ISO 18352:2009

Overview

ISO 18352:2009 specifies a standardized method for determining the residual compression strength-also known as compression-after-impact (CAI) strength-of multidirectional carbon-fibre-reinforced plastic (CFRP) laminates that have been subjected to impact damage. This International Standard, established by the International Organization for Standardization (ISO), is critical for the characterization and assessment of continuous-fibre-reinforced polymer matrix composite plates, particularly those manufactured from unidirectional prepreg tapes, fabrics, or woven fabrics.

The CAI test described in ISO 18352:2009 is designed to evaluate the compression performance of composite laminates after they have sustained damage from an out-of-plane impact at a specified energy level, a common scenario in aerospace, automotive, marine, and industrial applications. The data obtained from this method supports material specification, quality control, research and development, and the establishment of composite material databases.

Key Topics

• Compression-after-impact (CAI) test: A key component of this standard, the CAI test measures the residual compression strength of a composite specimen after it has been damaged by a controlled impact.

• Test specimens: The guideline covers the preparation, dimensions, and conditioning of test specimens-flat, rectangular CFRP laminate plates with multidirectional reinforcement.

• Impact procedure: Specifies the use of a drop-weight impact device with a hemispherical indenter at a defined energy level to simulate realistic impact damage.

• Non-destructive testing (NDT): Recommends the use of ultrasonic C-scan or equivalent techniques to detect delamination and characterize the extent of impact damage.

• Compression testing: Details procedures for mounting specimens in a compression fixture, instrumenting with strain gauges, and performing compressive loading while recording load-strain characteristics.

• Calculation and reporting: Instructs on calculating CAI strength, modulus, and maximum strain, and outlines essential information to be included in test reports.

Applications

ISO 18352:2009 is extensively used in industries where carbon-fibre-reinforced plastic laminates must perform reliably after low-velocity impacts. Typical application areas include:

• Aerospace engineering: For aircraft structural components where impact from tools or debris is possible, and residual strength is critical to flight safety.
• Automotive sector: For CFRP body parts and structural reinforcements that may encounter accidental impacts.
• Marine and energy industries: For composite components exposed to drops, collisions, or wave impact.
• Materials research and development: To evaluate the comparative damage tolerance of new or existing composite laminates.
• Quality control and specification: As a standardized method for certifying the impact resistance and post-impact integrity of composite materials.

By implementing ISO 18352:2009, organizations gain confidence that their materials meet international benchmarks for performance under impact loading, contributing to product durability, safety, and lifecycle cost optimization.

Related Standards

Adherence to ISO 18352:2009 is increased through integration with other relevant ISO standards, such as:

• ISO 291: Plastics - Standard atmospheres for conditioning and testing
• ISO 1268-4: Fibre-reinforced plastics - Methods of producing test plates - Part 4: Moulding of prepregs
• ISO 5893: Rubber and plastics test equipment - Specifications for tensile, flexural, and compression types
• ISO 14127: Carbon-fibre-reinforced composites - Determination of the resin, fibre, and void contents

Organizations working with CFRP and reinforced thermoset plastics benefit from referencing these standards for a comprehensive approach to specimen construction, conditioning, testing, and data reporting.

Keywords: ISO 18352, compression-after-impact, CAI test, carbon-fibre-reinforced plastics, CFRP, residual compression strength, composite laminates, impact-testing standards, non-destructive testing, polymer matrix composites, damage tolerance.