Weaving and mechanical properties test of polylactic acid/ramie composite fabric

In view of the weak mechanical properties of polylactic acid fiber, the excellent mechanical properties of ramie fiber are selected to enhance the performance of polylactic acid fiber, thereby forming a composite fabric, and weaving plain weave fabric, twill weave fabric, satin weave fabric and square plain fabric by weaving method., Twill change fabric and satin change fabric six kinds of fabrics. Electronic thickness meter, electronic strength meter, and electronic bursting tester were used to test the thickness, tensile fracture and burst performance of 6 kinds of fabrics, and the reasons for the differences between the fabrics were discussed. The research results show that the mechanical properties of composite fabrics are better than those of pure polylactic acid fabrics. In addition, in terms of tensile fracture performance, the satin weave fabric is the strongest, and the satin weave is the strongest in burst performance. In terms of fabric thickness, the lowest thickness value is plain weave, but the thickness value, tensile breaking and bursting properties of square flat fabrics are ranked second, so the overall performance is always the strongest.

HYBRID EXPERIMENTAL AND NUMERICAL CHARACTERIZATION OF THE 3D RESPONSE OF WOVEN POLYMER MATRIX COMPOSITES

The need for advanced material models to simulate the deformation, damage, and failure of polymer matrix composites under impact conditions is becoming critical as these materials are gaining increased usage in the aerospace and automotive industries. The purpose of this work is to characterize carbon epoxy fabrics for composite material models that rely on a large number of input parameters to define their nonlinear and 3D response; e.g. elastic continuum damage mechanics models or plasticity damage models [1, 2]. It is challenging to obtain large sets of experimental stress-strain curves, therefore, careful selection of physical experiments that exhibit nonlinear behavior is done to significantly reduce the cost of generating threedimensional material databases. For this work, plain weave carbon fabrics with 3k and 12k tows are manufactured by VARTM. Testing is done using MTS hydraulic test frames and 2D digital image correlation (DIC) to obtain experimental stress-strain curves for in-plane tension and shear as well as transverse shear. For cases where actual experimental data is either not available or difficult to obtain, the required model input is virtually generated using the NASA Glenn developed Micromechanics Analysis Method/Generalized Method of Cells (MAC/GMC) code. A viscoplastic polymer model is calibrated and utilized to model the matrix constituent within a repeating unit cell (RUC) of a plain weave carbon fiber fabric. Verification and validation of this approach is done using MAT213, a tabulated orthotropic material model in the finite element code LS-DYNA, which relies on 12 input stress-strain curves in various coordinate directions [2]. Based on the model input generated by the micromechanics analyses in combination with available experimental data, a series of coupon level verification and validation analyses are carried out using the MAT 213 composite model.

Experimental Study on Fabrication and Comparison of Mechanical Properties of Plain Weave Copper Mesh Embedded Hybrid Composite with E-Glass Fiber Reinforced Epoxy GFRP Composite

The present research is conducted on GFRP (Glass-Fiber Reinforced Plastic) composite which is fiberglass reinforced with epoxy matrix and find its mechanical properties that can be compared with other hybrid composite which include plain weave copper strips mesh in between the layers of fiberglass in GFRP composite. Both type of composites are made using hand layup technique i.e., placing of chopped fiberglass sheet and then epoxy resin layer by layer, after filling of epoxy and fiberglass at 20% fiber loading which is measured by digital scale, then a pressure is also applied on this sandwich. After 24 hours it is ready to be demolded and after 48 hrs. samples was cuts as per ASTM standards then testing was done on both GFRP and Hybrid composites to find their Mechanical & Physical Properties. Results shows improvement as we introduce plain weave copper strips mesh in between the GFRP laminate to make it hybrid.

Effect of Defects on Progressive Failure Behavior of Plain Weave Textile Composites

Various types of internal defects occur during manufacturing and handling of composite materials. It is practically impossible to manufacture composite structures without defects, making it crucial to understand the effect of defects on their failure behavior to maintain structural safety. In this work, the effect of pre-defects on the failure behavior of plain weave textile composites was studied. Unit cell configurations with symmetric, in-phase, and shifted fiber tow arrangements were considered. Inter-laced warp and fill tows and matrix pockets of plain weave unit cells were modeled in three-dimensional finite elements, and cohesive elements were inserted between all bulk elements to account for the fracture modes of the fiber and matrix direction failure of warp and fill tows, matrix pocket failure, and interface failure. Unit cell models containing pre-defects of voids, tow-matrix pocket separation, warp-fill tow separation, and cracks in the warp and fill tows were analyzed, and their effects on progressive failure behavior were investigated in terms of the interaction between fiber tow arrangements and defects. Results indicated that initial failure occurred in matrix-direction failure mode in fill tows, whereas fiber tow-matrix pocket separation was the major failure mode under uniaxial tensile load. Furthermore, failure behavior was found to be highly dependent on the fiber tow arrangement pattern and the location of pre-defects.