1.1 本规程提供了修改层压板准静态压痕和跌落重量冲击试验方法的说明，以确定夹层结构的抗损伤性能。允许的芯材形式包括具有连续粘合表面（如轻木和泡沫）以及具有不连续粘合表面的芯材（如蜂窝、特拉斯芯材和纤维增强芯材）。 1.2 本规程是对试验方法的补充 D6264/D6264米 （用于准静态压痕试验）和 D7136/D7136米 （用于落锤冲击试验），并规定对夹层试样进行试验。本规程未规定几个重要的试样参数（例如，表面厚度、芯部厚度和芯部密度）；然而，可重复的结果要求指定并报告这些参数。 1.3 提供了三个测试程序。程序A和B对应 D6264/D6264米 分别用于刚性背衬和边缘支撑试验条件的试验程序。程序C对应于 D7136/D7136米 测试程序。所有三种程序都适用于根据试验方法对夹层试样进行损伤，为随后的损伤容限试验做准备 8287/8287米 （压缩载荷）和实践 8388/8388米 （弯曲荷载）。 1.4 一般来说，由于弯曲刚度和支撑夹具特性对损伤形成的影响较小，程序A被认为是比较损伤抗力评估的最合适程序。 然而，测试程序和相关支撑条件的选择应考虑到预期的结构应用，因此，程序B和C可能更适合用于某些应用的比较目的。 1.5 单位- 以国际单位制或英寸磅单位表示的数值应单独视为标准。每个系统中规定的值不一定是完全相等的；因此，为了确保符合标准，每个系统应独立使用，并且两个系统的值不得合并。 1.5.1 在文本中，英寸磅单位显示在括号中。 1.6 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。 1.7 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====== 5.1 本规程提供了允许测试方法的补充说明 D6264/D6264米 （用于准静态压痕试验）和 D7136/D7136米 （用于落锤冲击试验），以确定夹层结构的抗损伤性能。平面外集中力对损伤的敏感性是许多使用夹层结构制造的结构的主要设计问题之一。夹层板的抗损伤性能知识对产品开发和材料选择很有用。 5.2 夹层抗损伤测试可用于以下目的: 5.2.1 定量确定饰面几何结构、饰面堆叠顺序、饰面-芯体界面、芯体几何结构（单元尺寸、单元壁厚、芯体厚度等）、芯体密度、芯体强度、加工和环境变量对特定夹芯板对集中准静态压痕力、落锤冲击力或冲击能量的抗损伤性的影响。 5.2.2 定量比较不同面层、芯层或粘合材料的夹层结构的抗损伤参数的相对值。 损伤响应参数可以包括凹痕深度、损伤尺寸和位置、压痕或冲击力大小、冲击能量大小以及力与时间的关系曲线。 5.2.3 为随后的损伤容限测试（如测试方法）赋予试样损伤 8287/8287米 和实践 8388/8388米 。 5.2.4 准静态压痕试验也可用于识别特定的损伤事件序列（只有在落锤冲击试验后才能识别最终损伤状态）。 5.3 使用这些实践获得的性能可以为具有类似材料、几何形状、堆叠顺序等的夹层结构的预期抗损伤能力提供指导。然而，必须理解的是，夹层结构的抗损伤性在很大程度上取决于几个因素，包括几何形状、厚度、刚度、质量、支撑条件等。 5.3.1 力/能量和由此产生的损伤状态之间的关系可能由于这些参数的差异而产生显著差异。 例如，使用边缘支撑试样获得的性能更有可能反映夹层面板远离下部结构附件的抗损伤特性，而刚性支撑试样更有可能反映下部结构局部面板的抗平面外变形性能。类似地，边缘支撑的冲击试样的性能预计与具有相等长度和宽度尺寸的夹层板的性能相似，而与明显大于试样的面板的性能相比，后者往往会将更大比例的冲击能量转移到弹性变形中。 5.3.2 程序A（使用刚性背衬试样的准静态压痕）被认为是比较不同材料、几何形状、堆叠顺序等夹层板抗损伤特性的最合适程序。这是因为刚性背板能够抵抗试样的平面外变形，因此与边缘支撑试验相比，夹层弯曲刚度和支撑几何结构对损伤萌生和生长行为的影响较小。 然而，应该注意的是，使用刚性背衬试样观察到的抗损伤行为可能不会严格转化为边缘支撑应用。例如，使用具有高压缩刚度或强度的芯材或两者（例如，轻木）的夹层结构可能在刚性支撑试验中表现出优异的性能，但这种性能可能不会严格转化为边缘支撑试验，在边缘支撑试验中，芯材剪切刚度、芯材剪切强度和夹层板弯曲刚度对试验结果有更大的影响。 因此，在选择用于比较目的的测试程序时，必须考虑预期的评估和结构应用，因此，程序B和C的使用可能更适合某些应用。 5.3.3 对于某些结构应用，在落锤冲击试验中使用刚性背衬试样可能是合适的。本规程中未包括此类测试的具体程序，但程序C中详细说明的一般方法可能有助于在进行此类评估时作为指导材料。 此类试验应考虑到使用刚性支撑条件的影响，例如其对接触力和冲击下夹层变形的影响，以及对试验装置的潜在损坏。 5.4 标准压头和冲击器的几何形状具有钝的半球形尖端。从历史上看，与使用锋利尖端观察到的类似压痕或冲击相比，这些尖端几何形状在给定的外部损伤量下会产生更大的内部损伤。 根据所检查的抗损伤特性，替代压头和冲击器的几何形状可能是合适的。例如，尖锐尖端几何形状的使用可能适用于某些表面穿透阻力评估。 5.5 一些测试组织可能希望将这些实践与随后的损伤容限测试方法（如测试方法 8287/8287米 或实践 8388/8388米 )评估包含特定损伤状态的试样的残余强度，例如定义的凹痕深度、损伤几何形状、损伤位置等。 在这种情况下，测试组织应使用这些做法，在不同的能量水平下，使几个试样或一块大面板受到多个压痕或冲击，或两者兼而有之。然后可以建立力或能量与期望的损伤参数之间的关系。根据试验方法进行的后续残余强度试验 8287/8287米 或实践 8388/8388米 然后可以使用使用期望产生期望损伤状态的内插能量或力水平损伤的试样来执行。

1.1 This practice provides instructions for modifying laminate quasi-static indentation and drop-weight impact test methods to determine damage resistance properties of sandwich constructions. Permissible core material forms include those with continuous bonding surfaces (such as balsa wood and foams) as well as those with discontinuous bonding surfaces (such as honeycomb, truss cores and fiber-reinforced cores). 1.2 This practice supplements Test Methods D6264/D6264M (for quasi-static indentation testing) and D7136/D7136M (for drop-weight impact testing) with provisions for testing sandwich specimens. Several important test specimen parameters (for example, facing thickness, core thickness and core density) are not mandated by this practice; however, repeatable results require that these parameters be specified and reported. 1.3 Three test procedures are provided. Procedures A and B correspond to D6264/D6264M test procedures for rigidlybacked and edge-supported test conditions, respectively. Procedure C corresponds to D7136/D7136M test procedures. All three procedures are suitable for imparting damage to a sandwich specimen in preparation for subsequent damage tolerance testing in accordance with Test Method D8287/D8287M (compressive loading) and Practice D8388/D8388M (flexural loading). 