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双语推荐：压应力

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利用有限元分析了材料在压痕过程中各变量,并计算了硬度HRC值,与在硬度试验中所测HRC值吻合,证实了有限元分析的正确性;在此基础上,分析了试件具有残余应力时的压入响应问题,研究了残余应力对圆锥压入响应的影响,探讨了压痕法测试残余应力所存在的问题。研究结果表明:残余拉、压应力以不同程度影响压入响应,压应力使圆锥压头处出现隆起量,而拉应力使其出现下沉量,该表现用于直观法预测残余应力;拉应力使压痕处塑性区域增加,压应力使塑性区域减少,在压痕法测量残余应力时,由于塑性区域事先的未知性而影响应变测试位置的确定,从而影响测量残余应力的准确性。
The finite element method is used to study indentation parameters under load, and calculate hardness. The calculated values agree well with the measurements, indicating effectiveness and reliability of the finite element analysis. Based on numerical simulation of a cone indenter, we analyze the indentation response of materials with varying residual stress, and the effect of residual stress on the indentation response. The problem arising from indentation for measuring residual stress is studied for the plastic region around indentation. The result shows that the residual stress affects indentation response in different degrees. Pile-up appears around the cone indenter due to compression stress, and sink-in appears due to tensile stress. These can be used to determine the residual stress by direct observation. Plastic region is clearly widened with tensile stress and narrowed with compression stress. The position for strain becomes uncertain in the indentation test due to unknown plast

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为了研究SS400钢板不同焊接方法残余应力的分布规律，分别对4 mm厚的低合金高强钢采用手工电弧焊和氩弧焊进行焊接，焊接后采用盲孔法测量钢板的残余应力，得到了残余应力的分布曲线。试验结果表明：手工电弧焊在焊接区垂直焊接方向的残余应力最大值为387 MPa，在焊缝两侧为压应力，距离焊缝两侧12 mm处，压应力最大；平行焊接方向上的残余应力在中间位置为拉应力，在工件两边为压应力，靠近边缘压应力增大。氩弧焊垂直于焊接方向上的最大拉应力为328 MPa，在焊缝两侧的距离为7 mm处，压应力最大；平行于焊接方向上的残余应力曲线与手工电弧焊的相似，氩弧焊的焊接变形小于手工电弧焊。
In order to study the distribution rule of SS400 sheet under different welding residual stress, manual electric arc welding and argon arc welding method were used to weld 4 mm low alloy high strength steel. The residual stress of steel plate after welding was measured by the blind hole method, and the distribution curve of residual stress was obtained. The experimental results showed that: for manual electric arc welding the maximum value of residual stress in welding zone vertical direction is 387 MPa, the residual stress is compressive stress beside weld both sides, the compressive stress value is the maximum in the distance of 12 mm from weld both sides. The residual stress is tensile stress in center position in parallel welding direction;it is compressive stress beside both sides of weldments, and the compressive stress increases close to edge. For argon arc welding, the maximum value of tensile stress in vertical direction is 328 MPa, the compressive stress value is the

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采用两种冲击方式对AISI202不锈钢焊接接头表面进行激光冲击强化处理，利用X射线应力仪测试了激光冲击强化处理后焊接接头的残余应力，研究了单面和双面激光冲击对残余应力分布的影响，分析了残余压应力的形成机理。结果表明，双面激光冲击强化处理效果明显优于单面冲击方式，双面冲击方式能够使试样正反面都获得很大的残余压应力，并且反面的残余压应力水平高于正面，同时使得正反两面残余压应力分布趋于均匀。
The surface of AISI202 stainless steel welding joint was processed by laser shock processing ( LSP) with two different methods. Residual stress of AISI202 welding joint treated by LSP was measured with X-ray stress tester.The effect of one-side and double-side LSP on the distribution of residual stress was investigated, and the generation mechanism of residual compressive stress was analyzed.The results show that the strengthening effect of double-side LSP is better than that of one-side LSP, both positive and negative sides are obtained large residual compressive stress after double-side LSP, and the negative residual compressive stress level is higher than that of the positive''s, and the residual stress distribution of double sides becomes homogeneous.

