ISO 899-2:2003 塑料.拉伸蠕变的测定 第2部分： 三点负载法测定抗屈蠕变

标准编号：ISO 899-2:2003

中文名称：塑料.拉伸蠕变的测定 第2部分： 三点负载法测定抗屈蠕变

英文名称：Plastics — Determination of creep behaviour — Part 2: Flexural creep by three-point loading

发布日期：2003-06

标准范围

ISO 899-2:20 03规定了在诸如预处理、温度和湿度的规定条件下测定标准试样形式的塑料的弯曲蠕变的方法。它仅适用于跨中加载的简单自由支承梁（三点加载试验）。该方法适用于刚性和半刚性非增强、填充和纤维增强塑料材料（定义见ISO 472），其形式为哑铃形试样，由片材或模制制品直接模制或机加工而成。注意，由于纤维取向的差异，该方法可能不适用于某些纤维增强材料。该方法旨在为工程设计和研发目的提供数据。用于工程设计目的的数据需要使用引伸计来测量样品的标距长度。用于研究或质量控制目的的数据可以使用夹具之间距离的变化（标称延伸）。弯曲蠕变可能随着试样制备和尺寸以及试验环境的差异而显著变化。试样的热历史也会对其蠕变行为产生深远的影响（见附件A）。因此，当需要精确的比较结果时，必须仔细控制这些因素。如果弯曲蠕变特性用于工程设计目的，塑料材料应在广泛的应力、时间和环境条件下进行测试。该方法可能不适用于测定刚性泡沫塑料的弯曲蠕变（在这方面请注意ISO 1209-1，泡沫塑料，刚性-弯曲试验-第1部分:弯曲试验，和ISO 1209-2，泡沫塑料，刚性-弯曲试验-第2部分:弯曲性能的测定）。

ISO 899-2:2003 specifies a method for determining the flexural creep of plastics in the form of standard test specimens under specified conditions such as those of pretreatment, temperature and humidity. It applies only to a simple freely supported beam loaded at mid-span (three-point-loading test).The method is suitable for use with rigid and semi-rigid non-reinforced, filled and fibre-reinforced plastics materials (see ISO 472 for definitions) in the form of dumb-bell-shaped test specimens moulded directly or machined from sheets or moulded articles.NOTE The method may be unsuitable for certain fibre-reinforced materials due to differences in fibre orientation.The method is intended to provide data for engineering-design and research and development purposes. Data for engineering-design purposes requires the use of extensometers to measure the gauge length of the specimen. Data for research or quality-control purposes may use the change in distance between the grips (nominal extension).Flexural creep may vary significantly with differences in specimen preparation and dimensions and in the test environment. The thermal history of the test specimen can also have profound effects on its creep behaviour (see Annex A). Consequently, when precise comparative results are required, these factors must be carefully controlled.If flexural-creep properties are to be used for engineering-design purposes, the plastics materials should be tested over a broad range of stresses, times and environmental conditions.The method may not be suitable for determining the flexural creep of rigid cellular plastics (attention is drawn in this respect to ISO 1209-1, Cellular plastics, rigid -- Flexural tests -- Part 1: Bending test, and ISO 1209-2, Cellular plastics, rigid -- Flexural tests -- Part 2: Determination of flexural properties).

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