Reliability Services in the Design Phase
Dynamic Analysis (modal, shock, vibration)

DEFINITION
Dynamic Analysis is the process of:
1) measuring the mass and damping effects of a structure;
2) applying explicit dynamics to a large deformation simulations where inertia forces are dominant; and
3) simulating impact, crashing and rapid forming.

SITUATION
We often uncover vibration/shock issues too late in the development cycle. Proper Dynamic Analysis early in the design can pinpoint some of these issues before the design is complete.

Also, when a vibration/shock issue is discovered during testing, we need proper troubleshooting tools to determine root cause. Dynamic Analysis is a great tool in this situation.

OBJECTIVES
To understand vibration/shock issues prior to the completion of the design and to have a method for troubleshooting and input to a redesign after a vibration/shock issue is found.

VALUE TO YOUR ORGANIZATION
Some of the benefits of Dynamic Analysis are that it:

1) allows engineers to calculate natural frequencies and mode shapes;

2) allows engineers to determine a structure's response to sinusoidal loads of known amplitude and frequency; and

3) allows engineers to determine a structure's response to time-varying loads and can include non-linear behavior.

RELIABILITY INTEGRATION
An example of Reliability Integration during Dynamic Analysis is as follows:

HALT May Find an Issue that Requires Dynamic Analysis to Solve
After a vibration issue is uncovered during HALT, we need to analyze the cause of the failure and provide corrective action. Dynamic Analysis is the perfect vehicle for doing this.

METHODOLOGY
In a Dynamic Analysis, we use computer models and simulations to:

1) measure the mass and damping effects of a structure;

2) apply explicit dynamics to a large deformation simulations where inertia forces are dominant; and

3) simulate impact, crashing and rapid forming.

CASE STUDIES/OPTIONS
The following case studies and options provide example approaches. We shall tailor our approach to meet your specific situation.

1) Dynamic Analysis Used to Analyze a HALT Failure
During a HALT for a Networking company, we discovered that a component was breaking off due to flexing of the board during vibration. The immediate thought was to reduce the flexing by adding a board stiffener near the area of high flex. We decided to run a Dynamic Analysis on the board and found that if we placed a board stiffener in that location, we would have solved this issue but cause several more issues due to new resonances. The result of the Dynamic Analysis model showed us that indeed a board stiffener was the right answer, but about 2" from the location we were originally considering.

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