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This work deals with a computational analysis and quantification of the influence of processing (primarily crack-like) defects of various amount on the (tensile) strength of open cell ceramic foam structures. This information is essential e.g. for application of these materials in the mechanically loaded application, where a design with certain reliability to operating conditions is required. The analysed ceramic foam structures are composed of both regular and irregular cells and crack-like defects (pre-cracked struts) are simulated inside them. The foam structure is modelled using a 3D FE beam element based model created by utilization of the Voronoi tessellation technique. The tensile strength upon presence of various amount of pre-cracked struts is analysed based upon an iterative FE simulation on whose base the critical failure force leading to specimen fracture is determined. The performed parametric study relates the tensile strength of the foam structure to the amount of initial defects. With increasing amount of these defects, the foam strength decreases by approximately 30% with every 10% of broken struts. This information can be directly used for a fast estimation of the foam tensile strength if the fraction of broken struts to the intact ones is known (e.g. from a microscopic analysis).

It is widely accepted that bones have the ability to adapt to new biomechanical environment by changing their material properties, geometry and inner architecture. Bones have also an exceptional ability to self-repair, to remove microcracks and to prevent the bone damage caused by the fatigue failure. These abilities are enabled through coupled processes of bone resorption and bone formation, the processes collectively referred to as bone remodeling. Numerous studies have shown that bone remodeling is governed by combination of mechanical stimulus (strains) and its frequency, both sensed by sensor cells (osteocytes). Through mechanotransduction, the stimulus is transmitted to actor cells (osteoclasts, osteoblasts) that actually do the bone resorption or formation. Several theories have been proposed to predict bone remodeling and several finite-element-based algorithms have been introduced. The vast majority of them uses strain energy density as the mechanical stimulus. The purpose of this paper is to investigate and discuss the applicability of also other strain-based representations of the mechanical stimulus in simulations of remodeling of bone with an initial microcrack. The need for developing more reliable models is essential for both clinicians and engineers who are interested, for instance, in prediction of bone performance when various implants are involved.

Using porous bioceramics became recently an alternative approach to increase bone density which is a key factor for successful dental implant application. These novel biomaterials should substitute missing natural trabecular structures in terms of material strength as well as deformation characteristics. However, mechanical behavior of these materials used as bone fillers are still in question. This problem is made more difficult by the fact that bone structure itself exhibits a complex mechanical behavior which is still in question as well and, therefore, appropriate analytical criteria should to be established. The purpose of this paper is to determine typical mechanical behavior of trabecular structure of mandibular cancellous bone using computational simulations which can serve as a basis for establishing such criteria. For this purpose, four bone specimens of various bone density were μCT-scanned and high-level finite element models including detailed trabecular structure were created on their basis to analyze relevant mechanical quantities for various loadings in terms of bone density and various histomorphometric parameters.

The paper deals with a creation of computational model of a high porous ceramic material. This type of material has a large-scale industrial utilization. The computational model was created based on micro-CT data in the ANSYS 14.0 software using Finite Element Method. A creation of a porous ceramic struts model which respect a micro architecture is quite difficult (computer demanding and micro-CT data). The micro-CT slices are converted into a 3D model using image processing (used software STL Model Creator). The local first principle stress was analyzed because, ceramic is the brittle material. Furthermore, the influence of the thick layer around the individual struts was analyzed.

In recent years, particle reinforced composites are widely used due their mechanical properties as construction materials, high-performance engineering materials or protective organic coatings. The paper was mainly focused on the estimating of the interactions of the micro-crack and the particles in the particulate polymer composites. A non-linear material behavior of the matrix was obtained from the experiment and it was used to investigation by means of the finite element method - using ANSYS software. A two-dimensional numerical model was developed and a micro-crack propagation direction was calculated based on the assumption of the linear elastic fracture mechanics. The results indicated that the presence of the interphase between particle and matrix can improve the fracture toughness of the polymer particle composites through debonding process. The paper can contribute to a better understanding of the behavior and failure of the composites with the polymer matrix reinforced by the rigid particles.

The domain of the generalized stress intensity factors dominance ahead of the notch tip can be rather small with respect to the length of the perturbing cracks initiated from the tip of the notch. Thus the non-singular terms of the stress asymptotic expansion at the notch tip would play an important role in the notch tip stability. Following the procedures dealing with complex potential theory and path-independent two-state integrals developed for the singular stress analysis of the stress concentrators one can evaluate their magnitude and include them to the energy release rate of the preexisting crack initiated from the notch tip applying the matched asymptotic procedure. The presented analysis should lead to better understanding of the notch stability process and precising of the notch stability criteria.

This paper is focused on computational modeling of an interaction of dental implant with mandible bone. It describes creation of computational model including model of geometry, materials, loads and constraints. There is a comparative stress-strain analysis of the levels of cancellous bone model. Computations are performed with the use of finite element method. Results show differences between the model which includes trabecular architecture of cancellous bone tissue and the model with non-trabecular cancellous bone tissue. For better description of the processes in bone tissue and at the interface between bone tissue and implant, it is necessary to create the computational model on the highest possible level, i.e. with the trabecular bone tissue.

This article deals with presentation of data processing obtained from imaging CT (computer tomography) and micro CT devices. These methods enable to perform bone tissue density analysis by non-invasive way. The image processing methods, by which it is possible to determine mechanical properties of bone tissue, are described in this paper. Further, a creation of a computational model with different bone density of cancellous tissue is described and afterwards the stress strain analysis is performed. The mandible segments with different bone density were used as samples. Results show significantly higher stresses are reached in a cancellous bone tissue with worse bone quality.

This article is focused on computational modeling of an interaction of malleable lumbar spine fixation device with ambient bone tissue focusing on solving problems of clinical practise. It describes creation of computational model including model of geometry, materials, loads and constraints. There is a comparative stress strain analysis of spinal segment after fixation device application with its physiological state. Computations are performed with use of FEM method. To simulate natural way of loading we used the compression of motional spinal segment. Results show the difference between the system including intervertebral disc in between vertebras and the system with applied lumbar spinal fixation device.

The presented paper describes the creation of a computational model of highly porous materials, and a stress-strain analysis is performed. The computational model is created using micro-CT by the finite element method in the ANSYS 12.0 software. The micro-CT slices are converted into a 3D model using image processing. The local equivalent stress (HMH criterion) and struts deformation are analyzed. Commercially available ceramic foam, 85%Al2O3-14%SiO2- 1%MgO, was used in the experiment part of the paper.