1,721,065 research outputs found
The Derivation of the Domain Boundary Integral Equation Governing the Material non Linearity of Heterogeneous Spongy Structures
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Actomyosin contractility and buckling of microtubules in nucleation, growth and disassembling of focal adhesions
No full textBuilding up and maintenance of cytoskeletal structure in living cells are force-dependent processes involving a dynamic chain of polymerization and depolymerization events, which are also at the basis of cells’ remodelling and locomotion. All these phenomena develop by establishing cell–matrix interfaces made of protein complexes, known as focal adhesions, which govern mechanosensing and mechanotransduction mechanisms mediated by stress transmission between cell interior and external environment. Within this framework, by starting from a work by Cao et al. (Biophys J 109:1807–1817, 2015), we here investigate the role played by actomyosin contractility of stress fibres in nucleation, growth and disassembling of focal adhesions. In particular, we propose a tensegrity model of an adherent cell incorporating nonlinear elasticity and unstable behaviours, which provides a new kinematical interpretation of cellular contractile forces and describes how stress fibres, microtubules and adhesion plaques interact mechanobiologically. The results confirm some experimental evidences and suggest how the actomyosin contraction level could be exploited by cells to actively control their adhesion, eventually triggering cytoskeleton reconfigurations and migration processes observed in both physiological conditions and diseases. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10237-022-01584-3
Influence of actual plastic hinge placement on the behavior of ductile frames
No full textThe ultimate load and collapsing modes of steel frames under combined vertical and horizontal forces are investigated through finite element (FE) modelling and limit analysis. Consideration is given to a frequently overlooked problem which is the kinematics arising from the actual rotation of the plastic hinges under axial force and bending moment. This fact draws attention to the necessity of a careful assessment of the limit analysis approaches, a fact that might be seen as somewhat in line with the outcome from famous paradoxes, such as the one by Stüssi and Kollbrunner (1935), which can only be solved by making reference to both elastic and plastic deformations. As a result, it can be shown that in such a manner, it is possible to obtain a handy tool capable of competing with much more computationally expensive methodologies. The approach may be relevant to practising engineers dealing with code prescriptions and standardization committees
Bounds for plastic multipliers in combined loadings: applications to solids and structures
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