PAMM
The results of the presented work are due to the study of the applied problem of the rigid body motion in a resisting medium. More earlier the complete lists of transcendental first integrals expressed through a finite combination of elementary functions were obtained. This circumstance allowed the author to perform a complete analysis of all phase trajectories and highlight those properties of them...
The purpose of this contribution is to compare the shear and the normal stresses in two different types of bioreactors. In the first one (SBR), the granules are generated by liquid and bubbles flow, whereas in the second one (SF‐SBR), the shear rate is achieved by installing a rotating cylinder inside the reactor. Such shear flow can be applied for anaerobic process in the wastewater treatment. The...
Flow around the two‐dimensional hill is of great interest in engineering application, namely in transport and dispersion of pollutants in atmosphere. A case of polynomial shaped 2D hill with the line source of tracer gas has been studied in detail. Experimental study of both, the time‐averaged velocity field and the binary‐mixture concentration field has been done. (© 2010 Wiley‐VCH Verlag GmbH &...
A fluid‐structure mathematical model usually includes parameters whose actual values are known only approximately or can vary around some reference values. The objective of the sensitivity analysis is to determine quantitatively the behavior of the responses of a fluid‐structure system locally around a chosen point of the trajectory in the phase‐space of parameters and dependent variables. In this...
The present paper is the continuation of earlier publications with stack of piezoelectric plates. This work is an author's idea of application for generating characteristics of piezoelectric systems. The presented program, called Piezo3D, allows for generation a single piezoelectric plate graphs as well as complex, free and bonded systems. An additional advantage is the ability to obtain the 3D graphs,...
We treat coupled electromechanical problem of finite deformations of piezoelectric shells with the help of the direct approach. A shell is considered as a material surface with mechanical degrees of freedom of particles and with an additional field variable, namely electric potential on the electrodes. This results both in the nonlinear system of equations of piezoelectric shells and in the appropriate...
The main aim of this work is to present results of the mechanical system's analysis based on the exact and approximate Galerkin's methods. The considered system is the flexural vibrating one‐dimension bending beam. The exact and approximate method were used to assign the dynamic flexibility of the considered system and results of this work were juxtaposed to verify the approximate method's accuracy...
Enhanced numerical methods for the solution of three‐dimensional nonlinear electromechanically coupled boundary value problems are considered. A vector potential finite element formulation with return mapping algorithm and consistent tangent operator is developed. The accuracy and robustness of the algorithms are assessed with the help of numerical examples concerning a ferroelectroelastic analysis...
A monolithic approach to fluid‐structure interactions based on the space‐time finite element method is presented to investigate stress states in silos filled with granular material during discharge. The thin‐walled silo‐shell is discretized by continuum based, mixed‐hybrid finite elements, whereas the flowing granular material is described by an enhanced viscoplastic non‐Newtonian fluid model. To...
To study the behaviour of the complex failure mechanisms in thermal barrier coatings, a simplified model system is used to reduce the number of system parameters. The artificial system consists of a bond‐coat material (fast creeping Fecralloy or slow creeping MA956) as the substrate with a Y2O3 partially stabilized plasma sprayed zircon oxide TBC on top and a TGO between the two layers. A FEM simulation...
In this contribution, stabilized mixed finite tetrahedral elements are presented in order to avoid volume locking and stress oscillations. Geometrically non‐linear elastic problems are addressed. The mixed method of incompatible modes is considered. As a key idea, volume and area bubble functions are used for the method of incompatible modes [1], thus giving it the interpretation of a mixed finite...
In the present work, a mixed finite element based on a modified least‐squares formulation is proposed. Here, we consider the time‐dependent equations for quasi‐incompressible elastodynamics under small strain assumptions. The main goal is to obtain an accurate approximation of both displacements and stresses in particular for the lowest‐order element. Basis for the element formulation is a weak form...
High performance ceramics have found their way into many highly challenging engineering tasks. For example silicon nitride is one of the best choices, if a material for demanding applications like metal forming and cutting is required. Due to the brittle nature of these hard and strong materials it is useful to know about thermal residual stresses, which can arise during the sintering process. In...
The creation of a holistic model which is able to represent the global dynamic behavior as well as local effects in certain regions leads to finite element models consisting of domains with different local meshes and a combination of different model dimensions. The different model domains have to be coupled such causing in an additional coupling error. The Arlequin method seems to be a flexible tool...
Stiffness modifications in engineering structures, for example due to damage and cracking, will inevitably also lead to changes in deformations, internal forces, natural frequencies and mode shapes of the structures. In this paper, an efficient and simple method for sensitivity analysis of cracked or weakened structures under time‐harmonic loading is presented. The method is based on a comparison...
Crack analysis of linear coupled thermoelasticity in two‐dimensional, isotropic, non‐homogeneous and linear elastic functionally graded materials subjected to thermal shock is performed by using a boundary‐domain element method. The material parameters are assumed to be continuous functions of the spatial coordinates. Fundamental solutions of linear coupled thermoelasticity for the corresponding isotropic,...
The effective properties of fiber reinforced materials depend strongly on the properties of the interface between the phases. In the particular case of glass fiber reinforced thermoplastics, this bonding is inherently weak and needs to be improved, e.g., by addition of compatibilyzers. Reliable experimental setups are needed in order to investigate the effects of such additives on the interface properties...
The effective treatment of brain diseases, such as malignant brain tumours, is generally constricted by the controlled contribution of therapeutic agents. Novel brain tumour therapy proceeds from a direct infusion of the drug into the extra‐vascular space of the nervous brain tissue (convection‐enhanced delivery). This is carried out using catheter to bypass the blood‐brain barrier, which effectively...
The present study is concerned with the development of an enhanced probabilistic model for cleavage assessment of ferritic steels. An enhanced model for the probabilistic cleavage fracture assessment has to consider the conditions for both, nucleation and propagation of micro defects. Hence, a propagation based model is enhanced by a combination of the local plastic strain and the local stress triaxiality...
The aim of the present paper is to account for the growth of fiber which is observed in a cell‐seeded material stimulated in a bioreactor. For this purpose, the change of mass is considered in the balance laws, and the deformation energy is assumed to be a function of varying mass and the Helmholtz free‐energy. Fiber growth at the microscopic level causes a macroscopic change of the material's mechanical...