The aim of the paper is modal condensation of a system which represents bladed disk. These kinds of systems are mainly used in steam turbines what is the topic of the article. The model of the bladed disk is based on decomposition into a disk subsystem and a blading subsystem. The finite element method is used for modeling of the both subsystems. All influences of steady-state rotation are respected as centrifugal forces, gyroscopic effects, centrifugal stiffening of blades and dynamic softening. Blades are modeled by using ID elements and the disk is modeled by using 3D hexahedral elements. Modal condensation is applied to a disk subsystem. Different levels of the condensation are presented and compared on a testing bladed disk. and Obsahuje seznam literatury
The paper deals with design optimization of a capacitive micromachined switch consisting of a thin membrane suspended over a central conductor. The aim is to achieve as small necessary electrostatic pull-in force as possibble while ensuring fast switching. Optimum parameters are searched using fast linear and nonlinear beam models verified by the finite element method. and Obsahuje seznam literatury
This work presents the procedure of a computational model of pathological hip joint allowing a simple modification of individual parts of the model according to the planned course of femoral and pelvic osteotomy. Both presented models were subjected to strain-stress analysis by a finite element method using the ANSYS program system. The obtained results are compared with physiological hip joint results and the feasibility of planned osteotomy is evaluated based on selected mechanical parameters. The conclusions are consulted with surgeons and possible corelations with clinical results are searched for. and Obsahuje seznam literatury
The paper is focused on computational modeling of elbow articulation with radial head replacement. The main part of the project is aimed towards the creation of computational model of suitable partial endoprothesis of proximal part of the radial bone tissue which would keep the function of the elbow articulation while replacing the distance created by resection. The geometrical and computational models of radial head replacements and elbow joint were created. Computational models with these implants were compared with given physiological state of elbow articulation. The influence of friction and material characteristics of bone tissue and cartilage on changes in contact pressure (and therefore to the abrasion) were analyzed using those models. and Obsahuje seznam literatury
In case of a traumatological contusion of the elbow joint the bearing surfaces of the proximal end of the radius are damaged or broken off, resulting in their surgical removal. This operation does not make the elbow connection non-functional; however, it results in shortening the antebrachial bones, causing unpleasant pain in the patient‘s wrist. The medical team of the Traumatological Hospital in Brno has asked us to come up with a partial radio-humeral alloplasty, eliminating such adverse effects.
The influence of the steel strip cracking at the wound part of the high pressure compound vessel on the stress, strain and vessel safety has been investigated. An equivalent orthotropic material model with the zero tangential elasticity modulus Et has been utilised to describe this phenomenon. The stress and strain analysis was carried out by means of the problem oriented finite element method (F EM) code PROKOP [2]. The damaged strip packet of thickness 10 mm at any radial position influences negatively the vessel safety. The steel strip cracking near the inner winding radius is more dangerous than the cracking near the outer radius. and Obsahuje seznam literatury
The influence of water environment on natural frequencies of a Francis pump-turbine runner with the shaft is analyzed. The computations are executed by ANSYS program package based on finite element method. The fluid ‘equivalent mass‘ matrix concept is used. For solution, the Euler approach is used. Obtained natural frequencies and vibration mode shapes of the turbine runner with shaft in vaccum, in air and in water are presented. Computed natural frequencies and vibration mode shapes of the turbine runner with shaft in vacuum are compared to computed natural frequencies and vibration mode shapes of the turbine runner without shaft. and Obsahuje seznam literatury