The objective of this work was to study the fatigue and post-fatigue monotonic behaviour of partially prestressed concrete (PPC) beams with a high degree of prestress. Eleven large PPC beams were tested under fatigue and monotonic loading. The effects of applied load level and severity of fatigue damage on the beams' fatigue and post-fatigue monotonic behaviour were studied and analysed. The results indicated that the fatigue behaviour of beams with a high degree of prestress was dependent on the applied load level. For an optimum and safe design, the applied load level should be less than 1·28 times the cracking load, the maximum crack width should be limited to 0·20 mm and the initial maximum stress range of non-prestressed reinforcing bars before repeated loading should be less than 170 MPa. The post-fatigue monotonic behaviour of beams was related to the severity of fatigue damage prior to the monotonic test. Low fatigue damage was found to have only a slight impact on the monotonic behaviour of the beams, whereas medium and high fatigue damage respectively reduced the ultimate strength by up to 15·2% and 18·0% and increased the deformability ductility index by up to 18·6% and 41·0%.
The material of pillow has influenced on body pressure distribution and human comfort. This paper studied the relationship between the characteristic of pillow materials and sleeping comfort in supine position through head, neck, back pressure distribution system and subjective evaluation on ergonomics methods. This paper selected chemical fiber, buckwheat, latex, memory foam, inflatable cushion, traditional Chinese medicine / tea and pearl cotton for experimental materials. The results showed that the pillows with memory foam and latex was better in pressure distribution and subjective evaluation. The pillow with traditional Chinese medicine / tea and inflatable cushion had lower elasticity and poorer sleeping comfort. The buckwheat pillow can relieve neck fatigue. This study results have important reference value to the material of pillow and comfort pillow design.
In this paper, Based on the research of CFD basic theory and several key technologies, the numerical model for solving three-dimensional flow field around the open water rudder is proposed. And with the help of computing platform FLUENT, several kinds of numerical simulation of maneuverable movement of NACA0015 rudder have been done. The numerical results are compared with experimental results, showing that the CFD model which is proposed in this paper is suitable for computation of hydrodynamic forces and simulation of the viscous flow around the open water rudder.
The resilience of mattress foam has influenced on body pressure distribution characteristic of mattress and human comfort. This paper dealt with resilience of foam and body pressure distribution through resilience test instrument for mattress foam and body pressure distribution system. The results showed that the resilience of latex foam was better and the body pressure distribution of mattress with latex foam layer was better. This study results have important reference value to the flexibility of mattress and comfort design.
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