这是一件重要的事。 For 1.为,为了 They fought for national independence. 他们为民族独立而战。 This letter is for you. 这是你的信。

介词with的用法大全

介词with的用法大全 With是个介词，基本的意思是“用”，但它也可以协助构成一个极为多采多姿的句型，在句子中起两种作用；副词与形容词。 with在下列结构中起副词作用： 1.“with+宾语+现在分词或短语”，如： (1) This article deals with common social ills, with particular attention being paid to vandalism. 2.“with+宾语+过去分词或短语”，如： (2) With different techniques used, different results can be obtained. (3) The TV mechanic entered the factory with tools carried in both hands. 3.“with+宾语+形容词或短语”，如： (4) With so much water vapour present in the room, some iron-made utensils have become rusty easily. (5) Every night, Helen sleeps with all the windows open. 4.“with+宾语＋介词短语”，如： (6) With the school badge on his shirt, he looks all the more serious. (7) With the security guard near the gate no bad character could do any thing illegal. 5.“with+宾语＋副词虚词”，如： (8) You cannot leave the machine there with electric power on. (9) How can you lock the door with your guests in? 上面五种“with”结构的副词功能，相当普遍，尤其是在科技英语中。 接着谈“with”结构的形容词功能，有下列五种： 一、“with+宾语+现在分词或短语”，如： (10) The body with a constant force acting on it. moves at constant pace. (11) Can you see the huge box with a long handle attaching to it ? 二、“with+宾语+过去分词或短语” (12) Throw away the container with its cover sealed. (13) Atoms with the outer layer filled with electrons do not form compounds. 三、“with+宾语+形容词或短语”，如： (14) Put the documents in the filing container with all the drawers open.

的地得的用法教案

“的、地、得”的用法教案 教学目标： 1.能通过看视频知道“的、地、得”的用法区别。 2.能在小组合作中正确掌握“的、地、得”的用法。 3.能正确熟练地运用“的、地、得”。 教学重点：通过看视频知道“的、地、得”的用法区别。 教学难点：正确熟练地运用“的、地、得”。 教学过程： 一、导入（板书课题：“的、地、得”的用法“的、地、得”） 这三个字认识吧！虽然它们都有一个相同的读音de，但用法却不一样，可不能把他们用错了。究竟他们的用法有什么不同，我们来听听他们的故事吧！ 二、看微视频，学习“的、地、得”的用法区别。 三、小结： 1.孩子们，刚才看了视频知道他们是谁吗？（白勺的，土也地，双人得。） （1）白勺的是个杂货铺老板，她的店里都有什么？（彩色的毛巾美味的汉堡结实的帐篷舒适的儿童车捕捉风的网会唱歌的小树开个没完的花朵优美动听的歌曲飘来飘去的云……）还可能有什么？ 你们一定会发现，白勺的的用法有什么特点？（后面是名词。）板书：名词 （2）土也地是个运动男孩，他喜欢？（悠闲地散步欢快地跳舞兴奋地跳跃开心地捕蝴蝶看图书踢球骑自行洗澡吃冰淇淋……）他还可能喜欢干什么呢？你发现了吗？土也地的用法特点？（后面是动词。）板书：动词 （3）双人得呢？她是个总喜欢评价别人的小妹妹。（球踢得真棒舞跳得精彩长得好高呀……） 她可能还怎么评价别人？（歌唱得动听饭吃得很饱人长得漂亮）你们会发现，双人得的前面通常都是——动词。板书：动词 2.小结：所以，他们的用法也很简单，区别就在这里。 （白勺的用在名词前面；土也地用在动词前面；双人得用在动词后面。）你明白了吗？ 四、我来考考你们，看哪一组完成得又对又快！ 1.菜鸟级练习 2.老鸟级练习 3.大虾级练习 五、总结

介词at的基本用法

介词at的基本用法： 一、at引导的时间短语通常可表示： 1.在几点几分，例如：at one o’clock(在一点钟) I usually make the bed at one o’clock.. 2.在用餐时间，例如：at lunchtime（在午餐时间） 3.在某个节日，例如：at Christmas 在圣诞节的时候 4.在某个年龄的时候，例如：at the age of 12。在12岁的时候 5.一天中的某段较短的时间，例如：at noon在中午at night在夜里 二、at也可引导地点短语，常用于小地点之前，例如： at the bus stop在汽车站at the butcher’s 在肉店里at school在学校里at home在家里 介词on的基本用法： 一、on可引导地点短语，表示“在…上面”，例如：on the table在桌子上 二、on也可引导时间短语，通常有以下用法： 1.用于“星期”和“月份”中的任何一天之前，例如：On Monday在星期一on April 1st. 2.用于某个“星期几”当天的某段时间，例如：on Monday morning在星期一上午 3.用于具体某一天之前，例如：on that day在那一天On my birthday在我的生日那天 On Christmas day在圣诞节那天 介词in的基本用法： 一、in可引导地点短语，常表示“在…里面”，例如：in the bag在袋子里 二、in引导的时间短于通常有以下用法： 1.在某个世纪，例如：in the 21st century在21世纪 2.在某一年，例如：in 1995在1995年 3.在某一个季节，例如：in spring在春季 4.在某一个月份，例如：in March在三月里 5.在某段时期，例如：in the holidays在假期里 6.在某个持续几天的节日里，例如：in Easter Week在复活周 7.在一天中的某段时间，例如：in the morning在上午（早晨）

