共查询到18条相似文献,搜索用时 78 毫秒
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为了研究船体曲面钢板感应加热过程的加热方式,利用实验和数值模拟的方法,分析了各自加热过程中钢板的温度及变形量的变化规律.针对非持续式感应加热方法,初步给出最佳加热时间参数.利用罗氏线圈测量加热过程中感应器的电流强度和频率,实验结果和数值模拟结果相吻合,验证了数值模拟计算的准确性.结果表明:合理的分配感应加热的时间参数,选择非持续式感应加热可以达到预期的成型效果,在提高加热效率的同时有效的节约了加热能源. 相似文献
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通过感应加热实现板材的热弯成形,具有精准控制、安全便捷等特点。本研究采用新型便携式感应加热设备,对8mm船板钢进行热弯成形试验;并基于热-弹-塑性及弹性有限元计算,预测感应加热面外弯曲变形,与测量数据基本吻合。同时,考虑试验成本高昂,通过大通量的有限性计算,建立感应加热参数与板材弯曲的数据库;并通过回归分析,拟合出感应线圈移动速度与板材弯曲角度间的数学关系。当板材弯曲曲率相同时,通过线加热位置的迭代二分法,可线性逼近板材的目标弯曲形状,进而快速规划加工工艺,并进行了验证。 相似文献
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吊耳局部有限元建模技术分析 总被引:2,自引:0,他引:2
文章中提出了几肿简化处理方法来模拟插销与吊耳的接触.通过有限元计算结果比较,发现提出的简化处理方法与接触算法计算结果接近,且耗时少、操作简单,可以将这些简化处理方法广泛应用于吊耳的有限元强度校核. 相似文献
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In this paper, the ultimate strength of unstiffened steel plates under uniaxial in-plane compression is numerically studied considering the local lateral impact of a rigid-body impactor. The plates are made of mild steel, where its behaviour is modelled by using the Johnson-Cook material model. The material parameters of the Johnson-Cook material model calibrated by the authors were employed for predicting the behaviour of the target in order to numerically reproduce the impact tests. The value of average in-plane stress of the plates is determined accounting for the collision of rigid-body impactor with masses of 50–150 gr and velocities of 400–1200 m/s. Moreover, the effects of stress waves induced as a result of lateral impact of the rigid-body impactor on the ultimate strength of the plates under uniaxial in-plane compression are also assessed. The results indicate that the ultimate strength of the plate decreases due to stress-wave creation and thus, it is required to take that into account. Besides, it is revealed that assuming the final damaged state of the plate after being laterally impacted by the rigid-body impactor as an initial condition, does not yield a correct response when evaluating its ultimate compressive strength under uniaxial in-plane compression. 相似文献
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不同冷却方式对大尺寸钢板感应加热成形的影响 总被引:1,自引:1,他引:0
为有效解决船用中厚钢板复杂曲面加工问题,本文探究了空气冷却、正面水冷和反面水冷方式对大尺寸钢板弯曲成型的影响因素。首先采用COMSOL Multiphysics仿真平台模拟了电磁感应加热和冷却变形多物理场同步耦合过程,然后分析了各种因素对大尺寸钢板弯曲成型影响,最后通过实验验证了有限元模型的可靠性,并对感应加热弯曲成型效果进行评估。研究结果表明:(1)相对于水冷,空冷对钢板Y向位移改变效果显著。(2)相对于空冷,水冷对钢板角位移的改变影响明显。(3)当频率为50kHz时,电流频率对表面温度和角位移影响显著。(4)当钢板长宽比≥1:2时,Y向位移的增加比较显著;当长宽比≈1:1时,角位移的改变比较明显。 相似文献
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Civil infrastructure systems such as bridge piers, navigational guide walls, and protection structures that are located near navigable waterways are inherently at risk for being impacted by cargo vessels such as barges and ships. To safely design such systems to possess adequate vessel impact resistance, structural loads associated with potential vessel-structure collision conditions must be quantified in a conservative manner. While high-resolution finite element impact simulations may be employed to compute such loads, care must be exercised in defining the material characteristics of the vessel if conservative structural design loads are to be obtained. Importantly, constitutive relationships assigned to steel components in the vessel model must be capable of accounting for strain rate sensitivities and large-scale plastic deformations.In the present study, strain rate sensitive constitutive models were developed for two types of steel commonly utilized in marine construction in the United States—ASTM A36 and ASTM A1011. Tension tests were conducted over a wide range of strain rates (7.00 × 10−5 s−1 – 250 s−1) spanning from quasi-static to intermediate and high rates that are typically associated with vessel-structure impact events. A novel testing apparatus—employing an impact pendulum as an energy supply mechanism—was designed for this study to conduct intermediate to high-rate material testing. Features of the apparatus, discussed in this paper, overcome key problems encountered in other studies that have employed impact loading for tensile material testing. From the testing program, representative stress–strain relations and Cowper–Symonds strain rate sensitivity parameters were developed for the materials tested. Rate sensitivities of the two steel grades tested were found to be very similar to each other. Additionally, rate sensitivities from the present study agreed well with ultimate stress data measured in past studies of mild steel, but were found to be less rate-sensitive than yield stress data measured in past studies. 相似文献
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This paper presents a practical procedure for creating finite element (FE) model for vibration analysis of cruise ships. The most preferable FE modelling approaches are studied and discussed through case studies of common ship structures, which cover the range from low to high frequencies. The application of homogenized equivalent single layer (ESL) theory based equivalent element for stiffened panel is extended to local forced vibration analysis, where inertia induced interaction between plate and stiffener occurs. Modal method is used with an energy-based correction for accounting the plate-stiffener interaction into modal properties. Case study results reveal that mesh density of one 4-node element per web frame spacing is suitable for global FE-model when vibration analysis is limited to global hull girder modes. For such modes it is sufficient to only include the membrane stiffness of stiffened panels. For investigating the response at higher frequencies, bending properties of stiffened panel should be included and mesh density should be at least two elements per web frame spacing. Then forced vibration analysis can be performed with an excellent accuracy up to frequencies about one third of the local plate natural frequencies between the stiffeners. Beyond that, the influence of the local plate vibration becomes more significant in panel vibration, making the ESL-theory based element limited. With the applied correction method, the validity of the ESL-model can be extended to approximately two thirds of the local plate natural frequency. 相似文献
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上层建筑振动是影响船舶整体稳定性的主要因素,所以对其进行有效分析具有重要的现实意义。本次针对以往基于经验公式建立软件程序来计算上层建筑振动频率,存在精度不足的问题,提出一种有限元分析方法。利用有限元分析法进行船舶上层建筑振动性能研究主要分为两部分:先是选定船舶参数,利用利用Ansys软件进行上层结构有限元建模;后是对该模型进行求解,计算船舶上层建筑振动频率,实现振动性能研究,并与基于经验公式软件程序法进行对比,得出有限元分析法精度更高,结果更接近真实值。 相似文献