TRaC help to HALT reliability problems on military vehicles

Confidence in product reliability, above and beyond meeting conventional "qualification testing" is becoming increasingly more demanding across defence land systems.

As product designs evolve through functional enhancements or obsolescence, accelerated life testing plays an increasingly important role in assuring reliability where conventional field proven data does not exist.

As part of an on-going series of technical training seminars, TRaC hosted a successful HALT (Highly Accelerated Life Testing) and HASS (Highly Accelerated Stress Screening) training day to a wide section of the defence land system community in May, ranging from the MOD, prime contractors through to LRU manufacturers.

"HALT/HASS technical seminar held at TRaC Warwick, May 2010" (right)

As a reliability tool, HALT is rapidly emerging in military land systems as a recognised means to dramatically cut equipment development timescales through a process of accelerated aging. This

is achieved by employing high levels of multi-axial vibration and rapid temperature cycling, either separately or in combination. Whilst the test does not mimic a particular reality, it very effectively employs environmental conditions commonly experienced in service, and so exposes design features and manufacturing defects which could lead to premature failure.

 

The day's events, including practical hands on testing, provided delegates with a good understanding of the complementary use of HALT and HASS techniques, the fit within the bigger picture of reliability assurance, and an appreciation of how to apply these techniques to their own products.

The day's events also drew upon the alternative approach of reliability validation through computer simulation using Finite Element Analysis techniques. Whereas HALT is an excellent tool for assessing the reliability of electronics when prototype test specimens are available, it is often the case in military vehicle development that prototypes are:

1. unavailable to test and break due to their high value
2. primarily mechanical in nature and thus not well suited to HALT
3. larger in size than can be accommodated on conventional testing equipment

"FEA techniques to validate product reliability against vibration in its in service environment"  (right)

Combining TRaC's physical test and stress analysis expertise, TRaC can capture real world in-service vibration...Read the full article