A micromechanical model of carbon fiber-reinforced plastic and steel hybrid laminate composites

The fracture strain of carbon fiber-reinforced plastics (CFRPs) within CFRP/steel hybrid laminate composites is reportedly higher than that of CFRPs due to transverse compressive stress induced by the steel lamina. A micromechanical model was developed to explain this phenomenon and also to predict the mechanical behavior of CFRP/steel hybrid laminate composites. First, the shear lag theory was extended to calculate stress distributions on fibers and matrix material in a CFRP under multiaxial stress condition, considering three deformation states of matrix (elastic and plastic deformation and fracture) and the transverse compressive stress. Then, the deformation behavior of CFRP was predicted using average stress in the ineffective region and the Weibull distribution of carbon fibers. Finally, the mechanical properties of CFRP/steel hybrid laminate composites were predicted by considering the thermal residual stress generated during the manufacturing process. The micromechanical model revealed that increased transverse compressive stress decreases the ineffective lengths of partially broken fibers in the CFRP and results in increased fracture strain of the CFRP, demonstrating the validity of the current micromechanical model.

Analysis of the Bi-Stable Hybrid Laminate under Thermal Load

Adaptive structures have the ability to modify their shapes in different operational conditions. Multi-stable structures are one of the methods of making adaptive structures. In the bi-stable square laminates, due to geometric symmetry and equality of strain energy between stable states, it is possible to continue actuating between stable states, specially when using dynamic or thermal load. The bi-stability of the hybrid square laminated structure with the stacking sequence of [0/90/Al] is asymmetric. This leads to inequality of strain energy in stable states and therefore, development of an effective method to control and avoid automatic actuating. In this paper, the deformation and strain energy of the bi-stable hybrid square laminated structure is investigated. To show the effect of elastic boundary condition, a similar section with the stacking sequence of [0/0/Al] is connected to the mentioned hybrid laminate. The effects of the temperature, the presence of an aluminum layer and its thickness on the potential multiple shapes are also studied. To check the accuracy, the bi-stability behavior is investigated using finite element analysis and the results are compared with the experimental data.

The Effect of Stacking Sequence and Ply Orientation on the Mechanical Properties of Pineapple Leaf Fibre (PALF)/Carbon Hybrid Laminate Composites

In this paper, the effects of stacking sequence and ply orientation on the mechanical properties of pineapple leaf fibre (PALF)/carbon hybrid laminate composites were investigated. The hybrid laminates were fabricated using a vacuum infusion technique in which the stacking sequences and ply orientations were varied, which were divided into the categories of cross-ply symmetric, angle-ply symmetric, and symmetric quasi-isotropic. The results of tensile and flexural tests showed that the laminate with interior carbon plies and ply orientation [0°, 90°] exhibited the highest tensile strength (187.67 MPa) and modulus (5.23 GPa). However, the highest flexural strength (289.46 MPa) and modulus (4.82 GPa) were recorded for the laminate with exterior carbon plies and the same ply orientation. The fracture behaviour of the laminates was determined by using scanning electron microscopy, and the results showed that failure usually initiated at the weakest PALF layer. The failure modes included fibre pull-out, fibre breaking, matrix crack, debonding, and delamination.