Vibration Control

Introduction

"In 1996 I started my first job as a graduate engineer at an engineering consultancy firm - LGI, in Pretoria, managed by professors and lecturers of the University of Pretoria. It was at this company that I was introduced to vibration control of complex problems.

I then developed an interest in vibration and the consequences of extensive vibration levels." - Paul Schmitz MBA CEng, Director of Environmentally Sound Limited

Vibration Control Engineering

Environmentally Sound Limited is an acoustic and mechanical engineering consultancy that resolves noise and vibration problems.

To solve vibration problems, we first understand the problem by modelling the behaviour using measured vibration data and then update the analytical model to get the desired structural dynamics for more favourable vibration.

This is a method used to achieve more favourable vibration levels. Another method is Vibration Isolation, in which we provide passive vibration isolation solutions.

Vibration Control vs Vibration Isolation

Vibration isolation is a mechanism to isolate the vibration from propagating further into the structure or neighbouring structures, by typically using isolation mounts or anti-vibration mounts.

For this mechanism to be effective, the operating frequency must be more than three or greater times than that of the resonance frequency of the mass on the isolation mounts, for the isoaltion to be effective.

The effectiveness of the isolation is also dependent on the damping of the mount.

What if the operating frequency changes, is not fixed and it is not possible to specify an isolation mount?

This is the case for many vibration environments, like on an aircraft, where vibration testing for certification is broadband from 10Hz to 2000Hz. This is when vibration control is the only option. Vibration can be mitigated by design optimisation, manipulating mode shapes by design etc.

Let's discuss a case study. This case study is of a fabricated electronic distribution box that was developed for Dassault Aviation's Falcon 7X.

Dassault Aviation did not permit vibration mounts (as the rubber degrades over time, and is not strong enough for crash safety) or air movers (fans for cooling the electronics) in their aircraft equipment.

…and the greatest challenge, to keep the weight down, as the lighter the plane, the cheaper the operating cost.

So vibration control was the only option.

The box was engineered to sustain the brunt of the aircraft vibration, by optimising the design of the box, i.e. the printed circuit boards (PCB) were structurally optimised to mitigate the vibration levels to which the electronic components were subjected.

The positioning of the stand-off pillars (between the box base and the PCBS) were placed strategically to avoid the high vibration areas of the base of the box.

Vibration testing was the proof that vibration control engineering was effective.

How can we help you?

As Environmentally Sound, we can help with the design of products that are subjected to unfavourable vibration levels by vibration control engineering - making them resilient and robust to the vibration environment.

Furthermore, we can also mitigate the vibration of a structure by design optimisation.

Further information

If you require assistance with designing equipment or machinery subjected to vibration, please call us and speak to a vibration control engineer, we are very forthcoming and helpful.

We are adding our case studies to this website over the next month onwards, so please return to see what other work we've completed.