Shakedown limit of rail surfaces including material hardening and thermal stresses
01 Oct 2003-Fatigue & Fracture of Engineering Materials & Structures (Blackwell Science Ltd)-Vol. 26, Iss: 10, pp 985-998
TL;DR: In this paper, the authors show that the kind of hardening observed for rail steel has a considerable influence on the shakedown limit and the residual stresses provide the structure to shake down to pure elastic behaviour in subsequent load cycles up to a shakedown.
Abstract: Sliding friction between railway wheels and rails results in elevated contact temperatures and gives rise to severe thermal stresses at the wheel and rail surfaces. The thermal stresses have to be superimposed on the mechanical contact stresses. Due to the distribution of stresses, the rail surface is generally subjected to higher stresses than the wheel surface. The elastic limit is reduced and yield begins at lower mechanical loads. During the first cycles of plastic deformation, the material hardens and residual stresses build up. The residual stresses provide the structure to shake down to pure elastic behaviour in subsequent load cycles up to a shakedown limit. The kind of hardening observed for rail steel has a considerable influence on the shakedown limit. The shakedown limit is dropped to lower mechanical loads due to the thermal stresses in the rail surface as well. This might cause structural changes in the rail material and rail damage.
TL;DR: In this article, the effect of decarburisation on rolling contact fatigue and wear was investigated under water-lubricated rolling/sliding contact, and it was found that the wear rate of the rail disc increased while that of the wheel disc decreased.
TL;DR: In this paper, a finite element method (FEM) was used to study thermal-elastic-plastic deformation and residual stress after wheel sliding on a rail, where the consideration of sliding contact between the wheel and the rail was restricted to a two dimensional contact problem.
TL;DR: In this paper, the effects of friction coefficient and slip/roll ratio on the wear rate and rolling contact fatigue are investigated, and frictional heating effects have been found to increase the rate of damage accumulation by ratcheting, leading to increased wear and tendency for rolling contact fatigues.
TL;DR: In this paper, a coupled thermomechanical modeling procedure for the wheel-rail contact problem was presented and the flash-temperature and stress-strain responses when thermal effects are present.
TL;DR: In this paper, a multi-step FE modeling strategy has been proposed to predict the temperature evolution, thermo-mechanical response, surface fatigue life and wear behaviors in railway rail for multi wheel passages.
01 Jan 1985
TL;DR: In this article, an Armstrong-Frederick type hardening rule utilizing the concept of a limiting surface for the backstresses was proposed to predict long-term ratchetting rate decay as well as constant ratcheting rate for both proportional and nonproportional loadings.
Abstract: The existing plasticity models recognize that ratchetting direction strongly depends on the loading path, the stress amplitude, and the mean stresses, but their predictions deviate from experiments for a number of materials. We propose an Armstrong-Frederick type hardening rule utilizing the concept of a limiting surface for the backstresses. The model predicts long-term ratchetting rate decay as well as constant ratchetting rate for both proportional and nonproportional loadings. To represent the transient behavior, the model encompasses a memory surface in the deviatoric stress space which recalls the maximum stress level of the prior loading history. The coefficients in the hardening rule, varying as a function of the accumulated plastic strain, serve to represent the cyclic hardening or softening. The stress level effect on ratchetting and non-Masing behavior are realized with the size of the introduced memory surface. Simulations with the model checked favorably with nonproportional multiaxial experiments which are outlined in Part 2 of this paper.
••01 Jun 1963
TL;DR: When two metal cylinders roll together under a contact pressure sufficient to cause yielding, a surprising mode of plastic deformation occurs as mentioned in this paper, where the surface of each cylinder is progressively displace, and the deformation can be accelerated by the contact pressure.
Abstract: When two metal cylinders roll together under a contact pressure sufficient to cause yielding, a surprising mode of plastic deformation occurs. The surface of each cylinder is progressively displace...
TL;DR: In this paper, the Laplace transforms and the method of Green's functions were used to analyze the contact temperatures and temperature fields of components in relative sliding motion, and it was shown that each kind of fluctuation causes a rise of the maximum contact temperature.
TL;DR: In this article, the authors reviewed various ways of improving the constitutive models for the description of both monotonic and cyclic rate-independent plasticity and the correct modeling of ratchetting effets.
Abstract: In the first part, some classical experimental results are briefly recalled. The second part reviews various ways of improving the constitutive models for the description of both monotonic and cyclic rate-independent plasticity and the correct modeling of ratchetting effets. In particular, it is shown that simple modifications of the dynamic recovery terms in the kinematic hardening rules offer the possibility of large improvements. Two specific models are then considered in detail, showing the great similarities in their mathematical structure and their numerical responses for uniaxial and multiaxial ratcheting conditions
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