ASTM D6790/D6790M-22

Overview

ASTM D6790/D6790M-22 is the internationally recognized standard test method for determining the Poisson’s ratio of honeycomb cores, widely used in sandwich panel construction. Developed by ASTM International, this standard provides a reliable methodology for measuring a critical material property when conventional test methods are inadequate. Characterizing the Poisson’s ratio of honeycomb core materials is essential for accurate structural design, material specification, research, development, and quality control in advanced composite applications.

Key Topics

• Purpose and Significance:

  • Addresses the need to determine Poisson’s ratio of honeycomb cores for analysis and design of sandwich structures.
  • Enables the assessment of core materials where direct measurement via traditional approaches is not feasible.

• Test Methodology:

  • Utilizes bending of honeycomb core specimens over a cylinder to generate anticlastic curvature, from which Poisson’s ratio is calculated.
  • Measurements involve standardized equipment, including accurately calibrated micrometers, calipers, a cylinder with a specified radius, scale, and straight edge.

• Influencing Factors:

  • Critical factors that must be reported and considered include:
    • Core material type and manufacturing process
    • Core and specimen geometry, including thickness and cell wall thickness
    • Preparation and conditioning of specimens
    • Environmental conditions during testing

• Reporting and Documentation:

  • Comprehensive reporting ensures traceability and repeatability, including specimen preparation, measurement details, calibration records, and environmental parameters.

Applications

ASTM D6790/D6790M-22 plays a vital role in industries that utilize sandwich composite structures, such as aerospace, automotive, marine, and construction. Typical applications include:

• Design and Engineering:

  • Supports accurate finite element analysis (FEA) and structural modeling by providing essential material properties of the honeycomb core.

• Material Specifications:

  • Assists material engineers in specifying core materials to meet mechanical requirements for performance and safety.

• Research and Development:

  • Facilitates comparison and evaluation of new or modified honeycomb core designs.
  • Enables investigation of the influence of fabrication techniques and material choices on core deformation characteristics.

• Quality Assurance:

  • Used for batch approval and production consistency by verifying that material behavior meets specified criteria.

Related Standards

For comprehensive evaluation of honeycomb core materials and sandwich composites, the following related ASTM standards are often referenced alongside D6790/D6790M-22:

• ASTM C271/C271M: Test Method for Density of Sandwich Core Materials
• ASTM D883: Terminology Relating to Plastics
• ASTM D3878: Terminology for Composite Materials
• ASTM D5229/D5229M: Test Method for Moisture Absorption Properties and Equilibrium Conditioning of Polymer Matrix Composite Materials
• ASTM E122: Practice for Calculating Sample Size to Estimate Average for a Lot or Process
• ASTM E177: Practice for Use of Terms Precision and Bias in ASTM Test Methods
• ASTM E456: Terminology Relating to Quality and Statistics

Using ASTM D6790/D6790M-22 in conjunction with these standards helps ensure that testing, analysis, and reporting around honeycomb core Poisson’s ratio are robust, compliant, and internationally harmonized.

Keywords: honeycomb core, Poisson’s ratio, composite sandwich panel, ASTM D6790/D6790M-22, test method, core material properties, structural materials testing, aerospace composites, material specifications, quality assurance.