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采用变流压定围压试验方式,在高温、高压条件下模拟了气藏开发过程,研究了复杂火山岩气藏储层渗透率应力敏感性,对比了变流压定围压与常规的定流压变围压方式评价储层应力敏感性的异同。试验结果表明,火山岩储层渗透率随着孔隙压力的减小而减小,渗透率减小主要发生在孔隙压力从40 MPa下降至25 MPa的变化区间,渗透率损失率与其初始渗透率之间的相关性较差,这与常规沉积砂岩储层具有一定的差别。变流压定围压试验评价的应力敏感性强于定流压变围压评价结果,气藏储层有效应力变化范围内两种试验评价的应力敏感性结果差异更大。基于渗流力学理论,推导得到考虑应力敏感性的气井产能方程。计算结果表明,考虑应力敏感性时气井无阻流量约为不考虑应力敏感性时的63.28%,应力敏感性对气井产能的影响随着生产压差的增大而增大。
Permeability-stress sensitivity of complex volcanic reservoir has been studied using the variable pore pressure-constant confining pressure method. Meanwhile, permeability stress-sensitivity obtained from two different experimental methods also has been compared. The experimental results indicate that the volcanic reservoir permeability declines with the decrease of reservoir pore pressure. Decrease of reservoir permeability mainly occurs in the pore pressure from 40 MPa to 25 MPa. There is no good relationship between rock initial permeability and its loss rate, which is different from that of the sedimentary sandstone reservoir. Permeability-stress sensitivity of tight volcanic gas reservoir obtained from variable pore pressure-constant confining pressure is much stronger than that obtained from constant pore pressure-variable confining pressure. And this difference becomes larger during the actual gas reservoir effective stress range. The gas well productivity equation has been math

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针对压裂作业井中水泥环的力学破坏问题,研究利用膨胀水泥来预防该类破坏。利用有限元方法计算了压裂作业时普通水泥环中的最大主应力,并结合水泥环的力学性能分析了其破坏方式,将膨胀应力与最大主应力叠加后得出了膨胀水泥环中的最大主应力,分析了膨胀水泥预防水泥环力学破坏的原理,评价了膨胀应力对套管受力状况的影响。通过室内实验研究了模拟压裂作业时普通水泥环和膨胀水泥环的破坏情况。研究结果表明,压裂作业时普通水泥环的破坏方式为切向拉伸破坏;膨胀水泥产生的膨胀应力可以降低水泥环中的切向拉应力甚至使其转变为压应力,从而可以预防水泥环的力学破坏;膨胀应力会降低压裂作业时套管中的米塞斯应力,不会导致套管的受力情况恶化。实验结果表明,相同模拟压裂条件下,膨胀水泥环未发生破坏,普通水泥环因切向拉伸应力的作用而破坏,验证了使用膨胀水泥预防压裂井水泥环力学破坏的有效性。
According to mechanical failure of cement sheath in fracturing operations, expanding cement was studied to prevent such failures. The maximum principal stress in common cement sheath during fracturing jobs was calculated using the finite element method, and its failure mode was analyzed with the mechanical performance of cement sheath, then the maximum principal stress in expanding cement sheath was obtained after superimposition of expanding stress with maximum principal stress; the principle of preventing me-chanical failure of cement sheath with expanding cement was analyzed, and the effect of expanding stress on forces on casing was evalu-ated. Through indoor experiments, the failures of ordinary cement sheath and expanding cement sheath in simulated fracturing jobs were studied. The theoretical study results show that the failure mode of ordinary cement sheath during fracturing jobs is tangential tensile failure. The expanding stress produced by expanding cement can reduce the tan

