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Numerical models of a valve system used in railway hydraulic dampers

Woźniak M.

Journal of Achievements in Materials and Manufacturing Engineering

2015

Vol. 73, nr 2

190--198

Purpose: The aim of this paper is to develop and validate a linear and nonlinear numerical 2/3D models of the spring washer stack and a system model of an entire hydraulic damper. Design/methodology/approach: Three types of numerical models are investigated. Linear and non-linear 2D models developed in Matlab program, and 3D nonlinear model developed in Ansys software. Findings: The system model of entire hydraulic damper and detail numerical 2/3 D model of the spring washers stack including the boundary conditions for simplified and advanced analysis were developed. Research limitations/implications: It is important to provide a model functionality allowing for calculation of spring washer stacks groups having the opening limiter. Spring washer stack stress and opening characteristics vs. applied pressure are determined with simplified analytically derived model and full 2D model including almost all significant forces and moments in a stack of circular plates. An advantage of a simplified spring washer stack model is possibility of its rapid engineering calculations, e.g. performed in Matlab. Practical implications: The valve model allows to determine the critical von Misses stress level and fatigue critical limit in elastic components of a valve system. Damper force and valve durability expressed in life-cycles are the optimization criteria considered during selection and tuning of a valve system. Originality/value: A new valve system was developed in two versions, i.e. simplified and advanced. The model allows durability prediction at the design stage reducing the testing costs of low-performance valve systems.

Simplified and advanced models of a valve system used in shock absorbers

Czop P., Sławik D., Śliwa P., Wszołek G.

Journal of Achievements in Materials and Manufacturing Engineering

2009

Vol. 33, nr 2

173-180

Purpose: The aim of this paper is to develop a model of a valve system applicable for strain and stress prediction. Design/methodology/approach: The analytical and numerical approaches are presented to provide an overview for available methods and prediction accuracy. Findings: An equivalent numerical model of a disc valve system of different complexity was developed and discussed. Research limitations/implications: It is important to provide a model functionality allowing for calculation of disc stacks supported by a coil spring and stack settings having the opening limiter. Disc stack stress and opening characteristics vs. applied pressure may be determined with simplified analytically derived model and full 2D model including almost all significant forces and moments in a stack of circular plates. An advantage of a simplified disc stack model is possibility of its implementation in an environment supporting matrix operations, e.g. Matlab. Practical implications: A valve system has to withstand the cyclic pressure load across the piston. The number of discs, their diameters and thicknesses directly affect durability of a valve system. Damper force and valve durability expressed in life-cycles are the optimization criteria considering during selection and tuning of a valve system. Originality/value: A new valve system was developed in two versions, i.e. simplified and advanced. The model allows durability prediction at the design stage reducing the testing costs of low-performance valve systems.