NEMEC, L.: Solution of truss deformations by Simulated Annealing Method (in Czech) 301 TONDL, A.: Dynamic absorber for a suspended platform 307 BILY, M., HORANSKY, P.: Non-stationary processes and their simulation in fatigue 319 KOSKA, P., KOCANDRLE, P.: Boundary integral equation approach for shape sensitivity analysis of elastic and thermoelastic solids 332 LI, Y.: Multibody dynamics approach to the working mechanism of wheel loader 354
L. NEMEC
The paper presents a nontraditional way of solving truss deformations. The Simulated Annealing Method used commonly in economy, control, etc. is now applied to a mechanical problem. An analogy between the process of annealing and process of loading of truss is used. Annealing is simulated by the Metropolis procedure from statistical mechanics (behavior of a system with many degrees of freedom in thermal equilibrium at a finite temperature is simulated), providing iterative improvements to optimal solution. The odds of our application is illustrated on simple examples. Evaluation of this approach to those problems is presented in the conclusion.
A. TONDL
A dynamic absorber is attached to a suspended platform which is kinematically excited due to the harmonic motion of the suspension points. Two alternatives of the absorber differing in the direction of the absorber motion are considered: vertical direction for System I and a horizontal one for System II. The results of the analysis are presented in diagrams showing the efficiency of both systems. The differences between both systems are discussed.
M. BILY, P. HORANSKY
The authors present definitions of non-stationary processes, discuss their appearance in nature and possibilities of assessment of non-stationary properties. Further, they present three ways of simulation of non-stationary processes exploiting either the correlation theory characteristics, closed loop countings (Rain Flow Method), and Markov chains. Based on computational and experimental results, they assess the importance of non-stationary process properties for the fatigue life estimation and formulate some practical recommendations.
P. KOSKA, P. KOCANDRLE
The structures subjected to the effects of volume forces satisfying potentiality conditions (e.g. centrifugal and gravity forces) and thermal stresses are considered. The temperature and displacement sensitivities on the general non-smooth boundary are obtained using the approach based on direct differentiation of the boundary integral equations. The resulting pure boundary expressions contain only regular integrals. Two different implementations of the approximate stress sensitivity recovery equation are discussed. Both the geometric and natural design variables are used to parametrize the free boundaries. For the two selected two-dimensional examples, the accuracy of calculated stress sensitivities is checked with analytical solutions.
Y. LI
Based on Kane's equation, a concise formulation for a general multibody dynamics system is presented in this paper. As a practical application, the dynamic analysis for the working mechanism of a wheel loader is analyzed using multibody dynamics method. The dynamic problems of the wheel loader are difficult to solve if employing a general mechanics method. After performing the dynamic analysis for a wheel loader, some new design ideas and viewpoints are proposed. This approach is meaningful to guide practical product design of wheel loader.