Proof Load Testing - Clark Testing

Proof Load Testing


A proof load test is a type of non-destructive test where the component is loaded to a determined load and held there in order to verify that the component can withstand the load. The load requirement is usually two to six times the normal operating load, and the failure criteria usually include cracking or deformation of the part. Proof testing can verify the maximum load safety factor is being met and help meet other quality and safety specifications.

Proof load testing is often a requirement in the aerospace and defense industries that need to ensure that every part in an assembly is certified to meet certain load requirements. Sometimes every part will need to be tested, or several samples out of each batch of parts. With our calibrated instruments traceable to NIST and ISO 17025:2017 quality program Clark Testing is ready to perform the proof load tests needed to qualify your parts for use.

Clark Custom Designed Testing


Clark Testing specializes in designing custom test setups based on our customer’s needs. We have the capability to design control systems to apply multiple loads based on custom load profiles while recording data on any number of channels needed. Our design engineers can work with your CAD model and our FEA software to design frames and fixtures for your testing to ensure that the test can be conducted under circumstances that are as close to field conditions as possible.

Clark Fatigue Load Testing Capabilities


  • Vertical and horizontal load frames with 55,000 lb, 100,000lb and 1,000,000+ lb capabilities
  • Data acquisition on dozens of channels at rates up to the mhz range
  • Strain gage application and data recording
  • Displacement or elongation measurement
  • Servohydraulic controlled actuators to apply loads

Clark Test Report


Clark’s test reports adhere to the quality requirements of ISO 17025:2017 and will include.
  • An overview and summary of the testing performed
  • A detailed list of the setup and NIST-traceable instruments that were used
  • The test method used
  • Test results; including load vs time, data tables, comments and observations from the test
  • Photographs of the test setup and the parts for failure analysis
Proof load testing often has certain common results that are recorded, such as.
  • Load vs time
  • Max Load
  • Deflection at max load
  • Permanent deflection after test
  • Elongation
  • Strain measurement with strain gauges.
  • Crack initiation through dye penetrant or magnetic particle inspection




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Clark Testing has been providing product qualification testing and design verification for manufactures for over 20 years. We provide our clients with independent testing.

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Clark Testing continuously operates under stringent quality assurance guidelines ensure all policies, practices and procedures meet or exceed industry standards. Clark’s QA/QC programs follow the accreditation guidelines of ISO 17025-2017, 10CFR50 Appendix B, NQA-1 and AIHA.

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