Fatigue Testing


Fatigue Testing

Our substantial on-site capabilities allow us to customize each project. We design and write our own proprietary software to control and analyze your test results. To ensure the best turnaround time on your projects, we design and machine our own specialized fixtures. For unique testing needs we have the people, resources, experience, and testing capacity to get the job done right for you.

We are specialists in conducting axial tests on many different types of specimens. These tests are conducted in load, strain, or position control on servo-hydraulic test equipment at temperatures ranging from Liquid Helium to over 2000°F. We have the flexibility and resources to accommodate a wide range of sample sizes with our machine capacity ranging from 25 Grams to 1,000,000 lbs.

For example, WMT&R is an industry leader in Low Cycle Fatigue (LCF) Testing. This test is normally run in strain control with the load being a dependent variable. The strain variables that are usually defined by the customer are: wave type, frequency (and hold time for a trapezoidal wave), mean strain, strain amplitude, and discontinue cycles. There are three stages to low cycle fatigue testing. The first stage is designed to detect crack initiation on a polished specimen. The second stage is propagation life, which occurs after initiation. The third stage is failure, which is usually determined by some percentage of load drop from a stable condition. Data reported on this test includes load peaks, strain peaks, hysteresis loops at specific intervals, calculated plastic and elastic strain, first cycle information, and half-life cycle loop information.

In addition to axial tests, we also test materials in bending and rotating modes. Bending fatigues could involve three or four-point flexural tests or cantilever fatigue tests. Rotating beam fatigues are commonly done and are available at room or elevated temperatures. Machining samples from exotic or difficult material is no problem for our in-house machine shop.

Do you have need of testing on full-size components or assemblies? We have designed and executed tests on railroad locomotive suspension springs, automotive components, aircraft supports, helicopter rotor blades, coal mining equipment, and artificial hip stems to name a few.

Artificial hip stems are tested for a variety of discerning manufacturers. WMT&R has extensive experience in conducting two of the most common types of artificial hip fatigue testing - the three point bend and the distally potted hip method per ISO specification 7206-4 or the ASTM F1440-92 specification. In our fatigue lab, it is possible to simulate 5 years of normal use in only six days! This data is used to improve the quality of the implants, which improves the quality of life for the recipients.

Another area that directly relates to people's lives is Fastener Testing, because the failure of a fastener can have catastrophic consequences. Every minute of every day all of us rely on fasteners in our cars, homes, and places of work. Our Fatigue Department is involved with a diverse array of fastener tests such as: fatigue, tensile, wedge tensile, double shear, stress rupture, stress durability, microstructure and chemical analysis. WMT&R meet all the requirements of the Fastener Quality Act (FQA) and its Amendments. For more information concerning the FQA, click here.

To achieve the best in performance, all of our tests may be run under computer data acquisition. This allows us to obtain data on how a material changes in response to fatigue loading. This data is available to you typically in a tabular data summary and as graphical representations. Additionally, raw data can be provided on floppy disks, CDs, or securely transferred across the Internet from our FTP site. Due to the nature of fatigue testing, it is positively necessary to keep you informed as to the status of your testing. We work closely with our customers using voice, fax, and electronic communication to ensure they are kept current and in the loop.