Free vibration analysis of patched cracked composite laminates using a multilayer hybrid-stress finite element method

[[abstract]]An assumed hybrid-stress finite element model incorporating two types of modified composite multilayer elements (MLTUP and MLTPH) is developed to investigate the free vibration of doubly and singly patched cracked laminates. Three-dimensional stresses of the laminated panel, patch and adhesive are accounted for. A composite patch material which has an efficient patching characteristic is employed. The effect of the patch parameters (length, thickness. width and position) on the fundamental natural frequency is also investigated. For a simply supported condition, the variation of the fundamental natural frequency after patching is negligible. However, the maximum variation of the fundamental natural frequency after patching for the problems solved under the cantilever edge condition is ca 10%. When the patch parameters are selected appropriately, the fundamental natural frequency after patching may become the same as that of the original uncracked laminate. This illustrates that the composite patch studied is a good choice for patching the cracked laminate tackled. The variations of the fundamental natural frequency for various crack lengths after patching are additionally presented. The technique developed can further be employed to treat a more realistic patching problem owing to that based on a three-dimensional viewpoint.[[fileno]]2020224010026[[department]]動機