1.4 In general, Procedure A is considered to be the most suitable procedure for comparative damage resistance assessments, due to reduced influence of flexural stiffness and support fixture characteristics upon damage formation. However, the selection of a test procedure and associated support conditions should be done in consideration of the intended structural application, and as such Procedures B and C may be more appropriate for comparative purposes for some applications. 1.5 Units— The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined. 1.5.1 Within the text the inch-pound units are shown in brackets. 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 appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.7 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 ====== 5.1 This practice provides supplemental instructions that allow Test Methods D6264/D6264M (for quasi-static indentation testing) and D7136/D7136M (for drop-weight impact testing) to determine damage resistance properties of sandwich constructions. Susceptibility to damage from concentrated out-of-plane forces is one of the major design concerns of many structures made using sandwich constructions. Knowledge of the damage resistance properties of a sandwich panel is useful for product development and material selection. 5.2 Sandwich damage resistance testing can serve the following purposes: 5.2.1 To establish quantitatively the effects of facing geometry, facing stacking sequence, facing-to-core interface, core geometry (cell size, cell wall thickness, core thickness, etc.), core density, core strength, processing and environmental variables on the damage resistance of a particular sandwich panel to a concentrated quasi-static indentation force, drop-weight impact force, or impact energy. 5.2.2 To compare quantitatively the relative values of the damage resistance parameters for sandwich constructions with different facing, core or adhesive materials. The damage response parameters can include dent depth, damage dimensions and location(s), indentation or impact force magnitudes, impact energy magnitudes, as well as the force versus time curve. 5.2.3 To impart damage in a specimen for subsequent damage tolerance tests, such as Test Method D8287/D8287M and Practice D8388/D8388M . 5.2.4 Quasi-static indentation tests can also be used to identify a specific sequence of damage events (only the final damage state is identifiable after a drop-weight impact test). 5.3 The properties obtained using these practices can provide guidance in regard to the anticipated damage resistance capability of sandwich structures with similar materials, geometry, stacking sequence, and so forth. However, it must be understood that the damage resistance of a sandwich structure is highly dependent upon several factors including geometry, thickness, stiffness, mass, support conditions, and so forth. 5.3.1 Significant differences in the relationships between force/energy and the resultant damage state can result due to differences in these parameters. For example, properties obtained using edge-supported specimens would more likely reflect the damage resistance characteristics of a sandwich panel away from substructure attachments, whereas rigidly-backed specimens would more likely reflect the behavior of a panel local to substructure which resists out-of-plane deformation. Similarly, edge-supported impact test specimen properties would be expected to be similar to those of a sandwich panel with equivalent length and width dimensions, in comparison to those of a panel significantly larger than the test specimen, which tends to divert a greater proportion of the impact energy into elastic deformation. 