Mechanical shock testing reproduces the transient high loads of potholes, speed bumps and tyre burst. Unlike the sustained excitation of vibration, shock is a short high-acceleration event and is more likely to cause structural damage and connection failure.
Test types
Half-sine pulse: the most common shock waveform; acceleration rises and then returns to zero following a sine curve.
Trapezoidal pulse: acceleration holds at peak for a set time and then returns to zero, approximating square-wave behaviour.
Shock direction: determined by the product mounting state; usually all three axes X/Y/Z must be covered.
Typical transient events
Wheel hop: relative motion between wheel and body as the vehicle passes a pothole at speed.
Speed bump impact: a routine road condition, set by vehicle speed and bump height.
Tyre burst: the strong transient produced when a tyre suddenly fails while driving.
Engine ignition transient: the electromagnetic and vibration transient produced by the ignition system.
Handling shock: drops and impacts during production, storage and transport.
Common failure modes
Connector fully detached: shock acceleration exceeds what the locking feature can hold.
PCB bending fracture: large thin boards develop excessive bending stress under shock.
Solder joint cracking: fatigue cracks initiate under combined shock load and thermal stress.
Enclosure fracture or latch breakage: insufficient structural strength or stress concentration.
Sensor failure: accelerometers, gyroscopes and similar devices driven beyond their operating range.
Design recommendations
Increase the strength of connector locking features, adding mechanical locks or dual-point locking where necessary.
Add support posts and trace reinforcement on large PCBs to reduce deformation under vibration and shock.
Add retention for brittle components such as connectors, crystals and electrolytic capacitors.
Avoid stress concentration points in the structure, adding fillets where needed.
Consider mechanical damping structures for shock-sensitive devices such as MEMS sensors.
Frequently asked questions
Do shock and vibration both need to be tested?
Yes; one cannot replace the other. Vibration examines fatigue under sustained excitation; shock examines structural retention under transient high load. Both occur in real use, and some products pass shock but fail vibration (adequate connector locking strength but poor solder joint fatigue resistance).
Does shock testing need a large number of samples?
Shock can be destructive, and a failed sample cannot be used for other items. Prepare dedicated shock samples, or agree the sample allocation sequence during project planning — placing shock after vibration and temperature cycling.
Service notes
Our laboratory holds both CMA and CNAS accreditation, covers about 10,000 m2 and runs more than 500 sets of equipment. All testing is carried out in our own laboratories — nothing is subcontracted. Plant visits and on-site witnessed testing are welcome.
Scheduling follows the actual project pipeline. You can state your preferred lead time when you submit samples; we will confirm a feasible plan against current capacity and keep you updated at each milestone. Once the report is issued we send the electronic copy; corrective-action advice can be arranged separately.
