Failure Processes in Elastic Fiber Bundles

The fiber bundle model describes a collection of elastic fibers under load. the fibers fail successively and for each failure, the load distribution among the surviving fibers change. Even though very simple, the model captures the essentials of failure processes in a large number of materials and settings. We present here a review of fiber bundle model with different load redistribution mechanism from the point of view of statistics and statistical physics rather than materials science, with a focus on concepts such as criticality, universality and fluctuations. We discuss the fiber bundle model as a tool for understanding phenomena such as creep, and fatigue, how it is used to describe the behavior of fiber reinforced composites as well as modelling e.g. network failure, traffic jams and earthquake dynamics.Comment: This article has been Editorially approved for publication in Reviews of Modern Physic

Wpływ mikrostruktury na zniszczenie kompozytu - analiza numeryczna

In this paper, microstructural effects on the damage resistance of composite materials are studied numerically using methods of computational mesomechanics of materials and virtual experiments. Several methods and programs for automatic generation of 3D microstructural models of composites based on the geometrical description of microstructures as well as on the voxel array data have been developed and tested. 3D FE (Finite Element) simulations of the deformation and damage evolution in particle reinforced composites are carried out for different microstructures of the composites. Some recommendations for the improvement of the damage resistance of lightweight metal matrix composites with ceramic reinforcements are obtained.W artykule przedstawiono analizę wpływu mikrostruktury materiałów kompozytowych na ich odporność na zniszczenie, przeprowadzając badania symulacyjne oparte na modelach obliczeniowych stosowanych w mezo-mechanice oraz na eksperymentach numerycznych. Opisano zaproponowane i przetestowane programy do automatycznego generowania trójwymiarowych modeli mikrostruktur kompozytowych bazujące na opisie geometrycznym z zastosowaniem techniki wokseli (3-wymiarowych odpowiedników pikseli). Przeprowadzono symulacje deformacji i ewolucji zniszczenia elementów skończonych reprezentujących kompozyty z wtrąceniami punktowymi o różnej mikrostrukturze. Sformułowano pewne wytyczne dla poprawy odporności na zniszczenia lekkich kompozytów zbudowanych z metalicznego lepiszcza wzmacnianego ceramiką

Three-Dimensional Numerical Testing of Microstructures of Particle Reinforced Composites

Three-dimensional finite element (FE) simulations of the deformation and damage evolution of SiC particle reinforced Al composites are carried out for di#erent microstructures of the composites. A program for the automatic generation and the design of FE meshes for di#erent 3D microstructures of composites is developed. Numerical testing of composites with random, regular, clustered and gradient arrangements of spherical particles is carried out. The fraction of failed particles and the tensile stress--strain curves were determined numerically for each of the microstructures. It was found that the strain hardening coe#cient increases with varying the particle arrangement in the following order: gradient random clustered regular microstructure. The variations of the particle sizes causes strong decrease in the strain hardening rate of the composite, and leads to the quicker and earlier damage growth in the composites

Computational Modeling Of Crack Propagation In Real Microstructures Of Steels And Virtual Testing Of Artificially Designed Materials

A computational approach to the optimization of service properties of two-phase materials (in this case, fracture resistance of tool steels) by varying their microstructure is developed. The main points of the optimization of steels are as follows: (1) numerical simulation of crack initiation and growth in real microstructures of materials with the use of the multiphase finite elements (MPFE) and the element elimination technique (EET), (2) simulation of crack growth in idealized quasi-real microstructures (net-like, band-like and random distributions of the primary carbides in the steels) and (3) the comparison of fracture resistances of different microstructures and (4) the development of recommendations to the improvement of the fracture toughness of steels. The fracture toughness and the fractal dimension of a fracture surface are determined numerically for each microstructure. It is shown that the fracture resistance of the steels with finer microstructures is sufficiently higher than that for coarse microstructures. Three main mechanisms of increasing fracture toughness of steels by varying the carbide distribution are identified: crack deflection by carbide layers perpendicular to the initial crack direction, crack growth along the network of carbides and crack branching caused by damage initiation at random sites