测定低周疲劳抗力的应变频谱法

讨论了评估低周疲劳抗力的新方法，应变频谱法。应用光滑单轴向应变疲劳试样，通过频谱法测得了材料服役应力应变特性和低周疲劳抗力，给出了可靠的用局部应变法进行低周疲劳寿命预测的参数。     

应用当量应变法预测柴油机活塞的多维疲劳寿命

运用ADINAT／ADINA有限元程序分析了6110型柴油机活塞的三维温度场和三维应力应变场，并采用5种带缺口试件进行了多维高温低周疲劳寿命模拟试验，根据高温强度理论归纳了当量应变范围评价准则并将这一方法用于柴油机活塞的寿命预测，结果表明，这一方法是适合的，并且对柴油机设计与使用有一定的参考价值。     

30Cr1Mo1V转子钢低周疲劳性能及损伤演变规律研究

对３０Ｃｒ１Ｍｏ１Ｖ转子钢进行３组不同温度的低周疲劳试验，分析了该转子钢低周疲劳特性，给出了应变——寿命关系式，讨论了该转子钢的循环特性，推导了该转子钢在各个温度下的应变疲劳损伤演变方程和寿命估算方程。     

船舶柴油机活塞的热疲劳裂纹扩展评定

运用ADINAT／ADINA有限元程序分析了船舶柴油机活塞的三维温度场和三维应力应变场，并采用带中央环状预裂纹的圆柱形试件在单轴疲劳试验机上进行了热疲劳裂纹扩展寿命模拟试验，根据高温度理论和断裂力学理论归纳了当量J积分范围评分准则，并将这一准则用于活塞的裂纹扩展寿命分析和安全性评定，评定结果具有普遍参考价值。     

30Cr2MoV转子钢常温应变疲劳性能及损伤演变规律研究

能动对３０Ｃｒ２ＭｏＶ转子钢进行６组不同炉号的低周疲劳试验，给出了该材料循环稳定应力－应变曲线、应变－寿命关系、应力寿命关系以及应变疲劳损伤演变方程和寿命方程。由于试样取材有广泛的代表性，试验结果也基本上能代表该材料的疲劳性能。     

核电低压转子钢30Cr2Ni4MoV低周疲劳性能研究

对30Cr2Ni4MoV进行了拉伸试验和低周疲劳试验,对30Cr2Ni4MoV的拉伸性能进行了分析,得到了大直径转子不同部位力学性能的分布特征和30Cr2Ni4MoV的塑性模量。采用应变控制对30Cr2Ni4MoV进行不同应变幅的低周疲劳试验,结果表明,30Cr2Ni4MoV有明显的循环软化特征,30Cr2Ni4MoV转子钢的芯部与表面低周疲劳性能体现出较好的一致性,并拟合得到该材料Manson-Coffin公式与应变-寿命三参数公式。两种拟合公式都能较好地拟合原始数据,应变-寿命三参数公式能更好地反映材料高周疲劳性能。     

高效超超临界汽轮机转子钢FB2的低周疲劳特性研究

对再热温度为620℃的高效超超临界机组FB2转子钢的微观组织、拉伸性能进行了研究,采用轴向等幅低循环疲劳试验方法对FB2转子钢在室温和620℃下的低周疲劳性能进行了对比分析,并根据低周疲劳试验结果,建立了FB2转子钢塑性应变能和应变幅与循环周次间的关系。结果表明:FB2转子钢的微观组织为完全回火马氏体结构,有大尺寸BN夹杂析出;转子各取向的拉伸性能均匀,室温下的Rp0.2700 MPa,满足COST522项目要求;低周疲劳条件下表现为循环软化,循环应变-寿命满足Manson-Coffin关系;FB2转子钢的塑性应变能与对应的总应变幅和疲劳寿命在双对数坐标下呈线性关系,该关系可用于估算低周疲劳寿命。     

核电汽轮机末级长叶片材料的疲劳性能研究

为了掌握核电汽轮机末级长叶片材料1Cr12Ni3Mo2VN的疲劳性能,开展了低周疲劳试验研究,测试了材料的疲劳循环响应特性、循环应力-应变曲线和应变-寿命曲线,比较了不同疲劳寿命预测模型的预测结果.结果 表明:叶片材料在循环寿命的绝大部分期间都保持非常稳定的应力应变状态,仅在循环寿命初期表现出一定的循环软化特征;作为一种屈强比极高的材料,在循环周次105次及以上的疲劳寿命区域,循环塑性应变占总变形的比重变得非常小;断口形貌显示疲劳裂纹基本均起源于试样表面;Ramberg-Osgood模型和Manson-Coffin模型可以较好地拟合叶片材料的循环应力-应变曲线和应变-寿命曲线;Manson-Coffin模型和Langer模型对低周疲劳寿命预测均保持了较好的准确性;三参数幂函数能量模型在104循环周次以下的预测结果很好,需要更多的数据来提高其在更高循环周次的寿命预测准确性.     

