Characterization and Numerical Modelling of Through-Thickness Metallic-Pin-Reinforced Fibre/Thermoplastic Composites under Bending Loading

Through-Thickness Reinforcement (TTR) technologies are well suited to improving the mechanical properties in the out-of-plane direction of fibre-reinforced composites. However, besides the enhancement of delamination resistance and thus the prevention of overall catastrophic failure, the presence of additional reinforcement elements in the composite structure affects also the mechanical properties in in-plane direction. In this work, the flexural behaviour of a glass-polypropylene (GF/PP) hybrid yarn-based composite with TTR in form of metallic pins has been investigated experimentally and numerically. The insertion of the metallic pins is realized via thermoactivated pinning technology (TAP). In four-point-bending tests, it is shown that the flexural stiffness and strength decreases with an increase of the overall pin density. Hereby, it is observed that the pins act as crack initiators. For numerical modelling on specimen level, a continuum damage mechanic (CDM) model is used to predict the nonlinear deformation response of the composite, as well as fibre fracture and matrix cracking. A debonding and slipping phenomena of the pin in the composite is modelled by a cohesive zone modelling approach for the interface between pin and composite.

Numerical simulation of single-lap adhesive joint of composite laminates

A universal method is established to research the various possible damage modes of adhesive bond of laminated composites with or without z-pin reinforcements under tensile loads through numerical simulation. A Continuum Damage Mechanic model based on Hashin damage criterion as a user-defined subroutine is developed to simulate the damage of laminates and Z-pins. The Cohesive Zone Model is used to simulate the damage of adhesive damage, interlayer delamination, and Z-pin slipping-out phenomenon. The numerical simulation method is validated for simulating the various damage modes of the usual composite joints through comparing the simulated results and experiments. The research shows that different ply sequences induce different damage modes and ultimate failure loads of composite joints. The ultimate failure load of joint under tension is not affected obviously whether the joints are reinforced with or without z-pins. The reason is that the damage initiation usually locates at the two sides of adhesive zone and z-pins do not react on the reinforcement under tensile load of joint.

Prediction of Rupture in Gas Forming Process Using Continuum Damage Mechanic

The Continuum Damage Mechanics is a branch of applied mechanics that used to predict the initiation of cracks in metal forming process. In this article, damage definition and ductile damage model are explained, and also ductile damage model is applied to predict initiation of fracture in gas metal forming process with ABAQUS/EXPLICIT simulation. In this method instead of punch, the force is applied by air pressure. In this study, first the ductile damage criterion and its relations are taken into account and, subsequently, the process of gas-aid formation process is put into consideration and ductile damage model for prediction of rupture area is simulated using ABAQUS simulation software. Eventually, the process of formation via gas on the aluminum with total thickness of 0.24 [mm] was experimentally investigated and the results acquired from experiment were compared with relating simulations. The effect of various parameters such as radius of edge matrix, gas pressure and blank temperature has been evaluated. Simulation was compared with experimental results and good agreement was observed.