Papers by Keyword: Impact Damage (ID)

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Authors: C. Wang, H. Zhang, Guang Yu Shi
Abstract: This paper presents the finite element damage simulation of laminated plates induced by low-velocity transverse impact. The solid elements are used to model the laminae, and the solid-shell interface elements are employed to characterize the behavior of the interfacial layers of the laminated plates. The material properties of the adhesive layers are used in the solid-shell interfacial elements for the damage prediction. The simulated damage propagation agrees well with the experimental results. Therefore, the numerical results show that the solid-shell interface element is a good computational model for the interfacial layer modeling in the damage simulation.
Authors: Young Shin Lee, Hyun Soo Kim, Young Jin Choi, Jae Hoon Kim
Abstract: The laminated composite structures applied to the wing and the speed brake of an aircraft or the turbine blade of a compressor. These structures may be impacted by birds and hails during operation. They may also be impacted by drop of a tool during manufacture or repair. Unlike high velocity impact damage, which can be easily found by the naked eye, the damage due to low velocity impact may be difficult to detect. Damage which is not detected may cause failure of a structure and result in damage propagation. Growth of damage means reduction of stiffness on the structure. So, exact prediction of damage caused by a low velocity impact is very important in order to guard against sudden failure of the structure. In this study, modified delamination failure criterion has suggested in order to predict the failure behavior of a composite plate subjected to low-velocity impact. The criterion includes the assumption which is matrix cracking mode causes delamination failure. Predicted damage using supposed delamination criterion is similar to experiment results.
Authors: M.T.H. Sultan, Alma Hodzic, W.J. Staszewski, Keith Worden
Abstract: The ultimate objective of the current programme of work is to detect and quantify low-velocity impact damage in structures made from composite materials. There are many situations in the use of composites where an impact does not result in perforation of the material but causes damage that may not be visible, yet still causes a substantial reduction in structural properties. Impacts that do not cause perforation are usually termed low-velocity. When a composite structure undergoes such impacts, it is important to know the type and level of damage and assess the residual strength. In this study, following a systematic series of experiments on the induction of impact damage in composite specimens, Scanning Electron Microscopy (SEM) was used to inspect the topographies of the specimens at high magnification. Matrix cracking, fibre fracture, fibre pullout and delamination were the types of damage observed in the composite laminates after the low-velocity impacts. The study also conducted a (very) preliminary correlation between the damage modes and the impact energy.
Authors: Mark J. Eaton, Karen M. Holford, C.A. Featherston, Rhys Pullin
Abstract: The presence of impact damage in a carbon fibre composite can reduce its capacity to support an in-plane load, which can lead to an unexpected or premature failure. This paper reports on an investigation into two slender carbon/fibre epoxy panels, one un-damaged and one with an artificial delamination introduced using an embedded section of PTFE. The reported tests form part of a larger series of investigations using differing sizes of artificial delamination and real impact damage. An investigation of wave velocity propagation at varying angles to the composite lay up was completed to assist in source location. The specimens were loaded under, uniaxial in-plane loading and monitored using four resonant acoustic emission sensors. A full field optical measurement system was used to measure the global displacement of the specimens. Analysis of AE waveforms and AE hit rate were used to assess the buckling of the panel. The results compared favourably with the optical measurement results.
Authors: Han Ki Yoon, Jin Kyung Lee, Yi Hyun Park, Jung Ho Lee, Jea Heon Lee
Authors: Zhe Sun, Fei Xu, Wei Xie, Bo Wang
Abstract: Composite stiffened panels are widely used in the modern aircraft structure with the advantages of light weight, structural efficiency and good crack performance. But the stiffened panels have poor performance at thickness direction, especially for low-velocity impact. First of all, compressive tests were investigated and analyzed for two types of composite stiffened panels, which are integrated specimens and post-impact specimens. And the effect of low-velocity impact to the supporting capacity of composite stiffened panels was researched. Secondly,the finite element model was established to simulate the CAI (Compression After Impact)strength with the equivalent hole method. It is found that the analyze results match the experimental results well. According to the experimental results, structural damage and the maximum load caused by impact energy are scattering. Then the imperfect factors were introduced to reflect the initial imperfection, namely the initial deflection at thickness direction. The effect of different imperfect factors to the maximum load was discussed.
Authors: Man Yi Hou, Hui Lin Fan, Wu Lin Zhu
Abstract: In order to research the aircraft impact damage, one symbolic fitting method for analyzing and forecasting the damage data is proposed based on genetic programming (GP). The method can be used to forecast the impact damage by recognizing the rule in some groups of actual data including impact parameters and damage hole size. The principle of GP symbolic fitting method is briefly introduced. The fitting model is created with some sample data respectively for training and testing from Sorenson experiential equation. The computation with Matlab program indicates the model has a good performance to fit and forecast the damage data with avoiding the noise. The application of GP symbolic fitting method can help to decrease the times of fire experiments. Since the method can recognize the complicated nonlinear relationship between the impact parameters and damage data, it is more applicable than theoretical analysis and experiential equation to forecast the aircraft impact damage.
Authors: Da Peng Chen, Nai Ming Wu, Zheng Zhang, Yue Li, Xiao Xia Li, Cun Lin Zhang
Abstract: Carbon fiber reinforced polymer (CFRP) composites have been used extensively because of their excellent performance, but they are susceptible to the impact damages, such as the impact of birds, runway stones and tools off can cause the failure of CFRP composites. Therefore, nondestructive testing of CFRP composites is necessary to promote the failure control and prevention. Ultrasonic burst phase thermography (UBP) developed a few years ago is a defect-selective and fast imaging tool for damage detection. This paper describes the principle of UBP, gives some UBP testing results of impact damages in five CFRP laminated boards. The shape and position of the damages are shown in the phase images visualized and the relationship between the damage areas and impact energy is discussed. The flash pulse thermography (PT) results and ultrasonic C-scan results are also shown as comparison. It is concluded that all of the three NDT methods have their own characteristics and the comparison verifies the feasibility of CFRP impact damage detection using ultrasonic burst phase thermography.
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