增压器压气机叶轮低周疲劳强度有限元计算分析

作为涡轮增压器的核心零件，压气机叶轮主要失效模式是低周疲劳破坏。为了获得某新设计压气机叶轮的低周疲劳极限强度，确定叶轮低周疲劳试验转速，应用ANSYS有限元软件，主要考虑离心应力，采用周期循环模型、选用20节点等参单元计算方法、对该叶轮进行了强度计算和分析-得到了该叶轮的应力-转速曲线，为叶轮低周疲劳试验提供了理论依据。     

加载速率对3OCr1Mo1V汽轮机转子钢低周疲劳特性的影响

以30Cr1MolV汽轮机转子钢为研究材料,选取0.1%/s、0.3%/s和0.5%/s的加载速率,采用控制总应变的方法,在RDL 05电子蠕变疲劳试验机上研究了加载速率对材料低周疲劳特性的影响.同时,还提出在538℃下加载速率对30Cr1Mo1V汽轮机转子钢应力和低周疲劳寿命影响的关系式以及低周疲劳寿命与总应变幅值的关系式.结果表明:在538℃时,随着加载速率的提高,转子钢循环应力增大,低周疲劳寿命延长;在同一应变下,加载速率越大,所对应的应力幅值越大;随着应变幅值的增大,应力增大,低周疲劳寿命缩短.     

An Energy-Based Model for Void Nucleation Around Rigid Inclusion from Combined Mechanical Loading and Thermal Cycling

This article presents a new energy-based model for predicting void nucleation in materials under thermal cycling. Based on the micromechanical analysis of a unit cell, the local stress-strain field was calculated when it is under purely mechanical, thermal cycling, as well as in combination of these two types of loads. The results obtained from analytical calculations show that the imbalance in thermal stresses between the inclusions and matrix can assist the external load to cause void nucleation. Under certain conditions of mechanical and thermal cycling, both plastic strain and plastic energy density of the interface accumulate during each thermal cycle, which govern the void nucleation process.     

高周波活塞热冲击计算与分析

本文用6150柴油机燃气温度拟合成三角形热冲击模式，作为活塞顶面的热激励源，建立了高周波三角形热冲击及集总参数导热模型，计算该活塞顶面温度响应曲线及其变化规律，以作为活塞顶面热疲劳分析和研究的基础。     

加速热疲劳试验条件下内燃机受热件寿命的修正计算

本通过对低循环蠕变、高频载荷对为和低频疲劳的影响以及内燃机载荷谱对热疲劳寿命影响的研究，修正了无发动机加速热疲劳试验台的试验数据，并给出了实际内燃受热件寿命试验估算的修正公式。     

Structural integrity assessment of superheater outlet penetration tubeplate

In recent years, the Linear Matching Method (LMM) has been developed for the integrity assessment of the component subjected to cyclic thermal and mechanical loads. In this paper, the fatigue damage of a superheater outlet penetration tubeplate is assessed in detail using the LMM with an ABAQUS 3D finite element model. The significant thermal transients of the component are due to out of phase steam temperature oscillations. The primary loading on the component is from pressure (steam and gas) and system moment on the penetration and tailpipes. A transient thermal analysis is performed as the first step to determine the component temperature history during the cycle. Then these temperature solutions are used as an input to structural analysis to obtain the elastic stress history caused by these temperature loads. A shakedown analysis is thereafter carried out and the evaluation of the steady cyclic behaviour of the tubeplate during the steady state cycle is then achieved using the LMM. By assessing both constant and changing residual stress solutions associated with the steady state cycle, an LMM ratchet limit analysis is carried out to determine the capacity of the component subjected to the existing thermal transients to withstand additional primary loads including both pressure and moment. The total strain range over the steady state cycle is evaluated for the fatigue damage assessment. The comparisons of stress and strain range calculations for the out of phase temperature oscillations by the LMM and other methodologies prove the applicability and effectiveness of the LMM. The temperature-dependent elastic–plastic properties are adopted throughout the LMM assessment.     

