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Forensic Engineering and Failure Analysis
Failure Analysis Engineering - Application of All Engineering Disciplines in the Investigation of Distress and Failure in Engineered Systems.
Forensic Engineering - Specialized Services as Consultants to Members of the Legal Profession and as Expert Witnesses in Courts of Law, Arbitration and Administrative Proceedings. CIVIL STRUCTURES CATASTROPHIC FAILURE DURING CONSTRUCTION, POST TENSIONED BRIDGE ANCHORAGE
Typical Post Tensioned Anchorage, BEFORE
After application of tension, failed Anchorage
Examples from the Finite Element Models of the Failure Mechanism
MECHANICAL SYSTEMS Vibration Equipment, Stainless Steel Weldment Failure Mechanism - Fatigue Cracks at Fillet Welds
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Photographs of failed machine showing primary and secondary failure initiation locations (failure mechanism is the same)
Examples from the Finite Element Dynamic model used to investigate the failure (Modal and Time History
For an automatic POWER POINT slide sequence (900 kb) of the cyclic stresses that caused fatigue crack initiation, right click HERE and "save as" to a directory.
SPECIAL STRUCTURES: LARGE SCALE WATER FEATURE The design of some structures involve several engineering disciplines. When these structures fail, the failure mechanism is usually also multi- disciplinary.
In this case, a large scale water feature was built using large Limestone blocks interlocked horizontally and attached to a concrete substrate. The wall was 350 feet long, consisting of a straight and curved section. The height increased from 6 to 16 feet tall. Environmental conditions were severe, subject to wide seasonal variation in temperature and moisture.
The wall was designed without expansion joints...
Following the first failure event, the original defective design was not detected. The water feature was, therefore, rebuilt...again without expansion joints.
When a second failure occurred, the owners decided to have both failures investigated prior to attempting a second reconstruction project.
Clear evidence of seasonal expansion and contraction, due to thermal and moisture effects, was identified in the original failure event. The same mechanism was responsible for the second failure.
Extensive Finite Element Modeling of the failure mechanism, involving non-linear formulation and Mechanical Event Simulation, was used to investigate the original defective design. These FEA models were then used to evaluate changes to original design.
Click HERE for a time lapsed animation of the initial failure mechanism (1.6 Mb file - allow for download time; Best with Windows Media Player on large scale)
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