A cytoskeletal network contributes significantly to intracellular regulation of mechanical stresses, cell motility and cellular mechanics. Thus, it plays a vital role in defining the mechanical behaviour of the cell. Among the wide range of models proposed for dynamic behaviour of cytoskeleton, the soft glassy rheology model has gained special attention due to the resemblance of its predictions with the mechanical data measured from experiment. The soft glassy material, theory of soft glassy rheology and experiment on cytoskeleton has been discussed, which leads to a discussion of the unique features and flaws of the model. The soft glassy rheological model provides a unique explanation of the cytoskeleton ability to deform, flow and remodel. and Obsahuje seznam literatury
The paper presents results of mechanical testing of soft tissues (arterial walls) under biaxial stress conditions and analysis of the influence of some factors, such as specimen location, reconditioning, etc. Soft tissues are pseudoelastic materials, modelled mostly as hyperelastic, either isotropic or anisotropic ones. Therefore multiaxial (biaxial) mechanical tests are required for a credible identification of their mechanical parameters. As living tissue proporties change with time after excision and exhibit also viscoelastic behaviour, a much more specialized equipment is needed to perform biaxial tests of soft tissues. A test rig for biaxial tests is presented in the paper and a pronounced influence of stress state character on the specimen behaviour during several first cycles is analyzed. and Obsahuje seznam literatury
This paper presents a brief review of selected approaches used for computational modelling of bimaterial failure and for evaluation of interface failure resistance. Attention is paid to the approaches that assume absence of initial interface crack. The applicability of such approaches to rubber-steel interface failure evaluation is discussed in the paper. The approach based on the so called ‘cohesive zone model‘ is preferred and demonstrated by an example of computational modelling of rubber-steel interface failure during a peel-test. The results of peel-test computational modelling are presented. The influence of cohesive zone element number on the results is also analysed. The results are consistent with experimental data. and Obsahuje seznam literatury
The tensegrity framework consists of both compression numbers (struts) and tensile members (tendons) in a specific topology stabilized by induced prestress. Tensegrity plays a vital role in technological advancement of mankind in many fields ranging from classification of elementary cells of tensegrity structures including rhombic, circuit and Z type configuration. Further, different types of tensegrities created on the basis of these configurations are studied and analysed, for instance Tensegrity prism, Diamond tensegrity, and Zig-zag tensegrity. The Part II focuses on application of the tensegrity principle in construction of double layer high frequency tensegrity spheres. and Obsahuje seznam literatury
The paper continues the overview of tensegrity, part I of which deals with the fundamental classification of tensegrities based on their topologies. This part II focuses on special features, classification and construction of high frequency tensegrity spheres. They have a wide range of applications in the construction of tough large scale domes, in the field of cellular mechanics, etc. The design approach of double layer high frequency tensegrities using T-tripods as compresion members for interconnecting the inner and outer layers of tendons is outlined. The construction of complicated single and double bonding spherical tensegrities using a repetitive pattern of three-strut octahedron tensegrity in its flattened form is reviewed. Form-finding procedure to design a new tensegrity structure or improve the existing one by achieving the desired topology and level of prestress is discussed at the end. The types of tensegrities, their configurations and topologies studied in both parts of this overview paper can be helpful for their recognition in different technical fields and,consequently, can bring their broader applications. and Obsahuje seznam literatury
This paper deals with experiments and computational simulations of composite material with hyperelastic matrix and steel fibres; the main goal is to compa and Obsahuje seznam literatury
The paper deals with stress concentration in inclined bars and beams, where the shoulder radius is often not prescribed in the detail drawings. The commonly accepted notch definition as a stepwise change of the beam cross section, as well as a lack of
nomograms or other data on stress concentration in inclined shoulders in the available literature ([1], [2], [3]) support the assumption of negligible stress concentration in inclined shoulders. Several failures of shaft-like components with inclined shoulders made us to investigate the stress concentration in these shoulders. Computational modelling confirmed a rather high stress concentration even in shoulders with a very low inclination β angle. Even in the case of β = 30°, the stress concentration factor is only slightly lower than in a comparable perpendicular (β = 90°) shoulder. Therefore nomograms for evaluation of stress concentration factors in inclined bar and beam shoulders under basic loading types were created and published in the paper.
The paper continues the description of constitutive behaviour of matters, the overview of which was presented in the previous part of this paper (Part I - basic and simple constitutive models). The definition and systemization of constitutive models was presented there and basic and simple models were described in detail. In the same systemic approach, combined constitutive models of materials (solid matters) are presented in this paper (Part II). It analyzes the more complex types of constitutive behaviour and presents a comprehensive overview of their responses in standard tension tests (stresses as functions of strain magnitude and strain rate), as well as the simplest mathematical interpretations of viscoelastic, elastic-plastic, viscoplastic and elastic-viscoplastic matters are presented, except for various types of anisotropic materials and their constitutive models (all the models are presented as isotropic only). On the base of both of these papers, the chapter on constitutive models was published in [1]. and Obsahuje seznam literatury
The paper presents a systemic overview of constitutive models, i.e. mathematical or graphical representations of responses of a matter iniciated by its activation coming from its surroundings (especially stress- or strain-controlled loadings in mechanics). Various states of matter showing different behaviour are related with different distances among particles of the matter and their mutual movements. However, in oppostie to the previous centuries, when different approaches and methods were developed and used for description of various types of matters (in solid mechanics, hydromechanics, thermodynamics etc.), recently more and more often solid mechanics meets materials showing some features of fluids (e.g. creep, flow), and interactions of matters in different states (e.g. solid-liquid) need to be solved as well. The presented paper, together with another consequent one (Part II), creates a set of two related articles aiming at facilitating you the orientation in various types of constitutive equations. It presents graphical representations of basic mechanical resposnes (stress as a function of strain magnitude and strain rate, creep stress relaxation), as well as their simplified mathematical substantiation. Some more complex types of constitutive models will be presented in part II. On the base of these papers, the chapter on constitutive models was published in [1]. and Obsahuje seznam literatury