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为了更加准确地确定超应变度，基于米赛斯（ Mises）屈服准则，建立了外压圆筒应力方程。在此基础上，按卸载定理分别建立了受外压与受内压圆筒自增强方程，通过对当量应力求解，获得在弹性阶段与塑性阶段产生屈服的规律，并与按屈雷斯加（ Tresca）屈服条件导出的方程进行了比较。研究表明，外压圆筒的弹性及塑性应力方程与受内压圆筒状态时方程不同，自增强处理后的残余应力大小也有差异，而且按米赛斯屈服准则的残余应力分量比按屈雷斯加屈服条件的残余应力分量大。但由于内外压圆筒的残余应力的当量应力形式是一样的，所以两个强度理论导出的结果在许多地方相同。
In order to accurately determine the value of super strain,the strain equation of pressure cylinders was established on the basis of Mises yield criterion.Based on this,the equation on autofrettage of external pressure cylinders and internal pressure cylinders was built by offloading theorem,the yield rule in the plastic stage and the elastic phase was obtained through solving equivalent stress, and comparison between the results based on Mises and Tresca yield criterion was made.Results show that the elastic and the plastic stresses of the external pressure cylinders are different from equation of the internal pressure cylinders and their residual stresses after removing au-tofrettage pressure also differ from each other.The components of the residual stresses based on Mises yield criteri-on are greater than those based on Tresca yield criterion.But the equivalent stress expression of residual stresses of the external pressure cylinders is the same as the internal pressure c

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针对轧制过程非稳态及润滑特性,通过流体力学分析,建立稳态、非稳态轧制变形区油膜厚度分布模型,提出油膜波动系数以研究油膜厚度的绝对波动,应用卡尔曼微分方程分析了稳态、非稳态轧制界面应力分布,并以稳态应力分布为基础提出应力波动系数以研究变形区应力的绝对波动.结果表明:稳态下压下率增加,轧制界面油膜变薄,压应力、切应力均增加;非稳态下随着入口板带厚度等扰动因素的波动加剧,油膜波动系数变大,绝对波动加剧;不同时刻非稳态压应力波峰的位置和数值都会发生变化;相比于切应力,油膜波动对压应力的影响比较大,当油膜厚度发生6.33%的绝对波动时,压应力和切应力分别产生1.17%和0.24%的绝对波动.
Based on the lubricating and unsteady properties of rolling processes and hydrodynamic analysis, a film distribution model of the deformation zone which concerns the steady and unsteady conditions is set up and the film wave coefficient is proposed which is used to study the absolute fluctuation of unsteady film thickness. The von Karman equation is used to describe the stress distri-bution of rolling interfaces under the steady and unsteady conditions. According to the stress distribution under the steady condition, the stress wave coefficient is proposed which is used to study and describe the absolute fluctuation of unsteady stress. It is found that large reduction results in a thinner film thickness and a larger hydrodynamic pressure and shear stress in the deformation zone under the steady condition. Under the unsteady condition, as the fluctuation of disturbance factors such as inlet strip thickness intensifies, the film wave coefficient increases, indicating that the absolute fl

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试验设计了混凝土压应力和弯曲应力加载装置，利用弹簧变形储能提供持续稳定应力，研究了应力作用下混凝土电通量的变化规律。结果表明，混凝土强度等级越低，渗透性越大，混凝土自身密实程度及裂缝决定其渗透性大小。在压应力作用下，当应力比小于0.4时，电通量随应力比的增大而减小，而应力比大于0.4时，电通量则随应力比增大而快速增大。弯曲应力作用下，电通量随应力比的增大而不断增大。
Experimental designed a loading device for concrete under compressive load and bending load ,using the spring deformation energy storage to provide a steady load force,studied the electric flux change rule of concrete under the action of stress.The results show that the concrete strength grade is lower,the greater the permeability,dense degree of concrete itself and crack size to determine the perme-ability.Under the effect of compressive stress,when the stress ratio is less than 0.4,the electric flux decreases with increasing of stress ra-tio,and stress ratio greater than 0.4,the electric flux increases with the increase of stress ratio and fast.Under the action of bending stress and electric flux increased with the increase of the ratio of stress.

