Micromechanical FE Analysis of SiCf/SiC Composite with BN Interface

Silicon - The current study presents a micromechanical Finite Element Analysis (FEA) methodology to predict the room temperature transverse tensile failure behavior of a SiCf/SiC composite (Silicon...     

Local strain in a 5-harness satin weave composite under static tension: Part II - Meso-FE analysis

This paper presents the local strain analysis in a thermo-plastic 5-harness satin weave composite under uni-axial static tensile load using meso-FE simulations. In order to predict the local strain profiles as observed in the experiments (Part I) at various locations of the composite, different unit cell stacking models with appropriate boundary conditions are used for the FE analysis. Apart from the calculation of local strain values at different locations (inside/traction free surface) of the composite laminate, the aim of the numerical simulations is to understand the ‘shadowing’ effects of the internal ply shifting on the surface strain behavior of a 5-harness satin weave composite. Comparison of the experimental local strain values (Part I) at various locations of the satin weave composite reveals that the effects of local yarn constraints are negligible on the local longitudinal strain behavior of the composite.However, local stress-strain profiles obtained from unit cell meso-FE simulations indicate that the longitudinal strain and the transverse stress distribution in the weft yarn at the yarn crimp location is sensitive to the unit cell stacking as well as to the applied boundary conditions to the unit cell.     

Local damage in a 5-harness satin weave composite under static tension: Part II – Meso-FE modelling

This study forms the second part of a paper on the local damage analysis in a thermo-plastic 5-harness satin weave composite under uni-axial static tensile load. The experimental observations of Part I are confronted with the meso-FE simulations. Part II describes the following steps regarding the unit cell meso-FE modelling starting from: (1) construction of the unit cell geometrical model; (2) estimation of the homogenized elastic constants of the unit cell using different boundary conditions; (3) evaluation of the local stress and damage behavior of the unit cell using meso-FE simulations. The aim of the numerical analysis is to investigate the dependency of local ply stress and damage profiles on the adjacent layers of the laminate.     

Local damage in a 5-harness satin weave composite under static tension: Part I – Experimental analysis

This paper presents an experimental damage analysis of a 5-harness satin weave carbon–PPS (polyphenylene sulphide) composite under uni-axial static tensile load. In order to understand the local damage behaviour, tensile tests were performed and accompanied by acoustic emission (AE) and microscopic analysis of the composite specimen. These tests enable us to detect the damage initiation stress as well as the damage initiation location in the composite. Microscopic observation of the tested composite laminates allowed the characterization of the sequence of intra-yarn transverse damage (perpendicular to the load direction) occurrence at different locations in the laminate, starting from crack initiation to the final failure of the composite.     

Local strain in a 5-harness satin weave composite under static tension: Part I - Experimental analysis

This paper presents an experimental method for determining the local strain distribution in the plies of a thermoplastic 5-harness satin weave composite under uni-axial static tensile load. In contrast to uni-directional composites, the yarn interlacing pattern in textile composites causes heterogeneous strain fields with large strain gradients around the yarn crimp regions. In addition, depending on the local constraints that are imposed by the surrounding plies, the deformation behavior of the laminate inner layers may vary from that of the surface layers, which are relatively more free to deform, compared to the inner layers. In order to validate the above hypothesis, the local strains on the composite surface were measured using digital image correlation technique (LIMESS). Internal strains in the composite laminate were measured using embedded fibre optic sensors (FOS).Based on the DIC results, the strain profiles at various locations on the composite surface were estimated. Using the FOS results, the maximum and minimum strain values in the laminate inner layers were evaluated. Comparison of the local strain values at different laminate positions provides an estimate of the influence of the adjacent layers on the local longitudinal strain behavior of a satin weave composite. Part II of this paper elucidates the local strain variation computed using the meso-FE simulations. In addition to the comparison of numerical and experimental strain profiles, Part II presents the maximum and minimum strain envelopes for the carbon-PolyPhenelyne Sulphide (PPS) thermoplastic 5-harness satin weave composite.