This thesis deals with stress analysis of tandem platform trailer TVL10. The first part is devoted to description of trailers and their parts. The second part presents and evaluates the results of measuring acceleration and vibration of the trailer, and it describes the concrete chassis of a tandem trailer. There is included an analysis of the existing structure, design modifications and stress calculation and evaluation of newly designed chassis structure. The thesis is developed in cooperation with PANAV, a.s.

This diploma thesis deals with an atypical heated bed for FDM 3D printer. It presents the most commonly used ways of heating and the chosen variant of the heated beds are realized by powerful resistors. There are also discussed three ways of placement of resistors on the desktop motherboards that are modeled in Autodesk Inventor Professional 2016 and exported to Autodesk Fusion 360, where FEM calculations are made. Optimal alternative is made and tested. The test results are compared with the results of thermal simulations in Autodesk Fusion 360.

The present paper deals with the problematics of the design and technology of planar microelectronic structures for the hign frequency band. These structures were realised on the Department of Microelectronics and their properties were measured on the Department of Radioelectronics. The part of this work is also simulation of some microelectronic structures, where for these simulations the design and simulation tool Ansoft Designer and the FEM tool ANSYS was used. The attention is paid to the discrete devices (coils and capacitors) as well as to the more complex structures (frequency filters). The paper yields the new findings in the field of the design and technology of the discrete components as well as of the more complex systems, these findings can be used as the basis for another research of practical applications.

The final thesis „Explicit and Implicit methods in nonlinear dynamics“ deals with the issue of geometrical and physical nonlinear analysis of structures exposed to seismic loading by the methods of direct integration of equations of motion. Solution by the explicit and the implicit method is compared for three material models. While the differences between the results of the explicit method and the implicit Newmark method are small as expected, the differences are substantial between the results of different material models. However, these differences are explained and they are in full concordance with the theoretical assumptions for the pertinent material models. The conclusion of the final thesis is check of correctness of the results of the new module of the program system RFEM for both tested numerical methods and all three analyzed material models. (linear elastic, plastic Drucker-Prager and the Mazars damage model). With sufficient precision of results, both explicit and implicit numerical methods showed to be suitable for seismic analysis. The implicit method can provide several times faster calculation than the explicit one, but the determination of the optimal time step is problematic and time consuming, so the suitability of use of both methods for seismic analysis is comparable.

Using the Navier-Stokes equations along with a continuity equation, a one-dimensional model is developed to describe the spin coating process of thin polymeric films. The resulting model is a system of a parabolic partial differential equation coupled with an integral equation as well as with an ordinary differential equation describing the motion of a moving boundary. Viscosity and diffusivity are allowed to be varied in the model. To be able to perform the finite element approximation of the model equations, the moving boundary is fixed. Then the finite element method is applied along with the so called Method of Lines resulting in a semi-discrete problem, a large system of ordinary differential equations which is then solved with MATLAB. We present an existence and uniqueness result what concerns the semi-discrete solutions. Finally, we illustrate numerically the behavior of the solutions to our model.

The thesis originates from a need to meet stricter environmental regulations for Scania, to reduce fuel consumption and emission from heavy-vehicles. Scania aims to fulfil these requirements by increasing combustion pressure and temperature. These conditions are tougher for the engine components and they shorten their lifetime. This thesis aims to improve Scania’s ability to increase the lifetime of a heavy-vehicle exhaust manifold, an engine component that collects exhaust from several engine cylinders into one pipe. This was done by conducting a material comparison and a parameter study, both used the FEM software Abaqus CAE. The material comparison consisted of three ferritic and austenitic ductile cast irons (SiMo51, SiMo1000 and Ni-resist) subjected to thermal stress. Their max stress was compared for two thermo-mechanical fatigue cases, out-of-phase and in-phase. A parameter study was also conducted to clarify the influence of thermal conductivity, thermalexpansion, Young’s modulus and yield strength on max stress for OP and IP in the exhaust manifold. The FEM simulation results from the parameter study were used to create functions that can be used to decide how to treat/process a material to minimise the stress in the exhaust manifold. They can also be used in material selection to choose a material that minimises stress. The research questions and their shortened answers can be seen below. 1. Which of SiMo51, SiMo1000 and Ni-resist produces the lowest tensile stresses? ForOP, SiMo1000 produced a slightly lower max principal stress than SiMo51. For IP, Ni-resistproduced the lowest max principal stress by a large margin. 2. How do different material properties affect the maximum stress during operation of thegiven component? Thermal conductivity has a decreasing relation to max stress. Thermalexpansion and Young’s modulus have a similar relation to max stress, stress increases forboth properties as they increase. A decreased yield strength decreases the max stress forstresses above the yield limit but has no effect on stress below it. 3. How should an objective function to minimise max stress in the component with regard to material properties be expressed? functions of OP and IP can be seen in the actual abstract.

