Investigating Failure Behaviors of Debonded Composite Sandwich Structures - Experiments and Simulation
|Keywords:||複合材料三明治結構;脫層缺陷;破壞行為;非線性分析;composite sandwich structure;debonded defect;fracture behavior;nonlinear analysis|
With the worldwide tendency of energy conservation, composite sandwich structures with the characteristics of light weight and superlative bending rigidity and strength have been extensively employed in industries, i.e., aerospace, automobile, wind turbine blade. However, because of the manufacturing negligence or low velocity impact, the face/core debonded defects are easily generated within the composite sandwich structure resulting in the substantial reduction of mechanical performance. Thus, understanding the fracture behavior and strength of sandwich structure with debonded defect is an essential task for the industrial application with safety. When the debonded length is greater than the critical length, the failure mode of sandwich structures under compressive loading basically is the local buckling within the debonded region. The effect of composites lay-up sequence, face sheet thickness and core properties on the critical length will be taken into accounted in this study. The debonded composite sandwich specimens were fabricated with graphite/epoxy composite laminates as face sheet and polymethacrylimide form as core. During the fabrication, a release film was artificially embedded between the face sheet and core for the creation of debonded defect. Preliminary experimental observations indicated that the failure is dominated by face sheet local buckling followed by the core failure near the interfacial region. In addition to experimental observation, the finite element analysis was also conducted to characterize the fracture behaviors of the sandwich structures. The buckling mode of the debonded sandwich structure was obtained first from the linear buckling analysis. Subsequently, the buckling mode was regarded as the initial perturbation in the nonlinear analysis, based which the critical buckling load was calculated. Furthermore, in accordance with the maximum tensile stress criterion, the compressive strength of debonded sandwich strength in terms of core failure was predicted accordingly. The simulation results and experimental data will be compared and discussed with each other.
|Gov't Doc #:||NSC101-2221-E009-029-MY2|
|Appears in Collections:||Research Plans|