共查询到18条相似文献,搜索用时 140 毫秒
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论钢轨残余应力的测定方法 总被引:1,自引:0,他引:1
本文叙述了钢轨残余应力研究的重要性,介绍了目前测定钢轨残余应力的几种方法,阐述了它们各自的优缺点,同时对今后准确,迅速测定残余应力的技术发展方向提出了建议. 相似文献
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An Experimental Investigation into Additive Manufacturing-Induced Residual Stresses in 316L Stainless Steel 总被引:1,自引:0,他引:1
Amanda S. Wu Donald W. Brown Mukul Kumar Gilbert F. Gallegos Wayne E. King 《Metallurgical and Materials Transactions A》2014,45(13):6260-6270
Additive manufacturing (AM) technology provides unique opportunities for producing net-shape geometries at the macroscale through microscale processing. This level of control presents inherent trade-offs necessitating the establishment of quality controls aimed at minimizing undesirable properties, such as porosity and residual stresses. Here, we perform a parametric study into the effects of laser scanning pattern, power, speed, and build direction in powder bed fusion AM on residual stress. In an effort to better understand the factors influencing macroscale residual stresses, a destructive surface residual stress measurement technique (digital image correlation in conjunction with build plate removal and sectioning) has been coupled with a nondestructive volumetric evaluation method (i.e., neutron diffraction). Good agreement between the two measurement techniques is observed. Furthermore, a reduction in residual stress is obtained by decreasing scan island size, increasing island to wall rotation to 45 deg, and increasing applied energy per unit length (laser power/speed). Neutron diffraction measurements reveal that, while in-plane residual stresses are affected by scan island rotation, axial residual stresses are unchanged. We attribute this in-plane behavior to misalignment between the greatest thermal stresses (scan direction) and largest part dimension. 相似文献
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《粉末冶金学》2013,56(4):278-284
AbstractIn this study, finite element method and X-ray diffraction measurement were used to determine the thermal stress distribution of functionally graded WC–Co composites. The calculated results show that high stress concentration occurs in the cobalt gradient zone, tensile stress pile-up occurs in the cobalt rich zone and compressive stress pile-up occurs in the surface zone. As the sintering time is increased, compressive residual stress in the surface zone has a tendency of decreasing. The maximum value of compressive stress in the surface zone is 250 MPa. The results are in good agreement with X-ray diffraction measurement results. For the purpose of this work, the material design method is achieved by changing the calculated parameters. 相似文献
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利用盲孔法、X-Ray法、中子衍射法和超声法对Q390高强抗震板及U形弯曲件进行残余应力检测,并对这4种方法测试得到的应力结果进行分析研究。结果表明,以上4种检测方法均要考虑其特定的检测应用范围,X-Ray法针对钢板表面下微米级深度的微米级晶格尺度范围局部点应力进行检测,中子衍射法可在毫米级尺度局部区域进行应力检测,盲孔法反映的是因毫米尺度钻孔导致的钢板表面孔周边的应力变化,超声法则可以通过连续扫描检测整个钢板残余应力的宏观分布变化。因此,对于工业钢板,超声法测试残余应力更加科学、合理、准确。同时,通过U形试样建立稳定的应力应变场,利用超声设备使用不同参考态对Q390高强抗震板弯曲件及退火弯曲件进行测试,结果表明,测试参考态的选取对应力测试结果影响很大,材料各向异性的影响对应力测试结果不可忽视。 相似文献
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为从力学本质上揭示SI-FLAT非接触式板形仪的检测原理,基于薄板流固耦合振动理论,建立了薄板振幅与残余应力关系的数学模型.在非协调Föppl-von Kármán方程组的平衡方程中引入惯性项与流体压强项,利用气动载荷在时间上的周期性将流体速度函数、流体压强函数、薄板挠度函数和薄板应力势函数的时间变量分离出来,得到描述SI-FLAT板形仪稳定工作状态的偏微分方程组.进一步利用分离变量法求解该方程组,最终建立起薄板振幅与残余应力的数学关系.同时结合实测残余应力数据,利用Siemens提出的振幅-残余应力模型反算得到实际薄板振幅分布,并将其与流固耦合振动模型计算的振幅进行对比,验证了提出的数学模型的可靠性.进一步利用流固耦合振动模型分析了气泵进风口流体速度、检测距离和激振频率对振幅的影响,为SI-FLAT板形仪科学合理的利用提供了理论依据. 相似文献
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用TRS-80微机—D/MaX-3A衍射仪联机系统及峰位检测程序,建立了自动测定材料残余应力的实验方法。 相似文献
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预热对铍环激光束钎焊过程的影响研究 总被引:1,自引:0,他引:1
研究预热对铍环激光束钎焊过程温度场和应力场分布的影响。采用轴对称模型和热力解耦的有限元方法,并假定沉积到钎缝表面的激光束能量为Gauss分布,预热通过在焊接加热前添加一个能量密度低、有效加热半径大的单独工况实现。结果表明,预热使镀环钎缝外表面焊接最高温度增加,温度梯度减小,但焊深明显增加;采用预热工况焊接后,钎缝附近塑性变形区焊接残余应力明显减小,而热影响区残余应力增大。从整体分布来看,预热使铍环外表面焊接残余应力分布均匀化。对铍环外表面钎缝附近焊接残余应力进行X射线应力测试,并与有限元分析结果对比,二者应力变化趋势基本一致。 相似文献