DeMattia Crack Growth Testing: Pierced VS Non-Pierced Methods

DeMattia crack-growth testing is a critical process for evaluating the durability and performance of rubber materials. This testing method assesses how rubber withstands repeated flexing, simulating real-world conditions to predict its longevity and reliability. Widely utilized in various industries, DeMattia crack-growth testing ensures that rubber products meet stringent quality standards and perform effectively over time.

DeMattia Crack-Growth Testing Defined

DeMattia crack-growth testing measures the resistance of rubber to crack initiation and propagation under repeated flexing. The test is performed using a DeMattia Crack Growth Tester, or MonTech FT 3000, which subjects rubber samples to continuous flexing cycles. The primary goal is to observe how cracks develop and grow in the material, providing insights into its fatigue resistance and durability.

ASTM Test Methods for DeMattia Crack-Growth Testing

The key standard for DeMattia Crack-Growth Testing is ASTM D813, of which accommodate two distinct testing methods: pierced and non-pierced samples.

Pierced Sample Testing

ASTM D813 specifies the procedure for testing rubber with an initial cut or notch (pierced sample). This method involves creating a small incision in the rubber sample before subjecting it to repeated flexing. Operator will be observing one crack. The primary purpose of this approach is to accelerate crack growth, providing a clear view of how pre-existing flaws in the material propagate under stress.

Non-Pierced Sample Testing

ASTM D813 also accommodates non-pierced samples, where the rubber specimen is tested without any initial cut or notch. This method evaluates the natural crack initiation and growth in the material. Likely, operators could see multiple cracks occurring. In this case, the result would be the summary length of all cracks, along with the number of cracks. By subjecting non-pierced samples to repeated flexing, this test offers insights into the inherent durability and resistance of rubber compounds without the influence of pre-existing defects.

Expected Differences in Results of Pierced Vs. Non-Pierced samples

The results from pierced and non-pierced sample testing can vary significantly, providing complementary information about the material's performance.

Pierced Samples

• Accelerated Crack Growth: The presence of an initial cut accelerates crack growth, offering a rapid assessment of the material's behavior under stress.
• Sensitivity to Flaws: This method highlights the material's vulnerability to existing defects, making it easier to identify potential weaknesses.
• Shorter Test Duration: Due to the accelerated crack propagation, the testing duration is generally shorter compared to non-pierced samples.

Non-Pierced Samples

• Natural Crack Initiation: Testing without an initial cut provides a more realistic evaluation of how cracks naturally initiate and grow in the material.
• Intrinsic Durability: This method reveals the material's intrinsic resistance to crack formation, offering a comprehensive view of its overall durability.
• Longer Test Duration: Since crack initiation is natural and not accelerated, the testing duration is typically longer, providing detailed insights into long-term performance.

Choosing the Right Method

DeMattia crack-growth testing, encompassing both pierced and non-pierced sample methods, is essential for understanding the fatigue resistance and durability of rubber materials. By adhering to ASTM standards, manufacturers can ensure their products meet high-quality benchmarks and perform reliably in real-world applications. Whether testing for accelerated crack growth or natural crack initiation, DeMattia testing remains a cornerstone of rubber material evaluation, driving advancements in quality and performance across industries.

MonTech's FT 3000 Rubber Fatigue and DeMattia Flex Tester is the perfect instrument for DeMattia testing, equipped with a CCD camera to monitor and record the progression of crack growth in test samples. To learn more about the FT 3000 Fatigue Tester, Click Here!