Quasi-static impact response

Material properties. In addition to the common knowledge that the materials must be stronger, tougher, and lighter [79], it is envisioned that the materials must be less stiff during impact so that the impact duration can be extended and the elastic wave will have sufficient time to reach and be reflected by the boundary many times for a quasi-static response, as discussed by Olsson [76]. However, this requirement is contradictory to the structural requirement that is, the material must be stiff to provide structural capacity. 

An important measure of injury to an occupant in an aircraft accident is the amount of load transferred to the occupant lumbar spine [24]. The two dimensional occupant model utilizes a typical load-deflection formula of an intact lumbar spine vertebral column to predict the axial load and moments acting on the lumbar. This results in an incorrect representation of the dynamic responses produced by the spinal column during an impact. In order to predict the internal forces and moments in the spine, a finite element model has been incorporated into the occupant model. To overcome the problems of instability and inefficiency, a quasi-static methodology has been developed, which combines the finite element methods with rigid multibody dynamics principles. A description of this methodology is provided next. 

Similar to quasi-static indentation tests, the effect of 1 wt% NC and 1 wt% GB fillers on the impact response of GFRP was initially investigated. Figure 19.13 shows representative force—time curves for each material configuration. As seen in Figure 19.13,... 

The objective of the current work was to compare FOD behavior between the SiC/SiC and the oxide/oxide CMCs in terms of impact morphologies and strength degradation, based on the previous work [1-2], In addition, the response to static indentation of the two composites with respect to deformation was also characterized using the same steel balls that were employed in the previous FOD testing. The static indentation results were then used in order to make an attempt of quasi-static prediction of impact force as a function of impact velocity involved in the FOD testing. 

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