Here we describe a finite element model of the mechanical stresses and strains involved in the growth and development of epithelial cancers, specifically pancreatic ductal adenocarcinoma (PDAC). We model a growing tumor swelling over time, modeled as fluid influx in response to changing solute concentrations. Stresses and strains are computed in surrounding material regions in response to this swelling. Further studies are conducted into the relative impacts of factors such as basement membrane thickness, stiffness, and duct radius. We observe that normal stresses are confined mostly to the basement membrane layer and hypothesize that there exists some threshold for axial stress beyond which the basement membrane ruptures and cancer is able to invade into the surrounding tissue.

<div> <div> <div> <p>This dissertation contains two parts: one part is about the error estimate for the finite element approximation to elliptic PDEs with discontinuous Dirichlet boundary data, the other is about the error estimate of the DG method for elliptic equations with low regularity. </p> <p>Elliptic problems with low regularities arise in many applications, error estimate for sufficiently smooth solutions have been thoroughly studied but few results have been obtained for elliptic problems with low regularities. Part I provides an error estimate for finite element approximation to elliptic partial differential equations (PDEs) with discontinuous Dirichlet boundary data. Solutions of problems of this type are not in H1 and, hence, the standard variational formulation is not valid. To circumvent this difficulty, an error estimate of a finite element approximation in the W1,r(Ω) (0 < r < 2) norm is obtained through a regularization by constructing a continuous approximation of the Dirichlet boundary data. With discontinuous boundary data, the variational form is not valid since the solution for the general elliptic equations is not in H1. By using the W1,r (1 < r < 2) regularity and constructing continuous approximation to the boundary data, here we present error estimates for general elliptic equations. </p> <p>Part II presents a class of DG methods and proves the stability when the solution belong to H1+ε where ε < 1/2 could be very small. we derive a non-standard variational formulation for advection-diffusion-reaction problems. The formulation is defined in an appropriate function space that permits discontinuity across element </p> </div> </div> <div> <div> <p>viii </p> </div> </div> </div> <div> <div> <div> <p>interfaces and does not require piece wise Hs(Ω), s ≥ 3/2, smoothness. Hence, both continuous and discontinuous (including Crouzeix-Raviart) finite element spaces may be used and are conforming with respect to this variational formulation. Then it establishes the a priori error estimates of these methods when the underlying problem is not piece wise H3/2 regular. The constant in the estimate is independent of the parameters of the underlying problem. Error analysis presented here is new. The analysis makes use of the discrete coercivity of the bilinear form, an error equation, and an efficiency bound of the continuous finite element approximation obtained in the a posteriori error estimation. Finally a new DG method is introduced i to over- come the difficulty in convergence analysis in the standard DG methods and also proves the stability. </p> </div> </div> </div>

Der Standard des Message Passing Interfaces (MPI) stellt dem Entwickler paralleler Anwendungen ein mächtiges Werkzeug zur Verfügung, seine Softwa- re effizient und weitgehend unabhängig von Details des parallelen Systems zu entwerfen. Im Rahmen einer Projektarbeit erfolgte die Umstellung der Kommunikationsbibliothek eines bestehenden FEM-Programmes auf den MPI-Mechanismus. Die Ergebnisse werden in der hier gegebenen Beschreibung der Cubecom-Implementierung zusammengefasst. In einem zweiten Teil dieser Arbeit wird untersucht, auf welchem Wege mit der in MPI verfügbaren Funktionalität auch die Koppelrandkommunikation mit einem einheitlichen und effizienten Verfahren durchgeführt werden kann. Sowohl fuer die Basisimplementierung als auch die MPI-basierte Koppelrandkommunikation wird die Effizienz untersucht und ein Ausblick auf weitere Anwendungsmoeglichkeiten gegeben.

In der vorliegenden Arbeit wird die Anwendung eines bereits im 2D-Fall benutzten Mechanismus zur MPI-basierten Koppelrandkommunikation auf das 3D-FEM-System SPC PMPo-3D beschrieben. Insbesondere soll der Einfluss der Partitionierung auf die Laufzeit im Vergleich mit den Resultaten für das Originalsystem, fuer das entsprechende Untersuchungen bereits in durchgefuehrt wurden, betrachtet werden. Weiterhin wird ein Ausblick auf weitere Optimierungsmöglichkeiten des Verfahrens gegeben.