Analysis of Wave Propagation in Monolithic and Functionally Graded Ti-TiB Plates Subject to Impact Loading

Autor: Anthony N. Palazotto, Hugh E. Gardenier, Reid A. Larson
Rok vydání: 2008
Předmět:
Zdroj: 49th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference 16th AIAA/ASME/AHS Adaptive Structures Conference 10t.
DOI: 10.2514/6.2008-1744
Popis: Functionally graded materials (FGMs) have gained significant interest within the research community in recent years. FGMs are advanced composites where local material properties are tailored to suit application requirements by altering the volume fraction ratios of two or more constituents. In this paper, the behavior of metal-ceramic FGM plates under low-velocity, medium-energy impact loading is considered using experimental and computational techniques. First, the results from a series of impact tests conducted on monolithic and functionally graded plates composed of titanium (Ti) and titanium boride (TiB) are presented. The impact tests were performed using a vertical drop test apparatus in which highly controlled impact events can be delivered with energy levels up to 442 Joules. The plates were impacted with various velocities and energy levels directly at the center of the top surface of each plate. The opposing bottom surface of each plate was instrumented with strain gages wired into a high-speed data acquisition system so that strain histories could be collected throughout the duration of each impact event. Next, the details associated with a finite element model constructed to simulate the experiments are discussed. Two distinct material models were used in the finite element analyses to study the monolithic and graded plates. The first model used analytical expressions based on local volume fractions of the constituents to generate homogenized material properties for the mixtures of Ti and TiB. The second model randomly distributed cells containing Ti-elements and TiBelements constrained to satisfy local volume fraction ratios in the monolithic and graded specimens. The strain histories from the experiments were compared to the analogous solutions from the finite element analyses to validate the computational models used in the study. Finally, an analysis of the effects of the wave propagation within the graded plates is provided, especially concerning the transmission and reflection characteristics of the incident stress waves generated from the impact events.
Databáze: OpenAIRE
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