Thermal Effects of Ferroelectric/Magnetic Materials Under Cyclic-Electric Loading

The temperature in the ferroelectric and ferromagnetic materials may rise due to energy dissipation under loading. Thermal effects on the mechanical behavior in ferroelectric/ferromagnetic materials are investigated theoretically in this paper. First, the influence of stresses induced by domain switching on the subsequent domain switching and domain reversal process in ferroelectrics is investigated. Based on the electrical saturation model, the influence of thermal effect on the domain switching is studied, and the changes of stress and electric intensity factors brought by thermal effect are obtained. The accumulative influence of temperature rise on the domain switching zone and fracture behavior of ferroelectrics under cycle electric field is studied. Second, the above approach of ferroelectric materials is extended to analyze the thermal effect in ferromagnetic materials. Using the magnetic saturation model, the temperature fields around the tip of a narrow elliptic hole are calculated under different conditions. It is found that the magnitude of temperature increment strongly depends upon the geometrical shape of the hole, the frequency and wave shape of the magnetic loading. This study is helpful to gain a deep understanding of the fracture and fatigue behavior of ferroelectric/ferromagnetic materials.     

基于不同启动方式的1 000 MW超超临界汽轮机高温部件低周疲劳损耗研究

为了解汽轮机寿命损耗情况,对汽轮机高温部件寿命影响因素进行分析。基于低周疲劳理论,建立汽轮机高温部件寿命损耗分析模型,采用定量计算方法分析1 000 MW超超临界机组冷态、热态启动方式下高温部件温度偏差变化情况,计算各边界条件下高温部件等效热应力及寿命损耗,并进行敏感性分析。结果表明：汽轮机低周疲劳寿命损耗率对高温部件温度偏差较为敏感,随着温度偏差的升高,汽轮机寿命损耗率大幅升高;相同的温度偏差出现在不同温度区间时,对汽轮机寿命损耗的影响亦不同,高温区间的温度偏差对寿命损耗率影响较大。汽轮机高温部件寿命评估可以为机组启动期间升温速度控制提供技术支持,降低汽轮机寿命损耗,提高机组运行安全性。     

Analysis of Thick-Walled Elastic-Plastic Sphere Subjected to Temperature Gradient

The aim of this work is the study of full thermal cycle (thermal loading and unloading) and the influence of linear hardening coefficients of the material on behavior of thick-walled elastic-plastic sphere subjected to thermal gradient. The influence of thermal cycle and hardening coefficients on the distribution of temperature and strains, on the position of elastic-plastic zone and current stresses, and in particular residual (inner stresses) arisen after the process of elastic unloading is analyzed. The role of residual stresses can be important in estimation of exploitation lifetime of loaded constructions and in analysis of thermal fatigue in loading-unloading thermal cycle. In analysis of the thick-walled sphere, the critical values of sphere geometric parameter β are also determined in the moment of formation of the second plastic zone on outer radius of sphere.     

电厂锅炉锅筒寿命计算

从锅炉锅筒运行中产生疲劳寿命损耗的实际情况出发,给出锅炉锅筒寿命计算的方法及计算机框图,并作实例计算。     

A study on fatigue crack growth in the high cycle domain assuming sinusoidal thermal loading

The assessment of fatigue crack growth due to turbulent mixing of hot and cold coolants presents significant challenges, in particular to determine the thermal loading spectrum and the associated crack growth. The sinusoidal method is a simplified approach for addressing this problem, in which the entire spectrum is replaced by a sine-wave variation of the temperature at the inner pipe surface. The loading frequency is taken as that which gives the shortest crack initiation and growth life. Such estimates are intended to be conservative but not un-realistic. Several practical issues which arise with this approach have been studied using newly-developed analytical solutions for the temperature and stress fields in hollow cylinders, in particular the assumptions made concerning the crack orientation, dimensions and aspect ratio. The application of the proposed method is illustrated for the pipe geometry and loadings conditions reported for the Civaux 1 case where through wall thermal fatigue cracks developed in a short time, but the problem is relevant also for fast reactor components.