Characterisation of Aluminium Matrix Syntactic Foams under Dynamic Loading

Altenaiji, M, Guan, Zhongwei ORCID: 0000-0002-6967-3508, Wesley, Cantwell, Zhao, YY and Schleyer, GK
(2013) Characterisation of Aluminium Matrix Syntactic Foams under Dynamic Loading. Doctor of Philosophy thesis, University of Liverpool.

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In this study, aluminium matrix syntactic foams reinforced with several types of ceramic micro-sphere were produced by pressure infiltration. The mechanical properties of a range of aluminium matrix syntactic foams were investigated in order to optimise the composition and structure to find the best configuration in terms of high energy absorption capability, and to validate the finite element predictions against the corresponding experimental results. Initially, the compressive behaviour of six different types of aluminium matrix syntactic foam was evaluated. It was shown that the size of the ceramic micro-spheres, the grade of the aluminium matrix and the volume fraction of the aluminium matrix all have a significant influence on the compressive strength and energy absorption capability of the material. Then, the three-point bending and shear fracture properties of aluminium syntactic foams were evaluated. These tests indicated that density plays an important role in determining the stiffness, specific energy absorption and ultimate flexural strain. Here, it was found that the specific energy absorption related to shear was lower than that corresponding to flexure. Following this, the behaviour of the syntactic foams under low velocity impact was characterised and the underlying failure mechanisms were identified to evaluate their effective mechanical performance. It was found that the aluminium syntactic foams subjected to drop-weight impact have 20–30% higher plateau values than samples subjected to the equivalent level of quasi-static compression. Subsequently, the Split Hopkinson Pressure Bar technique was used to investigate the behaviour of the material at high strain-rates, which highlighted the material sensitivity of aluminium syntactic foams under high strain-rate loading. Following this, terminal ballistic tests were conducted to determine the perforation resistance of the aluminium syntactic foams. The results showed that the syntactic foams have the ability to prevent the perforation of projectile velocities up to 120 m/s. Finally, blast tests were performed to investigate the influence of the charge mass and sample thickness on the dynamic response of the syntactic foams. The results showed that syntactic foams with a thickness of 14 mm have the capability to sustain a blast load of 4.82 Ns. Finite element models were developed to simulate the structural behaviour of aluminium syntactic foams subjected to various quasi-static and dynamic loads. Here, an elasto-plastic model with both ductile and shear failure criteria was employed to predict the material performance. The rate-dependent response of the foam was considered by a stress-ratio based model to take strain-rate effects into account. The numerical simulations were compared with their corresponding experimental results with reasonably good correlation. In general, the essential features of the aluminium syntactic foams tested under different loading regimes were captured by the FE models, including load-displacement traces, deformation and failure modes.

Item Type: Thesis (Doctor of Philosophy)
Additional Information: Date: 2014-03 (completed)
Uncontrolled Keywords: Metal Matrix Syntactic Foam, Drop Weight Impact, Split Hopkinson Pressure Bar, Finite Element, Energy Absorption
Subjects: ?? TA ??
Depositing User: Symplectic Admin
Date Deposited: 07 Aug 2014 10:58
Last Modified: 16 Dec 2022 04:42
DOI: 10.17638/00018857
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