ASTMD790-2017Word格式文档下载.docx

1、Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials1非增强和增强塑料和电绝缘材料的弯曲性能的标准试验方法This standard is issued under the fixed designation D790; the number immediately following the designation indicates the year of original adoption or, in the case of revision, th

2、e year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon （） indicates an editorial change since the last revision or reapproval.本标准以固定名称D790发布; 紧接指定的数字表示原始采纳的年份，或者在修订的情况下是最近一次修订的年份。 括号中的数字表示上次重新批准的年份。 上标epsilon（）表示自上次修订或重新批准以来的编辑更改。This standard h

3、as been approved for use by agencies of the U.S. Department of Defense.该标准已被美国国防部的机构批准使用。14Copyright ASTM InternationalProvided by IHS Markit under license with ASTMNo reproduction or networking permitted without license from IHSLicensee=Jilin Institute of Standardization/5993190001, User=BZYWXS126.

4、COM, BZY Not for Resale, 06/19/2018 00:44:21 MDT1. Scope*范围1.1 These test methods are used to determine the flexural properties of unreinforced and reinforced plastics, including high modulus composites and electrical insulating materials utilizing a three-point loading system to apply a load to a s

5、imply supported beam （specimen）. The method is generally applicable to both rigid and semi-rigid materials, but flexural strength cannot be determined for those materials that do not break or yield in the outer surface of the test specimen within the 5.0 % strain limit.这些测试方法用于确定未增强和增强塑料的弯曲性能，包括高模量复

6、合材料和电绝缘材料，利用三点加载系统将载荷施加到简支梁（试样）上。 该方法通常适用于刚性和半刚性材料，但对于在5.0应变极限内在试样外表面不破裂或屈服的那些材料，不能确定弯曲强度。1.2 Test specimens of rectangular cross section are injection molded or, cut from molded or extruded sheets or plates, or cut from molded or extruded shapes. Specimens must be solid and uniformly rectangular. T

7、he specimen rests on two supports and is loaded by means of a loading nose midway between the supports.1.2矩形横截面的试样是注塑成型的，或者是从模塑或挤出的板材或板材上切割下来的，或者是从模塑或挤压形状切割而成。 标本必须是实心且均匀的矩形。 样品放在两个支撑上，并通过支撑件中间的装载鼻加载。1.3 Measure deflection in one of two ways; using crosshead position or a deflectometer. Please note

8、that studies have shown that deflection data obtained with a deflectometer will differ from data obtained using crosshead position. The method of deflection measurement shall be reported.NOTE 1Requirements for quality control in production environments are usually met by measuring deflection using c

9、rosshead position. However, more accurate measurement may be obtained by using an deflection indicator such as a deflectometer.NOTE 2Materials that do not rupture by the maximum strain allowed under this test method may be more suited to a 4-point bend test. The basic difference between the two test

10、 methods is in the location of the maximum bending moment and maximum axial fiber stresses. The maximum axial fiber stresses occur on a line under the loading nose in 3-point bending and over the area between the loading noses in 4-point bending. A four-point loading system method can be found in Te

11、st Method D6272.1.4 The values stated in SI units are to be regarded as the standard. The values provided in parentheses are for informa- tion only.1.5 The text of this standard references notes and footnotes that provide explanatory material. These notes and footnotes （excluding those in tables and

12、 figures） shall not be considered as requirements of the standard.1.6 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 appro- priate safety and health practices and determine the

13、applica- bility of regulatory limitations prior to use.NOTE 3This standard and ISO 178 address the same subject matter, but differ in technical content.1.7 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Dec

14、ision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade （TBT） Committee.2. Referenced Documents2.1 ASTM Standards:2D618 Practice for Conditioning Plastics for Testing D638 Test Method for Tensile Properties of Plastics D883 Terminology Relating to PlasticsD4000 Classification System for Specifying Plastic Materi- alsD4101 Specification for Polypropylene Injection and Extru- sion MaterialsD5947 Test Methods for Physical Dimensions of Solid Plastics Specimens-,-,-D6272 Test Method for