ASTM D8388/D8388M-22 PDF
Standard Practice for Flexural Residual Strength Testing of Damaged Sandwich Constructions
Standard Practice for Flexural Residual Strength Testing of Damaged Sandwich Constructions
- Статус документа:
- Действующий
- Формат:
- Электронный (PDF)
- Количество страниц:
- 7
- Дата публикации:
- 1 мая 2022 г.
- Издание:
- D8388/D8388M
- ICS:
- 91.080.99
SIGNIFICANCE AND USE 5.1 This practice provides supplemental instructions that allow the use of Test Method D7249/D7249M to determine residual compressive or tensile strength properties of damaged 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 residual strength properties of a sandwich panel is useful for product development, establishing design allowables, and material selection. 5.2 The residual compressive or tensile strength data obtained using this test practice is most commonly used in material selection, research and development activities, and establishing design allowables. 5.3 The properties obtained using this test practice can provide guidance in regard to the anticipated compressive or tensile residual strength capability of sandwich constructions of similar facesheet and core material, adhesive, facesheet and core thickness, facesheet stacking sequence, and so forth. However, it must be understood that the residual strength of sandwich constructions is highly dependent upon several factors including geometry, thickness, stiffness, support conditions, and so forth. Significant differences in the relationships between the damage state and the residual compressive or tensile strength can result due to differences in these parameters. 5.4 The compression strength from this test may not be equivalent to the compression strength of sandwich structures subjected to pure edgewise (in-plane) compression. 5.5 The reporting section requires items that tend to influence residual strength to be reported; these include the following: facesheet and core materials, core density, cell size and wall thickness if applicable, film adhesive, methods of material fabrication, accuracy of lay-up orientation, facesheet stacking sequence and thickness, core thickness, overall specimen thickness, specimen geometry, specimen preparation, specim... SCOPE 1.1 This practice provides instructions for modifying the long beam flexure test method to determine the tensile or compressive residual strength properties of sandwich constructions that have been subjected to quasi-static indentation or drop-weight impact per Practice D7766/D7766M. The tensile or compressive strength result is determined by which facesheet contains the damage, either the loaded-span or support-span facesheet, based on how the specimen is positioned in the fixture. 1.2 This practice supplements Test Method D7249/D7249M with provisions for testing damaged sandwich specimens. Several important test specimen parameters (for example, facesheet 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 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. 1.3.1 Within the text, the inch-pound units are shown in brackets. 1.4 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. 1.5 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.
Abstract
Overview
ASTM D8388/D8388M-22: Standard Practice for Flexural Residual Strength Testing of Damaged Sandwich Constructions provides comprehensive instructions for assessing the residual tensile or compressive strength of sandwich panels after they have been damaged. Developed by ASTM International, this standard extends the long beam flexure test method, enabling materials engineers and designers to evaluate the structural integrity of sandwich constructions following quasi-static indentation or drop-weight impact.
Sandwich structures-commonly featuring a lightweight core between strong facesheets-are widely used in aerospace, automotive, marine, and construction industries due to their high strength-to-weight ratio. Ensuring continued performance after localized damage from out-of-plane forces is a critical design consideration. This standard supplies practical methods to quantify the residual strength of such constructions, supporting effective product development and informed material selection.
Key Topics
- Residual Strength Evaluation: Outlines procedures for measuring compressive and tensile strength of sandwich composites post-damage, following modifications to the long beam flexure test.
- Damage Simulation: Covers imparting damage using quasi-static indentation or drop-weight impact, as per ASTM D7766/D7766M.
- Specimen Handling: Addresses critical factors in specimen preparation, geometry, and alignment to ensure meaningful, repeatable test results.
- Reporting Requirements: Details essential reporting items, such as facesheet and core material properties, geometry, fabrication method, and precise test configurations that influence residual strength outcomes.
- Influencing Factors: Notes that results are highly dependent on construction geometry, facesheet stacking, core thickness/density, support conditions, and environmental exposure.
- Failure Mode Classification: Provides guidance for identifying and reporting failure modes, ensuring clarity and consistency in residual strength testing.
- Units of Measure: Permits use of both SI and inch-pound units, with specific guidance to avoid mixing unit systems in data collection and reporting.
Applications
The methodologies in ASTM D8388/D8388M-22 are used extensively in the following contexts:
- Product Development: Enables manufacturers and engineers to assess how sandwich panels perform after suffering typical service damage, aiding in the refinement of composite designs.
- Material Selection: Supports comparative evaluation of different facesheet and core combinations, adhesives, and manufacturing processes under realistic damage scenarios.
- Research and Development: Provides a reliable framework for collecting quantitative residual strength data, essential for innovation in composite materials engineering.
- Design Allowables Establishment: Assists in determining conservative values for residual compressive or tensile strength, influencing permissible loading conditions in structural designs.
- Damage Tolerance Certification: Supports validation that sandwich constructions meet industry safety and reliability standards, particularly in regulated sectors like aerospace.
Related Standards
- ASTM D7249/D7249M: Test Method for Facesheet Properties of Sandwich Constructions by Long Beam Flexure - the foundational test method supplemented by D8388/D8388M for damaged specimens.
- ASTM D7766/D7766M: Practice for Damage Resistance Testing of Sandwich Constructions - referenced for imparting controlled damage prior to residual strength assessment.
- ASTM D3410/D3410M: Test Method for Compressive Properties of Polymer Matrix Composite Materials - informs compressive test procedures.
- ASTM D5687/D5687M: Guide for Preparation of Flat Composite Panels - essential for recommended specimen preparation practices.
- Terminology Standards: Includes ASTM D3878 (composite materials), D883 (plastics), E6 (mechanical testing), and E456/E177 (statistics and quality terms).
Practical Value
Implementing ASTM D8388/D8388M-22 helps organizations:
- Quantify the real-world performance of sandwich structures after damage
- Improve safety and reliability in lightweight composite applications
- Standardize testing protocols, facilitating data comparison across materials and products
- Support compliance with industry regulations and international standardization requirements
Keywords: sandwich construction, residual strength, flexural testing, compressive strength, tensile strength, composites, damage tolerance, ASTM D8388/D8388M, quasi-static indentation, drop-weight impact, material selection, structural testing.
Технические детали
- Технический комитет
- D30 - Composite Materials
- SKU
- ASTM D8388/D8388M-22
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