Papers by Keyword: Varying Load

Abstract: This paper proposed an approach for a control, which fuzzy logic method was designed and used in the refrigeration system based on the summary of the common control methods on electronic expansion valve (EEV) and variable speed compressor(VSC). The experiment had been carried out, that showed the fuzzy logic controller achieve more stable superheat and water temperature values against to a disturbance and had good energy saving potential.

Abstract: It is frequently reported by customers that the lower-left and lower-right wheels in the load fork mechanism of a kind of forward-type stacker designed based on static strength analysis are abraded faster than expected. In this paper, we studied by means of kinetics analysis and simulations the forces applied on parts of the fork mechanism. The simulation results show that the maximum values of instantaneous forces during operations are much higher than those derived based static force analysis, and thus explained the reason of the above-mentioned abnormal abrasion. The results also mean that static force analysis is not suitable for part strength design. Instead, one shall adopt kinetics analysis to explore the instantaneous forces in design.

Abstract: Although fatigue limit diagram is defined in principle for constant stress amplitude condition, it is often considered that fatigue failure would not occur even in varying loading if applied stresses were kept within the fatigue limit diagram. However, it was shown in the case of small-notched specimen and fretting fatigue that fatigue failure occurred in some special case of variable amplitude loading condition even when all stress amplitudes were kept within the fatigue limit diagram. The cause of this phenomenon was examined using two-step and repeated two-step stress patterns in which the first step stress was with zero mean stress and the second step stress had a high mean stress. A non-propagating crack was formed by the first step stress. This crack functioned as a pre-crack for the second step stress with high mean stress. Consequently, fatigue failure occurred even when all stress amplitudes were kept within the fatigue limit diagram. It was an unexpected fracture caused by the interference effect of non-propagating crack and mean stress change.