5.3.2 Procedure A (quasi-static indentation using a rigidly-backed specimen) is considered to be the most suitable procedure for comparison of the damage resistance characteristics of sandwich panels of varying material, geometry, stacking sequence and so forth. This is because the rigid backing plate resists out-of-plane deformation of the specimen, such that the sandwich flexural stiffness and support geometry have less influence on damage initiation and growth behavior than in edge-supported tests. However, it should be noted that damage resistance behavior observed using rigidly-backed specimens may not strictly translate to edge-supported applications. For example, sandwich constructions using cores with high compression stiffness or strength, or both (for example, balsa wood) may exhibit superior performance in rigidly-backed tests, but that performance may not strictly translate to edge-supported tests in which the core shear stiffness, core shear strength and sandwich panel flexural stiffness have greater influence upon the test results. Consequently, it is imperative to consider the intended assessment and structural application when selecting a test procedure for comparative purposes, and as such the use of Procedures B and C may be more appropriate for some applications. 5.3.3 For some structural applications, the use of a rigidly-backed specimen in drop-weight impact testing may be appropriate. Specific procedures for such testing are not included in this practice, but the general approach detailed for Procedure C may be useful as guidance material when conducting such assessments. Such tests should be performed in consideration of the implications of using rigidly-backed support conditions, such as their effect upon contact forces and sandwich deformation under impact, as well as the potential for damage to the test apparatus. 5.4 The standard indenter and impactor geometries have blunt, hemispherical tips. Historically, these tip geometries have generated a larger amount of internal damage for a given amount of external damage, when compared with that observed for similar indentations or impacts using sharp tips. Alternative indenter and impactor geometries may be appropriate depending upon the damage resistance characteristics being examined. For example, the use of sharp tip geometries may be appropriate for certain facing penetration resistance assessments. 5.5 Some testing organizations may desire to use these practices in conjunction with a subsequent damage tolerance test method (such as Test Method D8287/D8287M or Practice D8388/D8388M ) to assess the residual strength of specimens containing a specific damage state, such as a defined dent depth, damage geometry, damage location, and so forth. In this case, the testing organization should subject several specimens, or a large panel, to multiple indentations or impacts, or both, at various energy levels using these practices. A relationship between force or energy and the desired damage parameter can then be developed. Subsequent residual strength tests in accordance with Test Method D8287/D8287M or Practice D8388/D8388M can then be performed using specimens damaged using an interpolated energy or force level that is expected to produce the desired damage state.