非常抱歉，我们暂时无法提供预览，您可以试试： 免费下载 ASTM D790-2015e1 前三页，或者稍后再访问。
如果您需要购买此标准的全文，请联系： 。
点击下载后，生成下载文件时间比较长，请耐心等待......
5.1x00a0;Flexural properties as determined by this test method are especially useful for quality control and specification purposes. They include:
5.1.1x00a0;Flexural Stress (x03c3;f)x2014;When a homogeneous elastic material is tested in flexure as a simple beam supported at two points and loaded at the midpoint, the maximum stress in the outer surface of the test specimen occurs at the midpoint. Flexural stress is calculated for any point on the load-deflection curve using equation (Eq 3) in Section 12 (see Notes 5 and 6).
Note 5:x00a0;Eq 3 applies strictly to materials for which stress is linearly proportional to strain up to the point of rupture and for which the strains are small. Since this is not always the case, a slight error will be introduced if Eq 3 is used to calculate stress for materials that are not true Hookean materials. The equation is valid for obtaining comparison data and for specification purposes, but only up to a maximum fiber strain of 5 % in the outer surface of the test specimen for specimens tested by the procedures described herein.
Note 6:x00a0;When testing highly orthotropic laminates, the maximum stress may not always occur in the outer surface of the test specimen.5 Laminated beam theory must be applied to determine the maximum tensile stress at failure. If Eq 3 is used to calculate stress, it will yield an apparent strength based on homogeneous beam theory. This apparent strength is highly dependent on the ply-stacking sequence of highly orthotropic laminates.
5.1.2x00a0;Flexural Stress for Beams Tested at Large Support Spans (x03c3;f)x2014;If support span-to-depth ratios greater than 16 to 1 are used such that deflections in excess of 10 % of the support span occur, the stress in the outer surface of the specimen for a simple beam is reasonably approximated using equation (Eq 4) in 12.3 (see Note 7).
Note 7:x00a0;When large support span-to-depth ratios are used, significant end forces are developed at the support noses which will affect the moment in a simple supported beam. Eq 4 includes additional terms that are an approximate correction factor for the influence of these end forces in large support span-to-depth ratio beams where relatively large deflections exist.
5.1.3x00a0;Flexural Strength (x03c3;fM)x2014;Maximum flexural stress sustained by the test specimen (see
Copyright ©2007-2022 ANTPEDIA, All Rights Reserved
京ICP备07018254号 京公网安备1101085018 电信与信息服务业务经营许可证：京ICP证110310号