Characterization Of Intralaminar And Interlaminar Mechanical Behavior Of Woven Composite Under Different Loading Modes

Nowadays,vehicle lightweight has become more and more urgent under the pressure of energy saving and emission reduction,and as a result of which,composites has received much attention from automobile industry as a substitute of traditional metal material.As a novel material,woven carbon fiber reinforced composite has a lot of advantages such as high specific strength,high specific stiffness,excellent erosion resistance and so on.However,mechanical characterization of this woven composite material still have many problems to be solved which limits its application in automobile industry.This paper takes this material as research object and conducts related research from three aspects.Firstly,experimental characteristics of mechanical response of woven composite are studied in this research.To obtain basic material properties,calibration experiments are conducted in this research,including unidirectional tension,unidirectional compression,in-plane shearing and tensile and compressive intralaminar fracture tests.To further understand the mechanical characteristics of this material,off-angle tension,punch and axial crushing of corrugated plate are conducted and repetitions of all three kinds of experiments are satisfactory which can be served as base for numerical research in next chapter.Secondly,this paper introduces the continuum damage model – MAT261 in LSDYNA and proposed the modeling strategy for characterization of woven composites.For identification of longitudinal and transverse shear fracture toughness,single element simulation are conducted.Besides,another parameter – effective failure strain is also investigated in this research.Afterwards,simulation of 30 degree off-angle tension,punch and crush are conducted in this research with the modeling strategy and results are all reasonable.By adjustment of peak force value in force versus displacement curve obtained from punch simulation,the fracture angle in matrix direction is identified as a reasonable value.In crush simulation,influences of penetration curve,thickness of crush front element,compressive strength and soft parameter on simulation are studied in detail.Finally,interlaminar failure behavior of this woven composite is investigated in this paper.By combination of both experimental and numerical methods,delamination failure of this material is characterized as follows.Firstly,double cantilever beam experiments are conducted to obtain the mode 1 fracture toughness of this material which presents runarrest failure behavior,then both modified beam method and linear fracture mechanics method are adopted to calculate the experimental toughness value.It is found that results from both data reduction methods correlate with each other very well.For mode 2 fracture test,end notched flexure experiments are conducted to obtain mode 2 fracture toughness from both non-precrack and precrack.Results of same specimen from both cases are nearly same with each other which verifies the validity of pre-insert method.Besides,bilinear cohesive zone model is used to conduct simulation of double cantilever beam and end notched flexure experiments,and mechanical responses of both loading modes are predicted successfully.An important conclusion is that two parameters in cohesive zone model – normal and shear failure stresses are influenced by element size in simulation.It is also found that smaller the element size is,the higher the upper boundary of normal and shear failure stress will be.The regulation are summarized in this research,which provides guidance for engineering application.