Keep it Simple

Abstract

Kirk and Fred discuss the challenge of using simple models for one finite element to extrapolate damage scalar metrics to very complex systems.

Key Points

Join Kirk and Fred as they discuss system models and how most fatigue damage models have many input variables, such as vibration and temperature, that can be very difficult to simultaneously measure across a system during operation

Topics include:

• The vibration response of a test unit can be very different depending on how it is coupled or mounted on a vibration table. This is why it should be held so that the unit under test is mechanically coupled with the same boundary (attachments) as in its end-use chassis
• Most new electronics systems are iterations of existing products with new capabilities and features. Instead of reviewing and modeling the entire system for reliability weaknesses, we should focus on the few subsystems or components that have the highest risk from our knowledge of predecessor products and the field warranty data.
• CAD and Multi-physics computer models can run useful simulations of vibration and fatigue damage in the design phase. When you get the first hardware prototypes, the real testing and discovery of mechanical or electrical weaknesses can be confirmed or dismissed. The more stress margin, the higher the probability of being a reliable product in the customer’s use.

Enjoy an episode of Speaking of Reliability. Where you can join friends as they discuss reliability topics. Join us as we discuss topics ranging from design for reliability techniques to field data analysis approaches.

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Show Notes

Please click on this link to access a relatively new analysis of traditional reliability prediction methods article from the US ARMY and CALCE titled  “Reliability Prediction – Continued Reliance on a Misleading Approach”. It is in the public domain, so please distribute freely. Attempting to predict reliability  is a misleading and costly approach to use for developing a reliable system.

You can now purchase the most recent recording of Kirk Gray’s Hobbs Engineering 8 (two 4 hour sessions) hour Webinar “Rapid and Robust Reliability Development 2022 HALT & HASS Methodologies Online Seminar” from this link.

For more information on the newest discovery testing methodology here is a link to the book “Next Generation HALT and HASS: Robust design of Electronics and Systems” written by Kirk Gray and John Paschkewitz.

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