The Mechanical Stability for the Hand-Arm System

The present paper contains a study regarding importance stability in the mechanical systems, mechanical systems are emerging under mechanical vibrations action, it referring especially to the human hand–arm system. Mechanical systems stability is directly influenced of the dumper and the elasticity factors. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Investigation of the mechanical properties of acrylics under conditions of creep,stress relaxation,and harmonic vibration

The dynamic and static (creep, stress relaxation) mechanical properties of various acrylics have been investigated. A relation is established between the structure and the macroscopic mechanical properties. The previous thermal history and the characteristics of the state of stress are shown to affect the nature of the relaxation processes and the mechanical properties of the acrylics. Generalized stress relaxation curves are constructed. The mechanical glass transition temperatures of the acrylics investigated are determined.Lenin Moscow State Pedagogic Institute. Translated from Mekhanika Polimerov, No. 1, pp. 157–159, January–February, 1973.     

A general modelling framework and specific mechanical approaches to simulate curing phenomena in polymers

Polymers are employed as adhesives, filling or sealing materials, among others. Within these applications, a chemical reaction (e.g. polymerization) leads the materials to cure from a liquid to a solid. In this contribution, first a general continuum mechanical modelling framework for the simulation of curing phenomena is highlighted. It takes into account the main chemical, thermal and mechanical phenomena of polymeric curing processes. Secondly, different mechanical models to capture the mechanical behaviour of polymeric curing processes are regarded. It is shown that elastic, viscoelastic and viscoplastic models at large deformations can be employed. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Transient analysis of thermo-elastic waves in thick hollow cylinders using a stochastic hybrid numerical method,considering Gaussian mechanical properties

This article attempts to study the stochastic coupled thermo-elasticity of thick hollow cylinders subjected to thermal shock loading considering uncertainty in mechanical properties. The thermo-elastic governing equations based on Green–Naghdi theory (without energy dissipation) are stochastically solved using a hybrid numerical method (combined Galerkin finite element and Newmark finite difference methods). The mechanical properties are considered as random variables with Gaussian distribution, which are generated using Monte Carlo simulation method with various coefficients of variations (COVs). The effects of uncertainty in mechanical properties with various coefficients of variations on thermo-elastic wave propagation are studied in detail. Also, the maximum, mean and variance of temperature, displacement and stresses are illustrated across thickness of cylinder in various times.     

Formulation of the material force approach for elastic and inelastic materials

Fracture mechanical investigations are important for the durability of fracture sensitive products. Fracture mechanical simulations help to shorten the product development cycle and to decrease product costs. The so-called material force approach as an efficient tool is used to determine fracture mechanical parameters for elastic and inelastic materials. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

3D finite elements to model electromechanical coupled solids at failure

This work presents an extension of newly developed 3D finite elements to model failure in purely mechanical based materials [1, 2] to electromechanical coupled materials. Following the approach suggested in [6] for the plane setting, new finite elements are developed, which in addition to resolving strong discontinuities in the mechanical displacement field are capable of modeling strong discontinuities in 3D also in the electric potential. An application to a 3D off-centered three point bending test under combined mechanical and electrical loading outlines the performance of the newly developed finite elements. (© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Experimental Feasibility Study for Guided Wave Propagation

The paper presents the work on Structural Health Monitoring (SHM) which is now one of the most interesting subjects. Guided propagation of mechanical waves in elastic bodies can be applied in analogy to active phased radar antennas for electromagnetic waves. An array of bonded piezoelectric transducers can generate directed mechanical waves. In the current state of this work experiments on a beam are conducted in order to verify a mathematical model based on integral transform methods. Further experiments for plates and laminates have been designed and checked for feasibility of the mechanical and the electrical implementation. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Extended solid solubility for Al-W binary system by mechanical alloying

Al_1-XW_X(x = 0.1, 0.2, 0.5, 0.9) powders have been prepared by mechanical alloying of the elements in a planetary ball mill. The structure and morphology of the milled powders were investi gated using X-ray diffraction and electron microscopy. The solubility of Al in W is greatly extended, even more than 50%. The results are analyzed using embedded atom method (EAM) according to the scheme of mechanical alloying extending solid solubility. The theoretical results are in good agreement with the experimental     

Mechanical properties of cold sprayed Titanium and Nickel based coatings

Cold spray is an innovative coating technology. Very fine particles are accelerated, then sprayed on a substrate in condition very far from material melting. The unique mechanical properties experienced by the sprayed material are due to the severe plastic deformation acting during particle impact. In the present paper, the microstructural and mechanical behavior of Ti- and Ni-based nanocomposites coatings produced via cold spray are presented. (© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Cellular articular cartilage replacement tissues: Modeling and analysis

Long-term studies reveal that mechanical stimulation causes growth and remodeling phenomena within biological tissues. The main aim of this research is to fully understand and control these phenomena. For accomplishing that, two steps are considered: first, we determine a suitable numerical model based on different approaches by a comparative study using experimental validations, and second, investigate the mechanical properties of the tissue specimens after a remodeling process. We start with the first step by choosing a convenient model that mimics the biotissue for running the numerical simulations in the second step. There are different models available that determine the mechanical properties of soft replacement tissues seeded with human chondrocytes in modern medical applications. It is our objective to achieve a common methodology of theory and experiments that allows the determination of the mechanical properties of the native material. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Modelling the interaction between athlete and sports surfaces

