Mechanical Failure Analysis

Exponent’s mechanical failure analysis capabilities hearken back to the founding of the firm and the pioneering contributions of our two main founders, Dr. Bernard Ross and Dr. Alan Tetelman. Our range of mechanical failure analysis services extend far beyond handbook machine design calculations and linear fracture mechanics of metal structures to include computer modeling of highly complex materials, structures, and machines; nonlinear fracture mechanics; advanced laboratory testing capabilities; higher-level systems analysis; and “big data.” Despite the advances in mathematical, computational, and laboratory tools, the proven failure analysis approach employed by our founders and their fellow mechanical engineers remains the same:  to apply the scientific method rigorously by gathering facts, posing hypotheses, testing the hypotheses against the evidence to discover the cause of failure, and communicating the results effectively to a wide range of audiences.

Exponent approaches mechanical failure analyses rigorously and systematically, while avoiding myopia that can be caused by rigid adherence to common failure analysis tools such as fishbone diagrams and “5-Whys.”

Modern complex mechanical systems are often highly computerized and instrumented, such that massive amounts of data are recorded for every minute of operation of a large machine or plant. When failures occur, this data often contains important clues about the cause of failure. Exponent has the expertise, software, and computing power to sift massive databases for data relevant to a failure, analyze the data, and communicate complex results so that they are readily understood. Exponent has applied these techniques to failures of large power generation equipment, tunnel boring machines, and ore processing plants. In each instance, the analysis proved invaluable in determining the cause of a failure.

Mechanical failure is often due to fracture of a part of the system. To understand failures involving fracture, Exponent applies state-of-the-art linear and nonlinear fracture mechanics and damage mechanics. Our staff includes engineers and scientists who have published on the analysis of brittle and ductile fracture in metals, plastics, ceramics, biological, and composite materials. We analyze fracture surfaces macroscopically and microscopically, we calculate J-integral crack driving forces, and measure crack growth resistance in the laboratory as we seek the causes of mechanical failure. We apply cyclic loads to induce fatigue fracture in the laboratory using servo-hydraulic, electronic, mechanical, and vibratory testing machines, in order to replicate failures that have occurred and prevent others.

Exponent has multiple staff specializing in complex computer-based finite element analysis of mechanical failures. We apply ABAQUS, ANSYS, and COMSOL among powerful software tools, and run them on a robust computer cluster to provide high throughput and the ability to handle large, highly detailed models of complex industrial, medical, and consumer product mechanical failures.

Many failures that are ostensibly mechanical may actually involve non-mechanical issues. The breadth of disciplines available at Exponent allows the appropriate expertise from almost every engineering and scientific discipline to be applied to solve a client’s failure problem. For example, when we encounter failure of high-pressure metal-reinforced rubber hoses, we are able to draw upon specialists in mechanical failure analysis, metallurgy, polymer sciences, and X-ray computed tomography (CT) scanning to find the cause.

Services


  • Failure analysis of mechanical systems, mechanisms, machinery, gears, bearings, shafts, pressure vessels, piping, valves, and fittings.
  • Linear and nonlinear computer finite element analysis of structures ranging in scale from microelectronic chips to giant earthmovers, and involving complex contact, thermal stresses, and fluid-structure interaction.
  • Remaining life and fitness-for-service evaluation of structures, machinery, and process equipment undergoing fatigue.
  • Planning and execution of mechanical testing programs to validate the failure resistance of new designs.
  • Rapid-response, world-wide, on-site failure analysis of critical manufacturing production facilities.
  • Reconstruction of failures and accidents involving industrial machinery and construction equipment.
  • Planning and execution of large scale field investigations of mechanical failures, including photography, 3D scanning, surveying, and evidence documentation, collection, and preservation.
  • Measurement of mode shapes, frequencies, and damping characteristics of vibrating equipment and structures.
  • Surveys of mechanically damaged equipment to determine the extent of failure, reparability, and salvage value.
  • Assessment of the risk of multiple product failures when a family of products shares a common flaw or is subject to misuse.

Professionals