1.1 这些试验方法通过与长轴剪切变形相关的木结构面板的厚度特性确定剪切。使用中的木结构面板包括胶合板、定向刨花板、单板和木基层复合材料。包括三种在应用上有所不同的试验方法: 试验方法 部分 A. 小面板剪切试验 5. B 大面板剪切试验 6. C 双轨剪切试验 7. 试验方法的选择部分取决于试验目的、试验材料的特性和设备可用性。一般来说，当设备、试验材料数量和实验计划允许时，首选大样本的试验方法B或C。 1.1.1 试验方法A:小面板剪切试验- 本试验方法适用于测试均匀材料的小样本，包括研究晶粒方向或取向的影响，以及许多原材料和制造工艺变量的影响，这些变量均匀地影响整个样本的剪切性能。该试验方法不适用于确定等级和制造特征的影响，例如密度变化、结和试样内的芯隙。 1.1.2 试验方法B:大面板剪切试验- 该试验方法被视为提供了最准确的刚度模量，因此建议用于试验结构应力分析研究中所用材料的弹性试验。 该试验方法还为透明材料提供了良好的抗剪强度值。然而，尽管试样尺寸较大，但故障通常仅发生在试验区域周边的狭窄区域。由于周长框架较重，该特性导致该试验方法通常不适合确定等级和制造效果，例如密度变化、芯隙和并非均匀分布在整个面板上的结。通常，只有在需要在高周长框架条件下这些因素的影响的情况下，才应采用试验方法。 1.1.3 试验方法C:双轨剪切试验- 本试验方法适用于各种材料和问题。 试样的制造和试验程序比试验方法A和B稍微简单一些。试样可以平行于其24 in自由剪切。（610 mm）长度尺寸在8英寸范围内的任何位置。轨道之间的宽度（203 mm）。因此，该试验方法非常适合确定等级和制造效果，例如占用和影响小面积的芯隙和节点。该试验方法不太适合测定刚度模量，但在针对应变分布效应进行调整时，近似于通过试验方法B获得的值。当预期薄弱面垂直于轨道时，该测试方法模拟了重框架的影响，而当平行于轨道时，根本没有框架。 注1: 试验方法中包含了基于这种双轨剪切方法原理的较小规模版本 D1037号 第27节。测试方法的结果 D1037号 第27节可能不等同于试验方法的结果 D2719 方法C。 1.2 当这些试验方法应用于透明直纹单板胶合板时，发现三种试验方法之间存在显著差异，大小从中到小。因此，在比较试验结果时，建议始终使用相同的试验方法。 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）。本标准的用户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（TBT）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》中确立的国际公认标准化原则制定的。 ====意义和用途====== 3.1 通过这些测试方法获得的木材结构面板在剪切厚度下的强度和刚度模量，是许多木材面板结构组件（如带面板角撑板的桁架、箱梁、折板屋顶和空间平面结构，以及地板和屋顶隔板和剪力墙）的严格设计所必需的。 在典型的屋顶板和护套应用中，以及在板条箱和运输集装箱中，这些特性是次要的。 3.2 通过切片或旋转剥离产生的单板可能包含与单板刀侧纹理平行的细纹或分离，这些细纹或分离是在刀被强行穿过木材时产生的。这些检查被称为“刀形检查”，以区别于压杆作用力可能在单板另一侧形成的偶尔检查和干燥引起的检查。研究发现，刀片检查的平均深度对胶合板的剪切性能有很大影响，对复合板中的单板可能具有重要意义。在这些试验方法中，建议测量刀片检查的深度。 3.3 为了控制或定义影响剪切性能的其他变量，这些试验方法需要测定含水量和失效时间。建议在受控大气中调节试验材料并测定比重。

1.1 These test methods determine the shear through-the-thickness properties of wood structural panels associated with shear distortion of the major axis. Wood structural panels in use include plywood, oriented strand board, and composites of veneer and of wood-based layers. Three test methods are included which differ somewhat in their application: Test Method Section A. Small Panel Shear Test 5 B. Large Panel Shear Test 6 C. Two-Rail Shear Test 7 The choice of test method will be determined in part by the purpose of the tests, characteristics of test material, and equipment availability. In general, Test Method B or C for large specimens is preferred when equipment, amount of test material, and experimental plan permit. 1.1.1 Test Method A: Small Panel Shear Test— This test method is suitable for testing small samples of uniform material including investigations of the effects of grain direction or orientation and of many raw materials and manufacturing process variables which influence shear properties uniformly throughout the specimen. The test method is unsuited for determining effects of grade and manufacturing features such as density variations, knots, and core gaps within the specimen. 1.1.2 Test Method B: Large Panel Shear Test— This test method is regarded as giving the most accurate modulus of rigidity and is therefore recommended for elastic tests of materials to be used in stress analysis studies of test structures. This test method also yields excellent shear strength values for clear material. However, in spite of the large size of the specimen, failures generally occur only in narrow zones at the perimeter of the test area. This characteristic, a result of the heavy perimeter framing, causes this test method to be generally unsuited for determining grade and manufacturing effects such as density variations, core gaps, and knots that are not uniformly distributed throughout the panel. Generally, only in cases where effects of these factors under conditions of heavy perimeter framing are desired, should the test method be applied. 1.1.3 Test Method C: Two-Rail Shear Test— This test method is applicable to a wide variety of materials and problems. The specimen fabrication and test procedures are somewhat simpler than in Test Methods A and B. The specimen is free to shear parallel to its 24-in. (610-mm) length dimension anywhere within the 8-in. (203-mm) width between rails. Thus, the test method is well suited for determining grade and manufacturing effects such as core gaps and knots occupying and affecting small areas. The test method is not so ideally suited for determination of modulus of rigidity, but when adjusted for strain distribution effects, values approximating those obtained by Test Method B result. The test method simulates effects of heavy framing when expected planes of weakness are oriented perpendicular to rails and no framing at all when parallel to rails. Note 1: A smaller scale version based on the principles of this two-rail shear method is contained in Test Methods D1037 Section 27. The results from Test Methods D1037 Section 27 may not be equivalent to the results from Test Methods D2719 Method C. 1.2 Significant differences, moderate to small in magnitude, among the three test methods have been found to exist when these test methods are applied to plywood of clear straight-grained veneers. Therefore, when comparisons are made among test results, it is recommended that the same test method be used throughout. 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 ====== 3.1 The strength and modulus of rigidity of wood structural panels in shear through-the-thickness obtained by these test methods are required for the rigorous design of many lumber-panel structural components such as trusses with panel gussets, box beams, folded plate roofs, and space plane structures, as well as floor and roof diaphragms, and shear walls. These properties are of secondary importance in typical roof deck and sheathing applications, and in crates and shipping containers. 3.2 Veneer produced by slicing or rotary peeling may contain fine checks or separations parallel to the grain on the knife side of the veneer that are produced as the knife is forced through the wood. These checks are termed “knife checks” to distinguish them from occasional checks that may be formed on the opposite side of the veneer by forces at the compression bar, and from checks caused by drying. Average depth of knife checks has been found to strongly influence shear properties in plywood panels and may be of significance in veneer incorporated in composite panels. Measurement of depth of knife checks is recommended in these test methods. 3.3 To control or define other variables influencing shear properties, these test methods require determination of moisture content and elapsed time to failure. The conditioning of test material in controlled atmosphere and determination of specific gravity are recommended.