Electron microscopic observations and DNA chain fragmentation studies on apoptosis in bone tumor cells induced by ~(153)Sm-EDTMP

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Energetics of Plastic Deformation of Metastable Austenitic Stainless Steel

The change in the internal energy during uniaxial tensile deformation of austenitic stainless steels EN 1.4301 (AISI 304) and EN 1.4318 (AISI 301LN) was determined by measuring the extent of γ→α'‐martensite transformation and the temperature increase of the samples. From the results the fraction of the stored energy of cold work and the free energy change related to the strain‐induced γ→α'‐martensite transformation were determined. The fraction of stored energy varied around 0.4. With the metastable steel grades the free energy change related to the γ→α'‐martensite transformation was found to vary between ‐98 MJ/m³ and ‐206 MJ/m³ depending on the austenite stability of the steel. Furthermore, the magnitude of the mechanical driving force was estimated by comparing the results with the free energy change of thermally induced transformation.     

铁铝酸盐复合膨胀水泥化学预应力机理及其应用研究

本文阐述铁铝酸盐自应力混凝土的主要物理力学特征.研究了限制膨胀应变与配筋率之间的定量函数关系.通过正交试验和方差分析,确定了复合外加剂对其性能的影响.针对其在自应力管中的应用,提出多层中空圆柱理论计算模型,按弹性理论计算出自应力管初始应力分布规律.对比以前的线性理论计算误差,给出相应的修正系数.本文对类似的自应力混凝土,具有普遍的指导意义.     

Hardness-stress-strain correlation in aluminium—A simpler alternative to visioplasticity in metal forming

Local stress and strain variations in the deformation zone can be ascertained by measuring hardness. Hardness is correlated with strain and stress. The expressions discussed later are useful in determining the local variations in stress and strain from hardness measurement. It is a simple method compared to visioplasticity. One can estimate the forces required for a forming process. It helps in the choice of equipment, design of tooling and selection of lubricant for the particular process.     

填充HDPE复合材料基体结晶形态的控制因素

本文以HDPE/玻璃微珠和HDPE/CaCO₃体系为研究模型,通过扫描电镜、红外光谱、偏光显微、小角激光散射和材料力学性能实验等方法考察了这两种体系的界面粘结性、填料含量、粒径及试样成型冷却速率等与其材料性能及基体结晶形态变化间的关系。实验结果表明;在复合材料试样成型过程中,因基体树脂冷却收缩而产生的界面应力可干扰基体中球晶的生长环境,应变诱导填料颗粒周围基体树脂的结晶,促使其表面伸展链晶体结构的形成,并由此而明显改变了复合材料的耐热性;复合材料的界面粘结性是产生这种应变诱导作用,并控制异相结晶的关键。     

Inverse Analysis of Axisymmetrical Compression of HSLA Steel

The objective of the present work is to further explore the problem of selection of the flow stress function which will give the best agreement with experiments for a wide range of the Zener‐Hollomon parameter. Analysis of various flow stress functions was performed, with particular emphasis on the Zerilli‐Armstrong model. Inverse analysis was successfully applied to identify the flow stress model for microalloyed steels deformed in ferrite, two‐phase and austenite regions. Inverse method is applied to interpret the results of the axisymmetrical compression tests performed for HSLA steel samples on a Gleeble 3800 and Split Hopkinson Pressure Bar. Sensitivity analysis is performed based on local and global methods. The objective of the sensitivity analysis in the present study is the evaluation to what extent the selected coefficients in the rheological model influence the result of simulations. In the considered tests this result is represented by two dependent variables, the load and the shape of the sample (barrelling). It is confirmed that the Zerilli‐Armstrong equations should be applied at very high strain rates. Physical meaning is an advantage of this model. Difficulties with identification are the main disadvantage.     

High temperature low cycle fatigue

Fatigue at high temperature is a complex phenomenon as it is influenced by a number of time-dependent processes which become important at elevated temperatures. These processes include creep, oxidation, phase instabilities and dynamic strain ageing (DSA), acting either independently or synergistically influence fatigue behaviour, often lowering the fatigue life. Current design approaches employ linear summation of fatigue and creep damage with suitable factors on permissible damage to take care of uncertainties in interaction between cyclic and time-dependent processes. It is, therefore, important to develop a deeper understanding of the processes that occur during high temperature fatigue so that realistic life predictions could be made. Results on the high temperature fatigue behaviour of austenitic stainless steels, ferritic steels and nickel base alloys are presented here. The important mechanisms of interaction of high temperature time-dependent processes with fatigue under various conditions are discussed in detail. Emphasis is placed on cyclic stress response, fatigue life, deformation substructure and fracture behaviour. This is followed by a review of important life prediction techniques under combined creep-fatigue loading conditions. Life prediction techniques considered here include linear damage summation, strain range partitioning, ductility exhaustion approach, frequency modified and frequency separation methods, techniques based on hysteresis energy and damage rate models, and methods based on crack-cavitation interation models.     

Measuring the load eccentricity in helical compression springs

An experimental device able to detect the load eccentricity in helical compression springs is described. The theory underlying the resolution of measured bending strains of the apparatus into effective load eccentricity is discussed. Laboratory results are offered for heavy duty springs and compared to theoretical estimates retrieved from the literature.     

等径侧向挤压应变分析

对等径侧向挤压变形的应变进行了深入的分析，应用平面纯剪切变形应变分析的结果，得到了等径侧向挤压变形真应变和等效真应变的计算公式，分析了循环等径Ｓ型侧向挤压真空应变和等效真应变的变化规律。