| Nowadays composites play a very important role in engineering from aerospacetechnology and nuclear devices to microelectronics or structural engineering applications.Considering this fact and the growing role of numerical experiments in the designing ofstructures and industrial processes, one of the most important purposes of computationalmechanics research and direction of progress appeared to be precise numerical modelling ofthese materials. Modern computational mechanics of composite materials follows manyvarious ways through different science domains from experimental materials science toadvanced computational techniques and applied mathematics. Commercial computerprograms (such as ABAQUS and ANSYS) based on the Finite Element Method enable nowvisualisation of the multifield, multiphase and non-stationary physical and mechanicalproblems and even introducing uncertainty into computer simulation using random variables.Based on mesomechanics, the mechanical properties and relationship between the constitutematerials of two typical composites (unidirectional fiber reinforced composite and nano rolledstainless steel laminated composites) have been analysed. The following aspects have beenresearched in detail:1. In order to obtain the geometric properties of micro-structural of the fiber (such asarea, eccentricity, spatial distribution and orientation) in the cross section, the transverse SEMpicture of unidirectional fiber reinforced composites is digital processed. Then, script isdeveloped using Python language, which will be called by ABAQUS comfortably. Two typesof fiber random distribution RVE generation method are carried out in the script. One is hardcore algorithm which will be used for low volume content, and the other is two disturbingalgorithm which will be used for high volume content. The transverse stiffness and ultimateload of unidirectional fiber reinforced composites is analysed by using the RVE modelgenerated using two disturbing algorithm.2. The mechanical behaviors of unidirectional fiber reinforced composites consideringinterphase under tensile load are simulated. The interphase is represented by cohesive elementwhich obeys the linear traction-separation law. The effect of thickness, modulus, Poisson rateand strength of interphase on transverse properties of composites is discussed. The resultsindicate that with the decrease of the interphase thickness, the effect of interphase on stiffnessis weak while the effect of interphase on Poisson rateν is strong. The larger the interphasemodulus is, the larger the overall modulus of composites is. The transverse strengt h ofcomposites increases with the increase of interphase strength.3. The tensile damage process of single fiber composite system is simulated bycombination of subroutine USDFLD and UMAT in ABAQUS. Cohesive element is used fordebonding process between fiber and matrix. The results indicate that degradation factor d=0.01is efficient for this type simulation. The effects of constituent materials on the failureof material are significant.4. The cohesive finite element mode l of nano rolled stainless steel laminated compositesis generated by inserting cohesive element in the finite element mesh. The effects of cohesivestrength and energy release rate of nanocrystal material and coarse crystal material on thefailure strain of the composites are studied. The law of microcrack number and damagedisperse energy is realized. In addition, the effect of volume content of nanocrystal materialunder two distribution types on the overall failure of the composites is initially studied.In conclusion, the finite models of two typical composites are generated in the paper.The mechanical response of these materials under tensile load is studied which hopefullywould provide useful reference to the study and design of composites and engineeringapp lication. |
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