初中 英语 介词“with”的用法

介词“with”的用法 1、同, 与, 和, 跟 talk with a friend 与朋友谈话 learn farming with an old peasant 跟老农学习种田 fight [quarrel, argue] with sb. 跟某人打架 [争吵, 辩论] [说明表示动作的词, 表示伴随]随着, 和...同时 change with the temperature 随着温度而变化 increase with years 逐年增加 be up with the dawn 黎明即起 W-these words he left the room. 他说完这些话便离开了房间。2 2、表示使用的工具, 手段 defend the motherland with one s life 用生命保卫祖国 dig with a pick 用镐挖掘 cut meat with a knife 用刀割肉3

3、说明名词, 表示事物的附属部分或所具有的性质]具有; 带有; 加上; 包括...在内 tea with sugar 加糖的茶水 a country with a long history 历史悠久的国家4 4、表示一致]在...一边, 与...一致; 拥护, 有利于 vote with sb. 投票赞成某人 with的复合结构作独立主格,表示伴随情况时，既可用分词的独立结构，也可用with的复合结构： with +名词(代词)+现在分词/过去分词/形容词/副词/不定式/介词短语。例如： He stood there, his hand raised. = He stood there, with his hand raise.他举手着站在那儿。 典型例题 The murderer was brought in, with his hands ___ behind his back A. being tied B. having tied C. to be tied D. tied 答案D. with +名词(代词)+分词+介词短语结构。当分词表示伴随状况时，其主语常常用

for和of的用法

for的用法： 1. 表示“当作、作为”。如: I like some bread and milk for breakfast. 我喜欢把面包和牛奶作为早餐。 What will we have for supper? 我们晚餐吃什么? 2. 表示理由或原因,意为“因为、由于”。如: Thank you for helping me with my English. 谢谢你帮我学习英语。 Thank you for your last letter. 谢谢你上次的来信。 Thank you for teaching us so well. 感谢你如此尽心地教我们。 3. 表示动作的对象或接受者,意为“给……”、“对…… (而言)”。如: Let me pick it up for you. 让我为你捡起来。 Watching TV too much is bad for your health. 看电视太多有害于你的健康。 4. 表示时间、距离,意为“计、达”。如:

I usually do the running for an hour in the morning. 我早晨通常跑步一小时。 We will stay there for two days. 我们将在那里逗留两天。 5. 表示去向、目的,意为“向、往、取、买”等。如: Let’s go for a walk. 我们出去散步吧。 I came here for my schoolbag.我来这儿取书包。 I paid twenty yuan for the dictionary. 我花了20元买这本词典。 6. 表示所属关系或用途,意为“为、适于……的”。如: It’s time for school. 到上学的时间了。 Here is a letter for you. 这儿有你的一封信。 7. 表示“支持、赞成”。如: Are you for this plan or against it? 你是支持还是反对这个计划? 8. 用于一些固定搭配中。如:

高中常见介词的基本用法

介词 介词不能单独作句子成分，而是用来表示名词或代词等和句中其他词的关系，通常放在名词或代词之前，构成介词短语。介词短语作为一个成分在句中可用作定语，表语，状语等。When shall we have the talk on the history of the Party我们何时听党史报告（定语）His elder brother is in the army.他的哥哥在部队。（表语） I went to school at half past seven yesterday.昨天我7：30 上学。（状语） 《 Will you please come along with me跟我一起走好吗（状语） ※同一个汉语词可以译成不同的英语介词。例如： 一幢石头的房子 a house of stone 这个房间的钥匙 the key to this room 明天的票 the ticket for tomorrow 《 （一）About 1．表示地点：在。。。周围；在。。。附近 We took the foreign guests about the campus. 我们带领外宾在校园里各处看看。 2．表示时间：大约。。。；近于。。。时刻前后We left there about six o’clock 我大约在六点左右离开那个地方。 3．表示客体关系：对于；关于；有关。例如：1) I must see him, I’ve heard so much about him 我必须要见他，我听到很多关于他的事情。2) What do you know about China 关于中国你知道些啥 （二）Above 表示位置，职位，数量，年龄等：在。。。上方；在。。。之上；超过。。。 1) Henry’s work is well above the average.亨利的功课大大超过一般水平。 2) A bird is flying above the woods. 一只鸟在树林上飞。 3) The portrait is above the blackboard.一幅肖像挂在黑板的上方。 4) It weighs above five tons. 这东西有5 吨多重。 （三）Across 1．表动作方向/位置：横过；穿过。（在表面）1）The boy helped the old lady across the street. 男孩扶老大娘穿过马路。2) The tree had fallen down across the railway line.树倒啦，横在铁路上。 2．表示地点：在对面；在。。。的另一边。 1）The church is across the river. 教堂在河的对面。 （四）After 1.表示时间或位置：在。。。之后。 1）Please line up one after another. 请一个挨一个排好对。 He goes on working day after day ,week after week without any change. 他继续日复一日地工作，没有丝毫改变。Shut the door after you. 随手关门！ 2．引伸意义：仿照；按照。 Please make sentences after the model. 请照示例造句。 ※（五）Against 1．表示位置：依着；紧靠；撞击；碰着。 1) He rested his bike against the wall.他把自行车靠在墙上。 2) The rain was beating against the windows. 雨敲打着窗户。 2．引伸意义：反对；禁止。 1）Are you for it or against it 你是赞成还是反对 2) Is there a law in this country against spitting right and left 你们国家有没有反对随地吐痰的规定