ASTM D790-17 rus PDF

Full title and description

ASTM D790-17 — Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials. This standard specifies three-point bending test procedures (Procedures A and B), definitions, calculations and reporting requirements for flexural stress, flexural strain, flexural modulus (tangent, secant and chord), and related measurements for rigid and semi-rigid plastic materials and electrical insulating materials.

Abstract

Provides test methods using a simply-supported beam with a midpoint load to determine flexural properties of solid rectangular specimens formed by molding or cutting from sheets, plates or shapes. The methods address specimen preparation and conditioning, deflection measurement (crosshead or deflectometer), calculation equations for stress and strain, limits (including a 5 % nominal outer-fiber strain limit for determining flexural strength) and guidance on when a four-point bend test (D6272) is more appropriate.

General information

• Status: Active (current edition D790-17).
• Publication date: July 2017 (approved/published July 2017; ASTM updates in July 2017).
• Publisher: ASTM International.
• ICS / categories: 29.035.20 (Plastics and rubber insulating materials).
• Edition / version: D790-17 (designation D790 — year 2017).
• Number of pages: 12 pages (official ASTM document length).

Scope

These test methods determine flexural properties (strength, stress at specified strain, flexural modulus, strain at yield, etc.) of unreinforced and reinforced plastics, including high-modulus composites and electrical insulating materials using a three-point loading system on a simply supported beam. The standard applies to solid, rectangular specimens and specifies specimen preparation, conditioning, deflection measurement options, span-to-depth considerations, and reporting requirements; it also notes that materials that do not fail within the 5.0 % outer-fiber strain limit may be better suited to a four-point bend test (D6272).

Key topics and requirements

• Three-point bending test configurations (Procedures A and B) and selection guidance.
• Specimen geometry and preparation: solid rectangular cross-sections, molding or cutting from plates/sheets/shapes.
• Deflection measurement methods: crosshead position or deflectometer and requirement to report which method was used.
• Calculation methods and key equations for flexural stress, flexural strain, tangent/secant/chord modulus.
• Limits and applicability: 5 % outer-fiber strain practical limit for flexural strength determination; span-to-depth ratio guidance to reduce shear effects.
• Reporting, units (SI preferred), conditioning and safety notes; cross-reference to related material specifications which take precedence when specified.

Typical use and users

Used by materials and plastics manufacturers, quality control and assurance laboratories, third-party testing laboratories, research and development teams, and standards bodies to characterize flexural properties for specification, acceptance testing and comparative evaluation of polymeric materials and insulating components. Test method selection and parameter reporting make it suitable for both production QC and research investigations.

Related standards

Related and cross-referenced standards include ASTM D6272 (four-point bending flexural test), ASTM D638 (tensile properties of plastics), ASTM D618 (conditioning of plastics for testing) and other ASTM material specifications; ISO 178 addresses flexural properties as well but is not technically equivalent.

Keywords

flexural properties, flexural strength, flexural modulus, three-point bend, plastics testing, electrical insulating materials, ASTM D790, Procedure A, Procedure B, deflectometer, crosshead, span-to-depth ratio.

FAQ

Q: What is this standard?

A: ASTM D790-17 is the ASTM International standard that defines test methods for determining flexural properties of unreinforced and reinforced plastics and electrical insulating materials using three-point bending.

Q: What does it cover?

A: It covers specimen preparation and conditioning, test procedures (Procedures A and B), measurement and calculation of flexural stress, strain and different moduli, deflection measurement options, limits of applicability (including a 5 % outer-fiber strain limit), and reporting requirements. It also advises when a four-point bend test (D6272) is preferable.

Q: Who typically uses it?

A: Materials manufacturers, product designers, QA/QC and testing laboratories, research groups and certification bodies use D790 for specification verification, comparative testing and quality control of plastic and insulating materials.

Q: Is it current or superseded?

A: The D790-17 edition is the active edition (published July 2017). Revision work items have been opened by ASTM to update the standard, indicating ongoing maintenance, but as of the current edition the D790-17 document remains the valid/active reference until formally superseded.

Q: Is it part of a series?

A: D790 is part of the ASTM suite of plastics test methods and is commonly cross-referenced with other mechanical-property methods (for example D6272 for four-point bending and D638 for tensile testing). It is managed by ASTM Committee D20 (Subcommittee D20.10).

Q: What are the key keywords?

A: Flexural strength, flexural modulus, three-point bend, Procedure A, Procedure B, deflectometer, crosshead, plastics testing, insulating materials.

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