| Compared with metal materials,composite materials have the characteristics of light weight,wear resistance and corrosion resistance,and are widely used in aerospace,electronic information,automobiles,engineering machinery and other fields.Among them,glass fiber reinforced composites?GFRP?are often used in lightweight impact-resistant structures such as automobile bumpers,building substrates and so on.Because GFRP composites have anisotropic characteristics and the material structures obtained by different preparation methods are quite different,the mechanical behavior and damage evolution under impact load are complicated and changeable.Therefore,it is very important to study their static and dynamic mechanical properties,carry out material dynamic failure analysis and carry out damage model for material selection and impact damage assessment.At the same time,static and dynamic mechanical behavior and impact damage research can also provide basic parameters for material design optimization.In this paper,E-type glass fiber straight yarn is selected as reinforcing fiber,vinyl ester resin is used as matrix and unidirectional continuous GF/VE with glass fiber mass fractions of 55%,60%,65%,70%and 75%respectively is prepared for experimental research.At room temperature,quasi-static uniaxial compression experiments with strain rate of 5×10-44 s-11 were carried out on GF/VE samples of five glass fiber mass fractions using MTS Landmark 370.5 electro-hydraulic servo experimental system.The results show that the failure of GF/VE specimens is brittle failure.Dislocation occurs in the plane at an angle of 45 with the loading axis,and longitudinal splitting occurs along the loading direction.With the increase of the mass fraction of glass fiber,the elastic modulus and the maximum compressive strength of the material are continuously improved while the maximum strain is continuously reduced.At room temperature,dynamic compression experiments with strain rates of about1100s-1?1300s-1?1500s-1?1700s-1?1900s-11 were carried out on GF/VE samples of five glass fiber mass fractions using a Hopkinson pressure bar?SHPB?experimental apparatus.The results show that increasing the glass fiber content will reduce the toughness of the material.The peak stress of the material increases with the increase of strain rate.The stress-strain curve of the specimen with complete failure shows three intervals,corresponding to three stages,namely,matrix compaction hardening stage,elastic stage and yield softening stage.Combined with the dynamic experimental waveform,the relationship between the failure mode of GF/VE and energy absorption at high strain rate is analyzed.At the strain rate of 1300 s-1and 1900 s-1,three kinds of GF/VE failure specimens with glass fiber mass fraction of 55%,65%and 75%are observed by scanning the electron microscopy?SEM?.The dynamic damage evolution mechanism of the material is revealed from the micro level.Finally,the ZWT constitutive model with damage factor is used to fit the experimental data of GF/VE materials with 60%and 70%glass fiber mass fraction before reaching the ultimate stress.The results show that the ZWT constitutive model with damage factor is suitable for the mechanical behavior description of GF/VE materials.Figure[33]table[9]reference[79]... |
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