Vibration Protection Systems

Design and deploy advanced vibration protection systems based on elastic composites under post-buckling, with this essential reference. Methods for designing vibration protection systems with negative and quasi-zero stiffness are formulated, explained, and demonstrated in practice. All key steps of the system design are covered, including the type and number synthesis, modelling and studying of stress-strain state under post-buckling of elastic composite designs, chaotic dynamics and stability conditions, real-time dimensioning, and active motion control. In addition to coverage of underlying theory, the use in helicopters, buses, railroad vehicles, construction equipment and agricultural machinery are included. An excellent reference for researchers and practicing engineers, as well as a tutorial for university students and professors with an interest in study, development and application of alternative methods of vibration protection anywhere.

Homogenized Balance Equations for Nonlinear Poroelastic Composites

Within this work, we upscale the equations that describe the pore-scale behaviour of nonlinear porous elastic composites, using the asymptotic homogenization technique in order to derive the macroscale effective governing equations. A porous hyperelastic composite can be thought of as being comprised of a matrix interacting with a number of subphases and percolated by a fluid flowing in the pores (which is chosen to be Newtonian and incompressible here). A general nonlinear macroscale model is derived and is then specified for a particular choice of strain energy function, namely the de Saint-Venant function. This leads to a macroscale system of PDEs, which is of poroelastic type with additional terms and transformations to account for the nonlinear behaviour of the material. Our new porohyperelastic-type model describes the effective behaviour of nonlinear porous composites by prescribing the stress balance equations, the conservation of mass and Darcy’s law. The coefficients of these macroscale equations encode the detailed microstructure of the material and are to be found by solving pore-scale differential problems. The model reduces to the following limit cases of (a) linear poroelastic composites when the deformation gradient approaches the identity, (b) nonlinear composites when there are no pores and (c) nonlinear poroelasticity when only the matrix–fluid interaction is considered. This model is applicable when the interactions between various hyperelastic solid phases occur at the pore-scale, as in biological tissues such as artery walls, the myocardium, lungs and liver.

Material Geometry of Binary Composites

The constitutive characterization of the uniformity and homogeneity of binary elastic composites is presented in terms of a combination of the material groupoids of the individual constituents. The incorporation of these two groupoids within a single double groupoid is proposed as a viable mathematical framework for a unified formulation of this and similar kinds of problems in continuum mechanics.

Magnetic characterization of magnetoactive elastomers containing magnetic hard particles using first-order reversal curve analysis

The use of new types of intelligent materials is becoming increasingly widespread. These include magnetoactive elastomers with hard magnetic filling components, which offer the unique chance to adapt active and passive material properties. In this context, this paper presents an overview of the experimental results on the study of the magnetic properties of elastic composites with a magnetic hard component. First-order reversal curves, which are recorded with a vibrating sample magnetometer, are used as method to characterize the magnetic material behavior. The influence of various parameters on the process of magnetization of composites is considered, including the stiffness of the polydimethylsiloxane-based matrix polymer, the particle ratio and the particle size as well as the so-called training effect.