Sports surfaces are often seen as one possible factor for sports injuries as the vertical ground reaction force (VGRF) depends not only on the athlete's movement but also on the mechanical properties of the ground. Therefore, the athlete-surface-interaction has to be analysed in order to minimize the loading on the athlete. The aim of this work is to understand the behaviour during landing and the associated impact forces during ground contact. Thus a simplified mechanical model is presented. Results for feasible surface material parameters are identified. A first assumption of the effect of the VGRF is presented. (© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Structural sliding equations for the tracking control of mechanical systems with active structure

The term of active structure is herein used (instead of variable structure) to emphasize that one deals with mechanical systems, some mechanical parameters of which (such as mass, inertia, rigidity) can be varied in time to account for environmental variations. One then has an internal structural control in addition to the usual external one in the form of forces or torques. By using a well-known classical result in physics, which characterizes a mechanical system by its Lagrangian only, one can obtain a new class of physically meaningful sliding equations for these systems. They are less severe regarding the mechanical constraints on the system, and they lower the amplitude of the chattering phenomenon. These systems can be controlled in a straightforward way by means of Barbashin-Utkin's variable structure technique.     

Magneto-Sensitive Elastomers: An Experimental Point of View

Magneto-sensitive elastomers (MSEs) are smart materials changing their shape and mechanical properties in the presence of a magnetic field. Focussing on model systems, silicone based MSEs are prepared by a multi-step mixing process and characterised using a rotational rheometer (plate-plate). Data obtained by relaxation tests is used to set-up a material model coupling the theories of viscoelasticity and magnetoelasticity. The behaviour of MSEs in quasi-static and dynamic mechanical shear experiments can be successfully predicted by the analytical model using parameters received by fitting the transient experiments. The model is validated for small shear deformations (γ = 0.02) and low magnetic fields (𝔹 = 0.2 T). (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Cardiorespiratory dynamics during transitions between mechanical and spontaneous ventilation in intensive care

Life support devices (e.g., heart pacemakers, ventilators, dialysis machines) are commonly thought to affect mainly their target organ system. This preliminary study attempts to determine the extent to which mechanical support of one organ system (lungs by mechanical ventilator) affects functions of other systems (heart and blood vessels). We studied changes in cardiorespiratory interactions and in dynamics of cardiovascular system during scheduled transitions (spontaneous breathing trials, SBT) between mechanical and spontaneous ventilation in critically ill patients. This initial study population consisted of 13 patients admitted to a surgical intensive care unit (ICU) following surgery, trauma, or complications who were judged candidates for liberation from the ventilator. We collected continuous respiratory, cardiac (ECG), and perfusion (blood pressure and pulse oximetry) signals of mechanically ventilated patients before, during, and after SBT. The data were analyzed using spectral analysis, phase dynamics, and entropy measures. We found that the mechanical ventilation not only drives lung dynamics but also affects the dynamics of cardiac and vascular systems. Spontaneous cardiovascular rhythms are entrained by the mechanical ventilator and are drawn into synchrony. Sudden interruption of mechanical ventilation typically leads to rapid desynchronization. This synchronization is restored upon reinstitution of mechanical ventilation. The initial data suggest that therapies intended to support one organ system may propagate unanticipated effects to other organ systems. Moreover, sustained therapies may disturb mechanisms that promote natural synchronization and variability and thereby adversely affect recovery of normal organ system interactions. We suggest that new measures and displays of synchronization not only could provide insight into the organ–organ coupling but also could yield information to optimize the function of devices used to support the critically ill patient. © 2008 Wiley Periodicals, Inc. Complexity, 2008     

XFEM-modelling of stationary magnetic and coupled magneto-mechanical boundary value problems

To analyse a composite material with magnetically switchable stiffness properties, the coupling between the magnetic and the mechanical field has to be considered. Here the mechanical as well as the magnetic problem are computed using the eXtended Finite Element Method (XFEM). After a brief introduction of the framework, some results are presented focusing on the ability to calculate correct loads and displacements as well as on convergence rates. (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Comparison of methods of investigating the components of the elongation of textile fibers

Resolving the elongation of textile fibers into its components (rapidly disappearing, slowly disappearing, and residual) provides valuable information on the mechanical properties and makes it possible to predict a series of mechanical characteristics of the fabrics into which they are made. The optimal methods of determining these components are established.Moscow Textile Institute. Translated from Mekhanika Polimerov, No. 3, pp. 444–450, May–June, 1972.     

Mechanical Synchronization in Dual-Rotor Vibroactuator

In the present work the mechanical behaviour of a dual-rotor vibrotactor has been investigated with special attention to its stationary motions and their linear stability. After the introduction of the used mechanical model, the formulae for the stationary motions are given, and characteristic stablity charts are presented. The linear stability is investigated for uncontrolled and controlled system as well. (© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Theoretical and experimental investigation of cartilage replacement material for medical applications

Soft tissues are commonly applied in surgery to replace the injured articular cartilage. Many biological researches were carried out through mechanical and histological experiments. They focus on the function, degeneration and regeneration of the articular cartilage and fibrocartilage. The aim of the presented work is to develop a method to characterize the mechanical properties of different kinds of soft tissues and to trace the evolution of elastic properties in implants during the remodeling process. (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Enhancement of the micro mechanical basis for local approach cleavage models

The present study is concerned with the investigation of the micro mechanisms of micro defect nucleation in bainitic steels in order to provide an enhanced basis for probabilistic cleavage models. By a micro mechanical modelling of the cleavage initiation process the effects and the interactions of the relevant parameters can be identified. For this purpose Representative Volume Elements (RVE) of the micro structure are utilised, accounting for both, the grain structure as well as the brittle particles at the grain boundaries. The RVE's are loaded based on the local mechanical field quantities determined numerically at the cleavage origins of different fracture mechanics specimens. (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)