Local Strain Measurement within Tendon

Abstract:  Tendon is a dense connective tissue, responsible for transmitting the forces generated by muscles to the skeleton. It is composed of a hierarchical arrangement of crimped collagen fibres, interspersed with proteoglycan matrix and cells, known as tenocytes. During physiological loading, tendons are subjected to strains in the region of 5–6%, which result in the straightening and realignment of the collagen fibres, generating variable local strain fields within the tendon. This study demonstrates a technique for analysing local strains within viable tendon explants, during both loading and unloading of the tissue. Samples were strained in a custom-designed rig, allowing real-time visualisation of cell nuclei, used as local discrete markers, on a confocal microscope. Results indicated that local strains within the fascicle are smaller than the applied strains, never exceeding 1.2%, even at 8% gross applied strain. By contrast, the sliding of adjacent collagen units was recorded at each strain increment in this study, reaching a mean maximum of 3.9% of the applied displacement. Loading–unloading studies indicated that sliding behaviour is reversible up to strains of 5%, and provides the major extension mechanism within the rat-tail tendon. This technique can be extended to further analyse shearing behaviour within the matrix.     

Analytical pyrolysis as a tool for the study of plastic coals

The technique of analytical pyrolysis has been used to characterize 40 similar mid-rank western Kentucky coals of widely differing ASTM Gieseler plasticity. Certain pyrolysis/g.c. variables were shown to correlate well with both ASTM Gieseler and isothermal plasticity. Highly plastic coals were shown to exhibit certain characteristic peaks in the 450 °C pyrogram which were absent in the pyrogram of the non-plastic coals. Two coals, representing the two extremes in plasticity, were selected for further study. After extraction with solvents such as DMF the characteristic peaks were absent in the 450 °C pyrogram of the extraction residue of the highly plastic coal. These peaks were also shown to decrease with increasing severity of air oxidation of the plastic coal. This technique appears to be a useful tool for the analysis of mid-rank plastic coals and supports the view that the substances contained in the bitumen fraction of these coals are involved in the development of the plastic state.     

从事放射性个人剂量监测分析与防护调查

为了能及时了解放射性工作人员的受照剂量，以便能够更好地保障放射工作人员的健康与安全，采用热释光测量法对包头地区从事放射性工作的工作人员进行了个人剂量监测，并对他们的剂量当量频数分布进行了统计与分析，对工作环境的防护进行了调查对比，就今后的工作提出建议。     

Experimental Stress-Strain Relations and Amplitude-Dependence of Wave Velocities in Sedimentary Rocks

Using the theory of microplasticity as the base, it is shown that the curvature of graph for the function describing the equation of state of rocks can change its sign depending on the value of the mechanical energy applied. The experiments on dolomites under the strains of order of 10_-6 reveal an increase in wave velocities as the amplitude grows.     

等径弯角挤压工艺(ECAEP)研究现状

等径弯角挤压是制备块状细晶材料的一种大塑性变形工艺，目前得到国内外高度重视．本文简要介绍了等径弯角挤压工艺的基本原理和变形特点，从理论上对其变形方式和机理进行了分析，并详细介绍了该工艺的应用领域。     

Effect of strain waveform on creep-fatigue life for Sn–8Zn–3Bi solder

This paper describes the creep‐fatigue life of Sn–8Zn–3Bi under push–pull loading. Creep‐fatigue tests were carried out using Sn–8Zn–3Bi specimens in fast–fast, fast–slow, slow–fast, slow–slow and hold–time strain waveforms. Creep‐fatigue lives in the slow–slow and hold‐time waveforms showed a small reduction from the fast–fast lives but those in the slow–fast and fast–slow waveforms showed a significant reduction from the fast–fast lives. Conventional creep‐fatigue life prediction methods were applied to the experimental data and the applicability of the methods was discussed. Creep‐fatigue characteristics of Sn–8Zn–3Bi were compared with those of Sn–3.5Ag and Sn–37Pb.     

大塑性变形制备纳米结构金属

细化晶粒是改善材料性能的有效手段，传统的压力加工技术(如轧制、挤压、拉拔和锻造等)可以细化晶粒(微米量级)。纳米结构金属由于具有很小的晶粒尺寸(20-500nm)和独特的缺陷结构，从而表现出优异的物理—力学性能。大塑性变形(SPD)具有将铸态粗晶金属的晶粒细化到纳米量级的巨大潜力，近年来已引起人们的极大关注。介绍了4种大塑性变形制备纳米结构金属的方法、原理、变形特点及应用，分析了纳米结构金属的强度和超塑性变形特征，以及当前研究中存在的主要问题，并对大塑性变形技术的应用前景进行了展望。     

实验应变／应力模态分析若干问题的进展评述

本文评述了实验应变／应力模态分析进展的若干基本问题。主要是：应变响应与位移响应的关系；应变频响函数矩阵的特点及其测量方法；应变模态的加权正交性及其识别方法；以及其他问题。     

橡塑共混热塑性弹性体的形态结构与性能

综述了影响共混热塑性弹性体的形态结构与性能的主要因素。