What is the Purpose of Fatigue Testing?
Fatigue testing is a valuable tool for predicting how a material will react to repeat distortions and when it might crack or rupture while in service. Testing experts can simulate an accelerated life cycle in a laboratory to observe the long-term effects of stress and strain in a shortened period of time.
Flex fatigue testing can be used to demonstrate regulatory compliance and support research and development products. For example, manufacturers may use fatigue testing data to determine which material or iteration of a compound has greater endurance.
Types of Rubber Fatigue Tests
ASTM D430—Standard Test Methods for Rubber Deterioration—Dynamic Fatigue
Many rubber products are subjected to repeat distortions while in service. This may include extension, compression, bending, or a combination of forces. Repeat distortion can weaken rubber materials over time, causing ruptures or cracks in the surface.
ASTM D430 is a standardized test method for observing and measuring the effects of repeat distortion on a rubber material sample. ASTM D430 is conducted using a flexing machine in a controlled laboratory environment.
ASTM D430 is suitable for both pure rubber and rubber combined with other materials, such as fabrics or cording. This makes ASTM D430 an incredibly valuable test procedure for the tire industry. The average passenger car tire contains at least 50 raw materials, including textile reinforcements that must adhere to the tire’s rubber components. The methods detailed in ASTM D430 are designed to account for both rubber breakage and adhesion failure as equally significant outcomes of testing. ASTM D430 is also used to test belts, footwear, and molded goods.
ASTM D813—Standard Test Method for Rubber Deterioration—Crack Growth
Even the smallest cracks and cuts in a rubber product can grow dramatically over time, resulting in performance issues and product failure. Crack growth can be inhibited through the addition of certain plasticizers and other materials to the compound formulation, but materials must still be tested.
ASTM D813 was designed to observe and measure a rubber material’s ability to resist crack growth by subjecting the sample to bending and flexing in a controlled environment. The sample is pierced in a specified location, clamped into the flexing machine, and subjected to a prescribed number of flexing cycles. The growth of the pierced area is observed and measured over time.
ASTM D813 has many applications but is especially important for testing synthetic rubber materials. Some synthetic rubbers are resistant to other types of flex fatigue testing but vulnerable to forces replicated by ASTM D813, making ASTM D813 a vital element of any flex fatigue testing program for synthetic rubber compounds.
ASTM D4482—Standard Test Method for Rubber Property—Extension Cycling Fatigue
Unlike other flex fatigue tests, ASTM D4482 is conducted on a whole sample without any cuts or punctures. Samples are strained and relaxed at prescribed intervals to replicate a tensile strain cycle in service. The purpose of the test is to help manufacturers predict when a crack or other imperfection may appear in the material while in service.
ASTM D4482 is most commonly used to test materials destined for use in tires.
Ensure Quality Rubber Performance
ACE Laboratories is dedicated to offering comprehensive fatigue testing services and the fastest turn-around times in the industry. We recently expanded our rubber fatigue capabilities with a new, state-of-the-art testing machine with a built-in environmental chamber, so we can offer flex fatigue testing at different temperatures. Whether you’re testing to ASTM flex fatigue standards, benchmarking rubber materials, or working on an R&D program, you can count on ACE to get you the testing data you need to keep your project on track.
To learn more about flex fatigue testing from ACE, get in touch.