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运用有限元软件ABAQUS建立压印强化残余应力场的三维有限元模型,模拟计算压印强化过程中2B25-T351铝合金构件的三维残余应力场分布,模拟结果表明,压印痕底部残余应力沿厚度方向呈梯度分布,与表面距离越远,压应力水平越小。孔周围的残余应力分布比较集中,压印痕端头附近,孔边为相对均匀的残余压应力,其他位置为自平衡的残余拉应力;使用X射线衍射应力分析技术测量实际试样的残余应力,结果表明,实验测量值与有限元模拟值吻合较好;对压印强化前后试样进行疲劳性能试验,结果表明,压印强化在试件表面引入残余压应力,可降低裂纹萌生的几率及裂纹扩展的速率,压印强化后材料的疲劳寿命提高了近1.5倍。
The residual stress field of 2B25-T351 aluminum alloy caused by pressed strengthening was simulated by FEM using ABAQUS . The results show that the residual stress around indentation flaw possesses a gradient distribution across the thick-ness . Far away from the surface , the residual compressive stress decreased towards a stable value . The residual compressive stress around hole shows a centralized distribution , and the self-balanced residual tensile stress is located in other regions . The residual stress of the specimen measured by the X-ray agrees well with the FE simulation result . Furthermore , the effect of the pressed strengthening as the mechanical surface treatment on high cycle fatigue performance was investigated . The results show that pressed strengthening leads to a significant improvement in the fatigue life , and the main reason was that the pressed strengthening causes the residual compressive stress layer by which the crack initiation rate and propagation rate we

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目的 通过模拟颈椎间盘突出合并黄韧带病变所致的急性颈脊髓损伤,观察颈脊髓受压时前后方压应力的变化趋势,探讨前后方压应力与致压深度的关系.方法 采用10具新鲜成人尸体颈脊柱标本(C1 ～T1),通过前后方C4 ～ C5间骨窗伸入两根半球形测压杆,模拟颈椎间盘退变突出合并黄韧带病变时对颈脊髓前后方所形成的压迫.实验对颈脊髓前后方同时致压,致压深度最大和为椎管矢状径的60％,逐渐增加致压深度,分别测量不同致压深度下,颈脊髓脊膜前后方所受压应力的变化.结果 (1)前方致压深度一定,后方致压深度逐渐增加时,颈脊膜前方压应力无明显变化;颈脊膜后方压应力明显增大,其中致压深度为椎管中矢径的10％ ～ 20％时各相邻致压深度间颈脊髓后方压应力两两比较差异无统计学意义(P＞0.05);致压深度为椎管中矢径的30％～60％时各相邻致压深度间颈脊髓脊膜后方压应力两两比较差异有统计学意义(P＜0.05);(2)后方致压深度一定,前方致压深度依次递增时,颈脊膜前方压应力明显增大,其中致压深度为椎管中矢径的10％～20％时各相邻致压深度间颈脊髓后方压应力两两比较差异无统计学意义(P＞0.05);致压深度为椎管中矢径的30％ ～ 60％时各相邻致压深度间颈脊髓脊膜后方压应力两两比较差异有统计学意义(P＜0.05);颈脊膜后方压应力无明显变化.结论 颈脊髓脊膜前、后方所受压应力与致压深度呈非线性关系,所受压应力随致压深度增加而增大,前方或后方致压深度超过椎管中矢径的30％临界值后差异有统计学意义.
Objective To observe the anterior and posterior pressure change of the cervical spinal cord and to evaluate the relationship between the stress on cervical cord-meningeal complex (CCMC) compressed anteroposterior and the degree of canal occlusion by simulating cervical disc degeneration and cervical abnormal hgamentum flavum.Methods Specimens of 10 intact fresh cervical spine (C1-T1) from adult cadavers were collected in order to simulate cervical disc degeneration and abnormal ligamentumflavum by placing two hemispherical steel ball into the anterior and postierior side of the cervical spinal cordthrough the bone window of the C4-C5.The maximum depth of compression was 60％ of the spine canal anteroposterior diameter.Results (1) Under the anterior depth of a certain pressure with the increase of posterior pressure depth,the stress on the anterior of the CCMC had no significant change,and the stress on the posterior of the CCMC increased greatly with the increase of the degree of canal

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