Shock and random vibrations

Electronics that move is destined to experience a wide range of shock and vibration conditions. Every drop, pothole, landing and crash is a shock event. The rest of the time a device is in motion, it is been subjected to random vibrations.

The life of many modern electronics devices is dictated by it’s ability to handle shock and vib. Furthermore, finding a failure during shock and vib testing means weeks if not months of lost time in redesign, prototype and build.

 
 

Linear shock analysis

If you want an answer fast, then linear analysis is the way to go. There are 2 ways to do a linear shock analysis, response spectrum and modal superposition transient.

The method to use depends on the duration of the shock event, complexity of the assembly and frequencies of interest. Both method will provide fast results.

However this is linear so there is no contacts and soft materials need to be characterized carefully.

 

Non-linear shock analysis

Non-linear shock analysis is the most accurate way to simulate drop and shock events. It can also be done in 2 ways, implicit and explicit transient dynamics.

The path to choose depends on the device size and amount of deformation. Car and airplane crash will use explicit dynamics, mems devices, will use implicit. There is a wide gray area in between.

These simulation will predict the precise time history of shock and impact so it give the best information for these situations.

 

PCB assembly shock and vib

PCB assemblies are often the most sensitive components in electronics devices. DFR Sherlock is a great tool for simulating the reliability of a large PCB assembly because it greatly accelerate the setup process.

Moving the model from Sherlock to ANSYS allows engineers to add housing, stiffeners, brackets and other mechanical supports to make the model even more accurate.

The result can be brought back into Sherlock to calculate cycles to failure.