Diantang Zhang

Stress field distribution of warp-reinforced 2.5D woven composites using an idealized meso-scale voxel-based model

The evaluation of the stress field distribution of warp-reinforced 2.5D woven composites using meso-scale voxel-based model is described. The idealized geometry model is established by using measured parameters from the CT image. Comparison between voxel-based finite element method and experimental measurements is included. The results show that the proposed meso-scale voxel-based method is capable of accurately predicting the mechanical properties of warp-reinforced 2.5D woven composites, validated by the comparison of the initial modulus, max stress as well as the failure modes. Also, the numbers of representative volume element have an important effect on mechanical behaviors of warp-reinforced 2.5D woven composites.

Multi-Scale Modeling of an Integrated 3D Braided Composite with Applications to Helicopter Arm

A study is conducted with the aim of developing multi-scale analytical method for designing the composite helicopter arm with three-dimensional (3D) five-directional braided structure. Based on the analysis of 3D braided microstructure, the multi-scale finite element modeling is developed. Finite element analysis on the load capacity of 3D five-directional braided composites helicopter arm is carried out using the software ABAQUS/Standard. The influences of the braiding angle and loading condition on the stress and strain distribution of the helicopter arm are simulated. The results show that the proposed multi-scale method is capable of accurately predicting the mechanical properties of 3D braided composites, validated by the comparison the stress-strain curves of meso-scale RVCs. Furthermore, it is found that the braiding angle is an important factor affecting the mechanical properties of 3D five-directional braided composite helicopter arm. Based on the optimized structure parameters, the nearly net-shaped composite helicopter arm is fabricated using a novel resin transfer mould (RTM) process.

Experimental and theoretical analysis of failure mechanism of UHMWPE Yarn under transverse cut loading

Abstract This paper is concerned with transverse cut resistant properties of UHMWPE yarns by the methods of experimental and theoretical analysis. Rheological theory of fabric was applied to evaluate relation of stress and strain of UHMWPE yarn, when the UHMWPE yarn is subjected to external cut force. The dynamic response of yarn and the contact volume of yarn and blade in the cutting have been identified to interpret cut failure mechanism of yarn. The experimental results show that yarn structure, blade edge, and test parameters have great influence on cut resistant property of UHMWPE yarn, and which are consistent with the theoretical analysis. It provides a theoretical basis for quantifying the cutting resistance of fabrics.

Cut resistant property of weft knitting structure: a review

Abstract Application fields of cut resistant textile are very wide, such as, workplace, sports, transportation, and military. With the requirement of lightweight and comfortable cut-proof clothes, the knitted fabric has the advantages of its structure, which is more and more widely used. The common four forms of yarn in the knitting structure is held loop, tuck loop, float loop, and free yarn. The cut resistant mechanism of fabric is much more complex, due to their fiber and yarn intrinsic properties and fabric structure. So, cut test of fiber, yarn, and fabric is necessary, while no established standard for the cut testing of fiber or yarns exists, there are three standards used to evaluate the cut resistance of knitted or woven fabrics used in protective clothing: BS EN 388, ASTMF1790, ISO13997. Now, there are simple models on cut resistance of fabric, consisting of forces in the cutting process and contact area. There are still a lot of work to continue to get a thorough understanding of mechanism of fabric’s cut resistance.

Numerical Analysis of Macro-Scale Mechanical Behaviors of 3D Orthogonal Woven Composites using a Voxel-Based Finite Element Model

A study is conducted with the aim of developing voxel-based finite element method related to the whole fiber distribution for predicting the macro-mechanical properties of 3D orthogonal woven composites. For the rationality of this model, multi-scale finite element method, which is on the basis of the surface and interior representative volume cells, and digital image correlation tests are carried out. The results show that the proposed voxel-based finite element method is capable of precisely calculating the macro-level properties of 3D orthogonal woven composites, validated by the comparison the mechanical behaviors as well as the full-field strain fields.

Numerical Identification of Meso Length-Effect and Full-Field Edge-Effect of 3D Braided Composites

A study is conducted with the aim of developing two numerical models, meso-scale model and fiber embedded matrix model, for evaluating the length-effect and full-field edge-effect of 3D braided composites. Also, for the validation of fiber embedded matrix model, a series of digital image correlation measurements are conducted along the axial directions. The results show that the predicted mechanical behaviors of the tensile and compressive samples are essentially sensitive to the RVC number. Moreover, the proposed fiber embedded matrix method is capable of accurately predicting the cut-edge effect on the full-field mechanical behaviors of 3D braided composites when subjected to the axial tensile and compressive loading, validated by the comparison of the full-field displacement and strain fields.

Bias tensile strength behaviors of woven fabric: theoretical and experimental

Abstract This paper mainly focuses on the uniaxial bias extension behaviors of quartz plain weave fabrics. A series of bias extension tests are carried out on quartz plain weave fabrics with different widths to evaluate the strength behaviors. A portable microscope is adopted to capture and record informative resources on the sample surface. The tensile tenacity, load–displacement curves, width change history as well as Poisson’s ratio history of different sample widths are compared and analyzed. Also, a theoretical model is proposed to predict the critical width which is the maximum width without yarn failure in bias extension test. Theoretical prediction shows reasonable agreement with experiments. Tensile tests operated on three directions (warp, weft, and bias) reveal the significant mechanical difference is primarily caused by different failure mechanisms.

Finite Element Analysis of Warp-Reinforced 2.5D Woven Composites Based on a Meso-Scale Voxel Model under Compression Loading

A study is conducted with the aim of developing meso-scale voxel-based model for evaluating the compressive behaviors of warp-reinforced 2.5D woven composites. The real microstructure of warp-reinforced 2.5D woven composites is established. For the validation of this model, a series of axial (warp direction) and transverse (weft direction) compressive tests are conducted. The results show that under axial and transverse compressive loading, the calculated max stress and the final damage morphology agree well with the experimental results. Moreover, it is found that the axial compressive strength is mainly dependent on the high-crimp blinder warp, while the transverse compressive strength is significantly influenced by the warp/weft interlaced regions. It is expected that such a numerical investigation will provide useful information for understanding the strength and failure characteristic of 2.5D woven composites.