A design influence on the mechanical compliance and fracture resistance of railway wheel

A fracture mechanics approach is used to determinate crack behaviour in a railway wheel which is working under different operating conditions with consideration of different types of railway wheel discs. Reliability of the railway wheel is related to a material failure. This paper is focused on failure of the material which is connected with violation consistency of the wheel material. The fracture mechanic approach is applied with consideration of influence of mechanical compliance. The topology optimization is used to define the shape of one disc type. Obtained results show fracture behaviour and the mechanical compliance of used railway wheel discs. From these results, comparison of separated railway wheel discs is obtained

Biomechanical study of bone-dental implant interactions using patient-specific approach and multiscale computational modeling

The research was supported by the Czech Science Foundation: Grant No. 16-08944S.Dental implants are modern solutions for the cases of lost tooth replacements. Although the application of dental implants is relatively efficient solution, complications and failure of dental implant might occur [3]. This contribution is focused on the mechanical interaction of dental implants with the bone tissue with respect to different types of cancellous bone model. The solution is associated with a broader range of dental-implant-related clinical problems. The effective processing of data from CT and micro-CT devices enables achieving a high level of computational models that include detailed trabecular bone architecture as well as non-homogeneous material property distribution. Using such models allows local biomechanical analyses that are inevitable for better understanding of bone-implant contact (BIC) mechanisms

Biomechanical study of the bone tissue with dental implants interaction

The article deals with the stress-strain analysis of human mandible in the physiological state and after the dental implant application. The evaluation is focused on assessing of the cancellous bone tissue modeling-level. Three cancellous bone model-types are assessed: Non-trabecular model with homogenous isotropic material, nontrabecular model with inhomogeneous material obtained from computer tomography data using CT Data Analysis software, and trabecular model built from mandible section image. Computational modeling was chosen as the most suitable solution method and the solution on two-dimensional level was carried out. The results show that strain is more preferable value than stress in case of evaluation of mechanical response in cancellous bone. The non-trabecular model with CT-obtained material model is not acceptable for stress-strain analysis of the cancellous bone for singularities occurring on interfaces of regions with different values of modulus of elasticity

Hydroxyapatite coating influence on performance of bone-implant contact in cranioplasty: Finite element study

The work has been supported by the research project FSI/STI-J-18-5337.The aim of this study is to analyse mechanical performance of cranial Titanium implant with and HA coating and to compare it with ordinary used implant materials (PMMA, PEEK and Titanium alloy without coating) using computational modelling

Micro finite element analysis of dental implants under different loading conditions

Osseointegration is paramount for the longevity of dental implants and is significantly influenced by biomechanical stimuli. The aim of the present study was to assess the micro-strain and displacement induced by loaded dental implants at different stages of osseointegration using finite element analysis (FEA). Computational models of two mandible segments with different trabecular densities were constructed using microCT data. Three different implant loading directions and two osseointegration stages were considered in the stress-strain analysis of the bone-implant assembly. The bony segments were analyzed using two approaches. The first approach was based on Mechanostat strain intervals and the second approach was based on tensile/compression yield strains. The results of this study revealed that bone surrounding dental implants is critically strained in cases when only a partial osseointegration is present and when an implant is loaded by buccolingual forces. In such cases, implants also encounter high stresses. Displacements of partially-osseointegrated implant are significantly larger than those of fully-osseointegrated implants. It can be concluded that the partial osseointegration is a potential risk in terms of implant longevity

Finite element analysis of dental implant loading on atrophic and non-atrophic cancellous and cortical mandibular bone - a feasibility study

The first aim of this study was to assess displacements and micro-strain induced on different grades of atrophic cortical and trabecular mandibular bone by axially loaded dental implants using finite element analysis (FEA). The second aim was to assess the micro-strain induced by different implant geometries and the levels of bone-to-implant contact (BIC) on the surrounding bone. Six mandibular bone segments demonstrating different grades of mandibular bone atrophy and various bone volume fractions (from 0.149 to 0.471) were imaged using a micro-CT device. The acquired bone STL models and implant (Brånemark, Straumann, Ankylos) were merged into a three-dimensional finite elements structure. The mean displacement value for all implants was 3.1±1.2 µm. Displacements were lower in the group with a strong BIC. The results indicated that the maximum strain values of cortical and cancellous bone increased with lower bone density. Strain distribution is the first and foremost dependent on the shape of bone and architecture of cancellous bone. The geometry of the implant, thread patterns, grade of bone atrophy and BIC all affect the displacement and micro-strain on the mandible bone. Preoperative finite element analysis could offer improved predictability in the long-term outlook of dental implant restorations