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In this paper the tower base shear forces and bending moments of a shallow water offshore wind turbine have been rigorously calculated by using a nonlinear simulation method taking into account the bottom effects. It has been found that nonlinearly simulated realistic waves with bottom effects should be used as inputs in the stochastic time domain simulation in order to design an un-conservative support structure for the offshore wind turbine. In order to further improve the simulation efficiency, a transformed linear simulation method has been utilized in this paper for generating equivalent waves as those obtained from the nonlinear simulation method. The accuracy and efficiency of the transformed linear simulation method have been convincingly substantiated through the subsequent calculation examples in this article. 相似文献
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Flexible pipes are key equipment for offshore oil and gas production systems, conveying fluids between the platform and subsea wells. The structural arrangement of unbonded flexible pipes is quite complex, encompassing several layers with polymeric, metallic and textile materials. Different topologies and a large amount of intricate nonlinear contact interactions between and within their components, especially because of the relative stick-slip mechanism during bending, makes numerical analysis challenging. This paper presents an alternative three-dimensional nonlinear finite element model that describes the response of flexible pipes subjected to combined axisymmetric and bending loads. To simulate the response of a flexible pipe under axial tension or compression combined with uniform curvature, an equivalent thermal loading is employed on the external sheath, which is modelled as an orthotropic thermal expansion material with temperature-independent mechanical properties. To assess the feasibility of the proposed model, the bending moment versus curvature of the finite element solution is compared with experimental results obtained in literature and good agreements are found between them. Detailed finite element results such as contact pressures, armour wire slip displacements and friction, normal and transverse bending stresses are also shown and compared with available analytical models. 相似文献
105.
In this previous study, a consistent theoretical formula was established in single hull structure, taking account of all the structural components affecting the load share of each member, in combination with the combined load effect of direct force from the longitudinal stiffener and shear force on the primary supporting member. What's more, it has been known qualitatively that the bending moment at the root of the web stiffener in double hull structure is less than that in single hull structure. However, the difference between double hull and single hull structures has not been achieved. In this study, the authors develop a theoretical formulation to represent the stresses at the root of the web stiffener due to the load from both the longitudinal stiffener and the shear force on the primary supporting member in the double hull structure. Then, the results calculated by the derived formulae are compared with the results obtained by finite element analysis, and good accuracy of the proposed formula was verified. Finally, the calculated stresses were compared between double hull and single hull structures. On one hand, the share of loading born by the web stiffener is almost comparable between the double hull and single hull structures. On the other hand, the bending moment at the root of the web stiffener is smaller in the double hull structure than in single hull structure, and therefore, the maximum stress is smaller. 相似文献
106.
基于混合设计的高性能钢梁抗弯性能及延性试验 总被引:1,自引:0,他引:1
基于混合设计的理念,采用中国产高性能钢HPS 485W和普通结构钢Q235,加工制造了6片混合设计工字形钢梁,在跨中单点加载,研究试验梁的抗弯承载能力、变形特征及最终的破坏形态。试验结果表明:腹板屈曲强度和试验梁侧向支撑刚度对试验梁的极限承载力、延性和失效形式有显著影响;试验梁的抗弯承载力主要由翼缘提供,但抗弯延性主要受腹板控制,承载力下降阶段受腹板屈曲强度影响显著;采用厚实截面设计的高性能钢梁可以达到全截面塑性,在有效的侧向限位下高性能钢梁具有很好的延性。试验结果与理论计算结果的对比表明,塑性弯矩理论计算结果与试验值吻合较好。 相似文献
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减震器弹簧的疲劳强度受材料表面的裂纹、疵点、伤痕及腐蚀介质、工作温度等影响很大,弹簧疲劳强度偏低不能满足弹簧最大工作负荷下疲劳强度的要求,会造成减震器弹簧弯曲、变形,甚至断裂。 相似文献
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曹传江 《内蒙古公路与运输》2014,(3):45-47
通过试验,分析了抗车辙剂掺量对沥青软化点、针入度、低温延度和峰值拉力的影响,并对比同一抗车辙剂掺量上下层沥青各指标间的差异。试验结果表明:同一层沥青,随着抗车辙剂掺量的增大,软化点和峰值拉力逐渐增大,而针入度和低温延度逐渐减小;当抗车辙剂掺量相同时,上层沥青的软化点和峰值拉力大于下层沥青,针入度和低温延度小于下层沥青;抗车辙剂掺量越大,上下层沥青各指标差距越明显,沥青越容易发生离析。 相似文献
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结合工程实例,阐述钢纤维混凝土在大管桩中的应用。实践证明,掺入钢纤维,可以提高大管桩结构混凝土的延展性,减少锤击大管桩结构的脆性破坏。而且具有良好的抗腐蚀性能,从而延长大管桩的使用寿命,有推广应用的价值。 相似文献