Material characterization and residual stresses simulation during the manufacturing process of epoxy matrix composites

Experimental study on the bending properties and failure mechanism of 3D multi-axial warp knitted composites at room and liquid nitrogen temperatures

“…23,24 Moreover, gradients of in-plane stresses through the thickness can arise, which cause bending when the stresses are released. 25 This also proves that the material has higher bending strength and larger bending deflection than that at room temperature. So, at liquid nitrogen temperature, the local damage for material A is increased significantly and it is the local brittle fracture for 0 fiber bundles under the compression and shear stress that leads to the fracture of composite.…”

Composite materials – modelling, prediction and optimization

“…Temperature and degree of cure are also extremely important in relation to process-induced stresses and strains, infl uencing fi rst of all the state of the material (liquid, gelled solid or vitrifi ed solid) and, as a consequence, its mechanical properties [9]. It is generally accepted that stresses and deformations in composite laminates are related to the interaction between the tool and the part [10], and to gradients in the temperature and degree of cure through the thickness of the composite [11]. Graphical evidence of the connections between the phenomena involved is depicted in Figure 5.1 , well highlighting the multi-physics nature of the problem and models considered.…”

“…at each location in the composite material undergoing processing, all the constituents experience the same temperature), the whole temperature fi eld can be established by solving a unique non-linear equation using lumped (homogenized) material properties [4][5][6][7][8][9][10][11][16][17][18], which can be written as Streamlines of resin fl ow in the tapered region of the die Figure 5.21 [5.46] where T is the temperature; t is the time; ρ c is the density; c p ,c is the specifi c heat capacity; k x ,c , k y ,c and k z ,c are the thermal conductivities of the composite material along the x (pull), y and z directions, respectively; and V r is the resin volume fraction. The source term q in Eq.…”

Experimental and numerical study of distortion in flat, L‐shaped, and U‐shaped carbon fiber–epoxy composite parts

“…Studying changes of mechanical properties in composite materials in order to better understand the residual stresses and resulting distortion in composite parts is important [4,16,17,[25][26][27][28][29][30][31][32][33][34]. Knowledge of the mechanical properties variation in a composite part makes it possible to estimate the residual stresses developed during the curing of the part.…”