We were tasked with performing fatigue testing on eight off bolts from three separate batches, to determine how many cycles of fatigue the samples could withstand before failure.
Our customer specified that their minimum requirements for the sample to pass the test was 45,000 cycles for each individual bolt without fracture or failure, and the maximum would need to be 130,000 cycles. Each batch of bolts required a minimum of 2 bolts to be tested, and an average of 65,000 cycles to be performed.
Bespoke fixtures were needed to hold the sample in place to conduct the testing. Due to the frequencies of the tests that needed to be carried out, the bespoke fixtures would need to be changed between every 10-15 tests.
How We Supported
Using our inhouse 250kN hydraulic test machine (Vienna), we performed fatigue testing on four off bolts from the first batch.
The test was carried out at ambient temperature, with loads ranging from 13kN to 142kN in accordance with the customer’s requirements.
The results showed that the four bolts did not have any fractures or failures after the maximum of 130,000 cycles.
We then performed the same fatigue test parameters on the rest of bolts, from two different batches.
The results showed that these bolts were more susceptible to failure; three of the bolts in these tests were able to achieve the minimum cycle rate of 45,000 tests before fracturing in the thread of the bolt. The fourth bolt experienced failure at approximately 38,000 cycles, therefore it did not pass the requirements.
Verifying Fasteners is a Crucial Element of the Manufacturing Process
Fasteners such as bolts, head screws, nuts and studs are a crucial element of any structure, as they provide strength, durability and structural integrity for holding other materials and components together.
John Cross, General Manager at Phoenix Materials Testing says, “These fixtures couple other materials together, and if they fail, they are the weak link in the assembly. Verifying they are fit for function is critical.
“If expert verification is not conducted, we have products that cause catastrophic health and safety issues, failed parts causing oil spills and sunken ships, with devastating environmental, human and economic impact.”
Without appropriate testing to understand how they will perform in real-service conditions, there is an increased risk for health and safety, quality compliance and even legal implications if fasteners were to fail.
We work with many fastener manufacturers, both nationally and globally to provide fatigue testing on large bolts up to size M42 to verify if a customer’s product is fit for purpose.
Christophe Welzel, Quality Manager for Heinrich Jungeblodt says, “Compromising quality is not an option. Measurement and checking processes are essential for our production procedures, so we sub-contracted fatigue testing on our samples to Phoenix for additional verification and quality control checks.
It is crucial that we are very precise when checking the stress that our samples can withstand, and Phoenix worked with us to develop a contract review and testing programme that was suitable for our needs.
We were recommended to Phoenix by a mutual contact, as they had a great experience for their own similar testing needs.
We have found the service from Phoenix to be very communicative, they have kept us up to date with the progress of the tests and results, and overall, we have been very happy with our experience. We look forward to working with Phoenix again in the future.”
