Applied Mechanics and Materials Vol. 621

Abstract: Cylindrical pressure vessels with circular cross section are commonly used in the construction of various pressure apparatus; however in certain cases other cross sections are applied. The vessels with rectangular and elliptical perpendicular cross section are of the main interest and certain formulas for their calculations are stated in the respective codes [1, 2]. In these appliances flat ends of various shapes are usually used as the vessels caps. Similarly, as for the cylindrical boilers, flat end plates with stress relieve grooves are recommended. Like in the flat ends for cylindrical pipes certain variation of the groove parameters is possible but again no clear suggestion is given how to choose the optimal groove parameters providing the minimum stress concentration [3]. In this paper the numerical analysis and optimization of the admitted by code [1] groove parameters is presented for the pipe with the rectangular cross section subjected to the internal pressure.

Abstract: Removed at authors request

Abstract: Dynamic analysis of elastic body for plate and shell is important and difficult to solute. The convolution-type weighted residuals method is a new method, which is applied to solve dynamic problems. And the method of convolution-type point collocation is applied to solve dynamic problems of thin shell. An effective approach to structural dynamic analysis of thin shell is provided.

Abstract: This paper proposes a 3D computational Finite Element model of a shear wall test that includes the test device with the tested concrete slab. A modified Drucker-Prager model was used for the modelling of the nonlinear behaviour of the concrete. The condition of plasticity is formed from two criteria with which it is possible to realistically describe the strength of concrete under pressure, tension and shear stress. The simulation results are compared to measured data.

Abstract: In this work, a new solution of load control valve based on a hydraulic coupling two-stage principle is proposed. A detailed mathematical model of the valve has been developed. According the model, the steady-state and dynamic characteristics have been studied. The steady state study shows that the valve has an ideal piloted opening function which is not affected by the load pressure or back pressure alteration. Through an insightful analysis based on the linearized model, the dynamic study reveals that the main stage respond as a 1^st order model which is smooth and fast enough compared to the pilot stage, while the pilot stage can be simplified as 2^nd order model which may cause a problem of oscillation or overshot. The transition response of the valve is mainly decided by the pilot stage. Through the study of various parameters, the diameter of the orifice on the pilot piston shows its efficient influence in adjusting the poles in the pilot stage without affecting the steady state operation of the valve. An optimization based on root locus method is implemented and the poles have been deployed to the fastest points without oscillation.

Abstract: Severe earthquakes throughout the world show that existing masonry buildings are prone to suffer out-of-plane local-collapse mechanisms. In such mechanisms energy dissipation is mainly due to impacts against the remainder of the structure. Using data from an experimental campaign on free-rocking walls, estimation are suggested for the coefficient of restitution in both two-sided (façade resting on a foundation) and one-sided (façade adjacent to transverse walls) rocking. Both brick and tuff elements are considered, and the relevance of test repetition and wall height-to-thickness ratio is addressed.

Abstract: Mast structure is made of soft tow rope and slender shaft, whose large deformation and strong nonlinear dynamic characteristics makes very complicated. Under normal design, construction proportion of cases occurring high mast damage is rare in civil construction. In this paper, by choosing the initial parameters of multilayer guyed mast structure, and to study the impact on the performance of the mast structure.

Abstract: The topic of this paper is the description of different approaches to numerical simulation of prestressed concrete in computational system ANSYS 14.5. Due to increasing popularity of the numerical simulations, the paper aims to divide and describe simple methods and related aspects of modeling prestress on the finite element level. The paper contains three main part: the analytical solution, the numerical solution and the final comparison of the results. The obtained numerical results proved applicability of FEA for solving problems of prestressed concrete elements.

Abstract: The calculating algorithm for Cutter Contacting (CC) paths is proposed in this article to enhance machining precision of complex surfaces with a flat-end cutter. With the style of coordinate transformation, effective cutting shape and equavellent machining radius of a flat-end cutter had been calculated and deduced, and the step-over distance formed by two adjacent CC paths were also obtained. The corresponding NURBS path of tool center points including knot vector and controlling points was obtained from the cutter contacting points.The parameter increment along the CC path interval direction was calculated by using geometric analysis of the local area of CC point.

Abstract: In this article, a new method with Non-Uniform Rational B-Spline (NURBS) technology is presented and realized in a location and federate controlling system. In the method, the tool paths and the cutter locations (CL) were represented into NURBS curves based on the same knot vector. The above CL data was firstly calculated and then transformed to five motion commands of five axes of machine through the real-time post-procession algorithm. The acceleration/deceleration controlling method is also presented to avoid the impact of machine. The proposed 5-axis spline interpolation method is realized and the experimental result of machining shows that the method is valid.