Attila Bojtos

Finite element analysis of the human mandible at 3 different stages of life

OBJECTIVE This study analyzed detailed models of human mandibles at 3 different stages of life with simulation of supra normal chewing forces at static conditions. METHODS AND MATERIALS Finite element analysis (FEA) was used to generate models from cone-beam computerized tomograms (CBCT) of 3 patients aged 12, 20, and 67 years, using numerically calculated material parameters. Estimated chewing forces were then applied to the simulations. RESULTS The results reflect higher elasticity in younger models in all regions of the mandible. The experimental models show that physiologic load stress and strain distributional changes of the mandible vary according to age. CONCLUSION The CBCT-based model generation used in this study provided high-quality model definition of the 3 individual patients of different ages. FEA has great potential to predict bone responses to paradigms of mechanical activity. Future applications of FEA will include surgical planning, surgical hardware testing, and the design of scaffolds and tissue-engineered constructs.

Mechanical and Electrical Testing of Electrically Conductive Silicone Rubber

Silicone rubber is an essential construction material in food industry, medicine and in some fields of mechanical engineering, because it has good mechanical, electrical, biological and other special properties. One needs to know these material properties in order to develop silicone sensors. We performed several standard measurements for rubber, like tensile strength, cyclic tensile, bending, fatiguing, stress relaxation tests etc. To investigate the electrical properties, we measured the resistance of silicone during the mechanical tests. The paper summarizes the newest results of our research in connection with mechanical and electrical properties of conductive silicone rubber.

Development and Investigation of Photoelastic Sensor for Torque Measurement

This article describes the development and the calibration of the photoelastic contactless torque sensor and it also presents the measurement of the starting torque of a disk micro motor, as a function of the rotor angle. Finite element analysis was performed to prove the functionality of the sensor and to determine its required sizes. In order to define the torque—rotor angle characteristics of the micro motor, electromagnetic simulation was also performed and the results were compared to each other.

Impedance Analysis of Silicone Rubber Filled by Electrically Conductive Nanoparticles

During the research, scanning electron microscopy, compression, tensile and frequency analysis were performed on silicone rubbers filled with conductive particles , in order to understand the electrical conduction mechanism. The distribution of the conductive nanoparticles and its relationship with the substrate was examined with scanning electron microscopy (SEM). During the SEM studies, the conductive elastomers were investigated in their deformed and original state too. The connection between the deformation and the resistivity was examined with compression and tensile tests. The impedance of the material was examined on a wide range of frequency. The correctness of the lumped parameter model that is mentioned in the literature , was examined and its parameters were determined. The dependence of the resistivity on the aspect ratio of the specimens was also investigated. The aim of this research is to make this construction material intelligent, and to use it to produce hyperelastic mechanical sensors (for strain, force, torque, ect. measuring).

Measuring of Equibiaxial Tension of Rubber-Like Materials by Optical Method

For the simulations of elastic constructions actuated by inner pressure we need for the definition of the material model parameters, the data originating from the biaxial test. The paper reviews the biaxial material testing methods, especially the bubble inflation methods. It contains a short summary of the stress analysis of the rotation ellipsoid shells in association with the bubble inflation. The paper shows a developed equibiaxial inflating test using optical measurement method. Two different methods using image processing are showed. The test result of an examined silicone rubber (MED-4930) is presented with it’s material parameters.

Examine of Mechanical Load of Silicone Rubber by Optical Methods

Silicone rubber is an essential construction material in food industry, medicine and in some fields of mechanical engineering, because it has special mechanical, electrical, biological and other special properties. Over the usage of silicone rubber as structural material, the “intelligent” behaviour is more and more important. In this case the question arises whether its optical properties change by the effect of mechanical load or deformation Can it be used like sensor, utilizing these properties The paper shows the newest result of our optical research in connection with silicone rubber and shows the possibility of its usage for optical strain and force sensor, using its birefringence.

Mechanical Testing of Tendon

This paper presents an overview about results of mechanical testing of human tendon. We are dealing with the main function of tendon and touching on typical insurance of tendon and reconstruction of them. Since the material characteristic of tendon and dynamic models of them are not known there was made a lot of uniaxial tension test and based on measuring results built up a linear lumped model for dynamic simulation using the synthesis method. As results we can already provide quantitative data about mechanical bearing capacity of tendon beside known qualitative categories. Paper shows a well working fixing technology for tendons during tension test.