Commissioning a vibration testing laboratory: what a shaker table actually reproduces and what it cannot, why the fixture is part of the test, and what a battery testing laboratory adds in safety containment when the same sample is then abused

Commissioning the work

1. Name the profile, the axes and the duration. A random vibration profile, a sine sweep or a shock pulse are different tests, and the level, the frequency range, the duration and which axes are driven all have to be stated. A request to vibration test something is not a specification.
2. Treat the fixture as part of the test. The fixture couples the shaker to the specimen and its own resonances will either amplify or absorb the input. A fixture designed to be stiff through the test frequency range, with control accelerometers placed as the standard requires, is what makes the input the specimen sees the input you asked for.
3. Decide what constitutes a failure before the test. Visible damage, loss of function, an intermittent connection during the test, or a change in a resonance survey before and after. Deciding afterwards is deciding with a result in front of you, and a resonance survey either side is the most informative comparison available.
4. For batteries, establish the containment and the safety case first. Abuse testing deliberately drives cells to failure, so the laboratory needs a containment chamber, gas handling, fire suppression and people trained for a thermal runaway. Ask to see the facility rather than reading about it.
5. Check the accreditation scope covers the exact test. Accreditation is granted for specific standards over specific ranges and axes, and transport testing in particular is governed by specific regulations. A laboratory accredited for one standard is not thereby accredited for the one your product needs.

Combining vibration with temperature

Many service environments are hot or cold as well as vibrating, and a combined chamber tests both together. Failures that appear only under combined loading are common and are exactly what a sequential test misses.

Combined testing costs more and fewer laboratories offer it, so confirm capability and the chamber's size against your specimen early rather than at booking.

What the report should contain

The profile as demanded and as achieved, control and monitoring accelerometer positions and traces, the fixture description, resonance surveys before and after, and photographs. A report with a pass statement and no traces is not reviewable.

Ask for the raw data as well as the document. Reconstructing a spectrum from a printed plot is impossible and it is what somebody will want in a year.

Transport and shipping tests

Shipping tests are a distinct family with their own standards, covering drop, compression and the vibration of a vehicle. For batteries, transport testing is a regulatory requirement rather than a design exercise.

Ask the laboratory which regulation applies to your product and in which markets. Getting that wrong is discovered at a border rather than in a report.

Common questions

What has to be specified for vibration testing?

The standard or profile, the level and frequency range, the duration, which axes are driven, the mounting and the pass criteria. Without those, two laboratories will run different tests and both will be correct.

Why does the fixture matter so much?

Because it sits between the shaker and the specimen and has its own resonances. A poor fixture amplifies some frequencies and absorbs others, so the specimen never sees the specified input and the test proves nothing.

What does a battery testing laboratory need that others do not?

Containment chambers, gas extraction, fire suppression and staff trained for thermal runaway, because abuse testing deliberately causes failure. For transport testing, accreditation to the specific regulations that govern shipping cells.

Should the product be tested functioning?

Where it is functioning in service, yes, with monitoring during the test. Intermittent faults that appear only under vibration are exactly what the test exists to find and are invisible in a post-test inspection.

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