Bending Strength and Fracture Behaviour of Metal-Ceramic Interpenetrating Phase Composites Manufactured by Using Semi-Solid Forming Technology

Interpenetrating Phase Composites (IPC) belong to a special category of composite materials, offering great potential in terms of material properties due to the continuous volume structure of both composite components. While manufacturing of metal-ceramic IPC via existing casting and infiltration processes leads to structural deficits, semi-solid forming represents a promising technology for producing IPC components without such defects. Thereby, a solid open pore body made of ceramic is infiltrated with a metallic material in the semi-solid state. Good structural characteristics of the microstructure as the integrity of the open-pore bodies after infiltration and an almost none residual porosity within the composites have already been proven for this manufacturing route within a certain process window. On this basis, the following paper focuses on the mechanical properties such as bending strength of metal-ceramic IPC produced by using semi-solid forming technology. Thereby, the impact of the significant process parameters on these properties is analysed within a suitable process window. Furthermore, a fractographic analysis is carried out by observing and interpreting the fracture behaviour during these tests and the fracture surface thereafter.

Analysis on fracture behaviour of stitched foam sandwich composites using interlaminar tension test

Sandwich composites are susceptible to interfacial delamination, owing to the mismatches in the material properties between the face sheets and core. Previous studies have shown that stitching can improve the performance of sandwich composites. In this study, an analysis approach was developed to investigate the fracture behaviour of stitched foam sandwich composites. The stitched foam sandwich composites were manufactured by a vacuum-assisted resin transfer moulding process. Interlaminar tension tests revealed the effects of the linear thread density on the failure mechanisms of the stitched foam sandwich composites. Asymmetric double cantilever beam tests were performed to investigate the influences of the stitch thread reinforcement on the fracture behaviour. An analytical approach combining extended finite element method and nonlinear spring elements was proposed to predict the failure behaviour of the stitched sandwich composites. Experiment and simulation approaches were employed to investigate the influences of the stitch parameters (stitch pitch and linear thread density) on the ultimate load and energy absorption. The results show that stitched method can significantly enhance the mechanical properties of sandwich composites. The energy absorption and ultimate load values of the specimens tend to increase with an increase in the linear thread density or a decrease in the stitch pitch.

A Novel Implementation of the LDEM in the Ansys LS-DYNA Finite Element Code

In this paper, a novel implementation of the Lattice Discrete Element Method (LDEM) is proposed: in particular, the LDEM is implemented in the Ansys LS-DYNA finite element code. Such an implementation is employed to evaluate the fracture behaviour of sandwich panels under bending. First, the novel hybrid model proposed is validated by simulating some three-point bending experimental tests carried out at the University of Parma, and then it is used to model the fracture behaviour of sandwich panels under four-point bending. Failure mechanisms, damage locations, and load-deflection curves are numerically determined by employing such a novel model, and the results show a good agreement with the available experimental findings.

Numerical Simulation of the Fracture Behaviour of High-Performance Fibre Reinforced Concrete by Using a Cohesive-Crack-Based Inverse Analysis

Fibre reinforced concrete (FRC) has become an alternative for structural applications due its outstanding mechanical properties. The appearance of new types of fibres and the fibre cocktails that can be configured mixing them has created FRC that clearly exceed the minimum mechanical properties required in the standards. Consequently, in order to take full advantage of the contribution of the fibres in construction projects, it is of great interest to have constitutive models that simulate the behaviour of the materials. This study aimed to simulate the fracture behaviour of five types of FRC, three with steel hooked fibres, one with a combination of two types of steel fibres and one with a combination of polyolefin fibres and two types of steel fibres, by means of an inverse analysis based on the cohesive crack approach. The results of the numerical simulations defined the softening functions of each FRC formulation and have pointed out the synergies that are created through use of fibre cocktails. The information obtained might suppose a remarkable advance for designers using high-performance FRC in structural elements.

Numerical Simulation of Cracking in Asphalt Concrete Through Continuum and Discrete Damage Model

This study describes the development of Continuum and Discrete Damage Models in commercial finite element code Abaqus/Standard. The Concrete Damage Plasticity Model has been simulated, analysed, and compared the result with the experimental data. For verification, the Cohesive Zone Model has been simulated and analysed. Furthermore, the Extended Finite Element Model and concrete damage model are discussed and compared. The continuum damage model tends to simulate the complex fracture behaviour like crack initiation and propagation along with the invariance of the result, while the cohesive zone model can simulate and propagate the crack as well as the good agreement of the result. Further work in the proposed numerical models can better simulate the fracture behaviour of asphalt concrete in near future. Keywords: Model, Concrete, Cohesive Zone, Finite element, Abaqus.