1.1 该试验方法将定义形状记忆合金（SMA）材料和圆形横截面部件在恒定扭矩下的热机械循环程序。当形状记忆合金在恒定的施加扭矩下通过相变进行热循环时，该测试方法将测量相变特性，如相变温度、致动剪切应变和残余剪切应变。本试验旨在为形状记忆合金材料的特性选择、质量控制、设计容许值和致动器设计提供数据。 1.2 以国际单位制表示的数值应视为标准。 本标准中不包括其他计量单位。 1.3 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的使用者有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 1.4 本国际标准是根据世界贸易组织技术性贸易壁垒委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认的标准化原则制定的。 ===意义和用途====== 4.1 恒定扭矩热循环试验确定了剪切应力对形状记忆合金的转变特性的影响，如转变温度、致动剪切应变和残余剪切应变。本试验旨在为形状记忆合金材料的特性选择、质量控制、设计容许值和致动器设计提供数据 ( 1- 3. ) 。 5. 测试应用于一个热循环，但可用于供应商和客户之间商定的重复热循环。 4.2 样品运动的测量与许多形状记忆致动器应用密切相关，并提供适用于材料功能的结果。 4.3 该试验方法可用于圆柱形试样，如金属丝、圆管或棒材。因此，它能够提供对半成品形式的产品的评估。 4.4 该试验方法提供了一种简单的方法，通过加热和冷却试样，使其在扭矩下完全热变形，来确定转变温度。 4.5 该测试方法也可用于评估由LCT和UCT设置并由用户和客户商定的部分转换周期。部分和全部转化热循环的示例见 图2 。 图2 剪切应力和上循环温度对试验结果的影响 注1: A） UCT足以完成奥氏体转变。B） UCT不足以完成奥氏体转变。“τ”是施加的剪切应力。 4.6 该测试方法可用于经过训练和加工的半成品材料，通过将LCT和UCT处的剪切应变与扭矩设置进行比较来测量双向形状记忆效应（TWSME），从而使相应的剪切应力不应超过7MPa。为了以这种方式确定TWSME，建议根据 5.7 。 4.7 这种测试方法有助于质量控制、规范验收和研究。 4.8 由于剪切应变和剪切应力对转变的影响，从该试验方法得出的转变温度可能与通过其他试验方法获得的转变温度不一致。 4.9 弹簧、非圆形横截面试样或其他半成品等部件可以使用客户和供应商同意的方法进行测试。应根据在试样有效区域末端测量的扭矩和旋转来确定试验参数和结果。

1.1 This test method will define procedures for thermomechanical cycling of shape memory alloys (SMA) material and components with circular cross-sections under constant torque. This test method will measure the transformation properties such as transformation temperatures, actuation shear strain and residual shear strain, when a shape memory alloy is thermally cycled through the phase transformation under a constant applied torque. This test is done to provide data for the characterization selection of shape memory alloy materials, quality control, design allowables and actuator design. 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 4.1 Constant torque thermal cycling tests determine the effect of shear stress on the transformation properties such as transformation temperatures, actuation shear strain and residual shear strain of a shape memory alloy. This test is done to provide data for the characterization selection of shape memory alloy materials, quality control, design allowables and actuator design ( 1- 3 ) . 5 The tests should be used for one thermal cycle but may be used for repeated thermal cycles as agreed upon between supplier and customer. 4.2 Measurement of the specimen's motion closely parallels many shape memory actuator applications and provides a result that is applicable to the function of the material. 4.3 This test method may be used for cylindrical specimens such as wire, round tube or bar forms. Thus, it is able to provide an assessment of the product in its semi-finished form. 4.4 This test method provides a simple method for determining transformation temperatures by heating and cooling specimens through their full thermal transformation under torque. 4.5 This test method may also be used to evaluate partial transformation cycles as set by the LCT and UCT and agreed upon between the user and customer. Examples of partial and full transformation thermal cycles are provided in Fig. 2 . FIG. 2 Effects of Shear Stress and Upper Cycle Temperature on Test Results Note 1: A) UCT sufficient for complete Austenitic transformation. B) UCT not sufficient for complete Austenitic transformation. “τ” is the applied shear stress. 4.6 This test method can be used on trained and processed material in a semi-finished form to measure Two Way Shape Memory Effect (TWSME) by comparing the shear strain at the LCT and UCT with a torque set such that the corresponding shear stress shall not exceed 7 MPa. For determining TWSME in this manner it is suggested that a full transformation cycle be performed in accordance with 5.7 . 4.7 This test method is useful for quality control, specification acceptance, and research. 4.8 Transformation temperatures derived from this test method may not agree with those obtained by other test methods due to the effects of shear strain and shear stress on the transformation. 4.9 Components such as springs, specimens with non-circular cross-sections or other semi-finished parts can be tested using this method as agreed upon by the customer and supplier. Test parameters and results shall be determined with respect to torque and rotation measured at the ends of the active region of the specimen.