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超声捶击提高超细晶粒钢焊接接头的疲劳性能 总被引:7,自引:1,他引:6
焊接接头疲劳强度是其最重要的服役性能,由于焊接残余应力的作用和焊接接头处的几何不连续性,焊接接头的疲劳强度一般大大低于母材,采用超声捶击方法提高超细晶粒钢焊接接头的疲劳强度,通过对对接接头焊践处进行超声波冲击处理,对比超声波冲击处理后焊接接头的疲劳强度,实验结果表明:超声捶击使得S-N曲线右移,FAT(循环寿命为10^6时的疲劳强度)提高幅度达到66%,在应力范围为200MPa的疲劳寿命提高58倍,研究表明,经超声捶击处理,焊趾处的应力集中系数相应减小,焊接残余应力由拉应力转换为压应力,这是超声捶击提高焊接接头疲劳强度的主要机制。 相似文献
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本文研究了45钢不同缺口半径及经预压,喷丸处理后对试样弯曲疲劳裂纹萌生寿命的影响。研究结果表明:随着试样缺口根部半径的增大,试样的弯曲疲劳裂纹萌生寿命增加。 相似文献
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2024铝合金喷丸试件疲劳寿命试验及仿真研究 总被引:2,自引:0,他引:2
现有的喷丸材料疲劳性能研究扩展有限元模型没有考虑残余应力对裂纹扩展的影响。对2024铝合金的喷丸与未喷丸试样进行三弯疲劳试验,以明确喷丸工艺对试件疲劳寿命的强化作用。通过ABAQUS建立试件的二维平面应力模型,导入残余应力并利用扩展有限元法模拟循环载荷下裂纹的萌生与扩展,对比试验结果来验证该扩展有限元数值模型的正确性。最后基于该数值模型,改变载荷工况,研究不同载荷工况下残余应力对疲劳寿命的影响,得到喷丸残余应力强化作用与载荷工况的关系。结果表明:喷丸引入的残余应力可以有效地增强试件的疲劳寿命;过大的循环载荷可能造成喷丸残余应力发生松弛;在最大载荷不变的前提下,应力比越小,试件疲劳寿命越短;应力比越大,残余应力对疲劳寿命强化效果越明显。 相似文献
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激光喷丸强化对半圆孔件疲劳寿命的影响 总被引:2,自引:1,他引:1
为研究激光喷丸强化对7075-T6铝合金半圆孔件疲劳寿命的影响,对激光喷丸与未喷丸的试样进行了对比试验,利用X射线应力仪测定其表面残余应力,并对试样进行疲劳拉伸试验.用扫描电镜观察了两类试样疲劳断口的形貌,并采用数理统计方法对其疲劳寿命进行分析.研究表明:经激光喷丸处理区域,表面存在较大的残余压应力,幅值为310 MPa;未喷丸试样疲劳裂纹条带的宽度为0.7~0.8μm,而喷丸试样疲劳裂纹条带的宽度为0.3~0.4μm,说明喷丸试样裂纹扩展的速度比未喷丸试样慢很多;激光喷丸后半圆孔件的疲劳寿命比未喷丸的疲劳寿命提高了2.8~7.2倍. 相似文献
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为了能够在设计阶段对承受随机载荷作用的焊接结构的焊缝进行疲劳寿命预测,该文以随机振动理论为基础,结合主S-N曲线法,通过推导证明了用于焊接结构疲劳寿命评估的等效结构应力与激励载荷之间存在线性传递关系,从而提出了一个频域的焊接结构随机振动疲劳寿命概率预测新方法。该方法能够解决多随机载荷作用下复杂焊接结构振动疲劳寿命预测问题。通过T型接头的算例对比分析,证明了该方法能够考虑激励载荷的频率对焊缝疲劳寿命的影响。直接以线路实测随机加速度谱做为激励载荷,对某轨道集装箱平车车体结构关键焊缝的振动疲劳寿命进行预测,结果表明:该方法的预测结果与实际情况吻合,便于工程应用。 相似文献
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单个冲击对不锈钢管道焊接头低周疲劳寿命的影响 总被引:2,自引:0,他引:2
完成了单个冲击对1Cr18Ni91不锈钢管道焊接头试样低周疲劳寿命影响的试验研究。单个试验最大瞬时峰值应变率达480s^-1。试样未经消除焊接残余应力。采用成组法试验(每组7个试样),对称加载模式,总应变幅为0.00228。结果表明,冲击影响受到焊接残余应力和冲击塑性导入机制的耦合作用。焊接残余应力与冲击应力叠加将增加材料损伤,而冲击塑性导入将减缓疲劳损伤和降低疲劳寿命分散性。前者扼制后者。考虑疲 相似文献
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M. Liakat M. Naderi M. M. Khonsari O. M. Kabir 《Journal of Nondestructive Evaluation》2014,33(3):309-316
A nondestructive testing method is presented for the prediction of the remaining fatigue life (RFL) of metals with prior fatigue damage subjected to tension-compression fatigue load. It is shown that the slope of temperature rise obtained from a short-time excitation fatigue test is a good candidate to assess the present state of fatigue damage in the material. Three series of uniaxial tension-compression normal fatigue tests are carried out with two different materials under different loading conditions to characterize their fatigue behavior. Eight validation tests are performed under different loading conditions to evaluate the RFL prediction capability of the proposed method. Results show that the proposed method has good potential for predicting RFL of metallic specimens. 相似文献
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Effect of Through-Thickness Stitching on the Fatigue Life of Composite Single-Lap Joints 总被引:1,自引:0,他引:1
An exploratory experimental evaluation has been undertaken to investigate the effect of through-thickness stitching on the fatigue life of composite single lap joints. Balanced single lap joints were considered, and the lay-up for the adherends was (0/±45/90)s Specimens were stitched transversely and through-the-thickness with Kevlar® thread in a zigzag pattern and were manufactured using the resin transfer moulding (RTM) technique. Preliminary experimental results have indicated that stitches remain intact when the crack starts growing from either side of the overlap. This consequently imparts a significant improvement in the fatigue life of stitched versus unstitched counterparts. 相似文献
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Stepanov G. V. Kharchenko V. V. Babutskii A. I. Romanov S. V. Feofentov N. A. Kravchenko I. V. 《Strength of Materials》2004,36(3):321-326
The procedure for calculating the life of header – steam generator connector weld joints is proposed. It allows for running out the material plasticity reserve upon static cyclic elastoplastic loading as well as operating conditions, local stress concentrations, and residual stresses after welding. 相似文献
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采用轴向脉动拉伸疲劳试验,研究了爆炸复合321/Q370qD双金属板对接接头的疲劳性能。通过数理统计计算,获得了50%及97.7%两个置信度下试验材料的S—N曲线方程及据此确定的疲劳强度(2×10~6次),两个置信度下的疲劳强度均高于设计指标。对疲劳试样断口进行了观察,结果显示:疲劳裂纹大都起始于复合板对接接头的基层,个别起始于复层;裂纹稳定扩展区具有明显的疲劳辉纹,瞬断区具有典型的韧窝特征。断裂力学分析表明:疲劳裂纹起始于复合板不同组分的驱动力与复合板对接接头不同组分的循环屈服强度和弹性模量的乘积有关。 相似文献
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V. T. Troshchenko 《Strength of Materials》2000,32(5):427-433
General regularities in the variation of threshold stress intensity factors of metals are considered taking into account the influence of various factors. Justification is offered of the possibility of predicting fatigue limits for smooth specimens and specimens under conditions of fretting from the known characteristics of threshold stress intensity factors. 相似文献