Wyniki wyszukiwania - BazTech

1

Thermal effect on the dynamic error of a high-precision worktable

Zou H., Wang B.

Archives of Civil and Mechanical Engineering

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2017

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Vol. 17, no. 2

336--343

EN

This paper investigates the thermal effect on the dynamic error of a high-precision machine worktable during operation. The thermo-mechanical model was established to obtain the motion errors of the worktable by considering the combined effects of varying internal heat sources and external thermal drifts. The temperature tests were performed to obtain the initial conditions of the model and provide a verification for the analytical convection coefficients and heat flux, which were obtained by inverse analysis. The predicted yawing errors of the worktable were confirmed by interferometer tests. Numerical and experimental results suggest that the environmental temperature fluctuation is the largest contributor to the motion errors of the worktable, and they increase with the increasing of environmental temperature. This study allows deeper insights into the underlying mechanisms that result in the motion accuracy variations of the worktable due to the thermal effects, which can provide a strategy for manufacture to further compensate the thermal error and realize ultra precision.

2

Analysis of mechanical effects of low- and high-frequency temperature changes in a massive concrete dam

Urbański A., Opyrchal L.

Czasopismo Techniczne. Środowisko

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2015

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Y. 112, iss. 2-Ś

187--198

EN

The numerical simulation of time evolution of thermal and mechanical fields in a selected section of a massive concrete dam was undertaken by means of the Finite Element Method (FEM) using 3D modelling. Low- (i.e. with time period – year) and high frequency (i.e. with time period – day) cycles of environment temperature variation were considered. The results of the computation confirmed the hypothesis of the vulnerability of the structure to thermal influences and explained the mechanism of the structural defects observed.

PL

W pracy przedstawiono symulacje numeryczne dotyczące efektów termo-mechanicznych w masywnej zaporze betonowej. Zastosowano trójwymiarowe modelowanie metodą elementów skończonych niestacjonarnego w czasie pola temperatury i pól mechanicznych. Rozpatrzono zarówno wpływ zmian temperatury otoczenia w cyklu rocznym, jak i w cyklu dobowym. Wykazano, że mogą być one przyczyną zaobserwowanych uszkodzeń na powierzchniach betonu.

3

Experimental study of a PA66 solid polymer in the case of cyclic shear loading

Bles G., Gadaj S. P., Nowacki W. K., Tourabi A.

Archives of Mechanics

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2002

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Vol. 54, nr 2

155-174

EN

Experimental mechanical results concerning cyclic shear tests without lateral force and simple shear tests with measurement of temperature, performed on sheet samples of PA66 polyamide, are presented. These tests are performed using special shear devices, attached to a classical tensile testing machine. The aim of our work was the examination of thermomechanical characteristics of solid polyamide during shear loading. This study allowed us to analyse the changes of the stress and strain characteristics, shear modulus, ratcheting, relaxation effects and thermomechanical effects.