The equipment final peak sawtooth shock test is a standardized laboratory method used to verify the ability of products, components, and packaged goods to withstand non-repetitive mechanical shocks encountered during handling, transportation, and in-service operation. This test applies a terminal peak sawtooth acceleration pulse—defined in IEC 60068-2-27, GB/T 2423.5, and related standards—that delivers a nearly uniform shock response spectrum across a broad frequency range. This article explains the test principles, applicable sample types, test severities, laboratory methods, and typical industrial applications of this important shock qualification technique.
Technical Overview
The equipment final peak sawtooth shock test, also known as the terminal peak sawtooth pulse shock test, is a mechanical shock test in which a specimen is subjected to a single, controlled acceleration pulse. The pulse shape is defined by an acceleration that rises linearly from zero to a specified peak value and then returns to zero almost instantaneously, producing a characteristic asymmetric sawtooth waveform when plotted against time. This pulse shape is one of the three standard shock waveforms—alongside the half-sine pulse and the trapezoidal pulse—recognized by international environmental testing standards.
Pulse Shape Characteristics
Compared with the half-sine pulse of the same peak acceleration and duration, the ideal final peak sawtooth pulse generates a theoretical velocity change equal to half of the product of peak acceleration and pulse duration. More importantly, its shock response spectrum is significantly flatter, which means the energy delivered to the specimen is distributed far more uniformly across the frequency range. This makes the sawtooth pulse well suited to reproducing the composite shock environments caused by abrupt deceleration, collision, pyrotechnic separation events, and rough handling, where multiple structural resonance frequencies must be excited simultaneously and with comparable severity.
Governing Standards
- IEC 60068-2-27 / EN 60068-2-27: Environmental testing, Test Ea and guidance: Shock
- GB/T 2423.5: Environmental testing for electric and electronic products, Test Ea: Shock
- MIL-STD-810 (Method 516) and GJB 150.18A: Shock test methods for defense equipment
- ISO 2247 and ASTM D4169 related procedures for packaging and distribution simulation
- UL, JIS, and EIA test procedures referencing terminal peak sawtooth shock requirements
These standards specify the pulse shape, tolerance bands, test severities, mounting requirements, and measurement chain characteristics that accredited third-party laboratories must satisfy for results to be recognized in type testing and product certification programs.
Testing Samples
Electronic and Electrical Equipment
Typical specimens include computers, servers, telecommunication devices, power supplies, control cabinets, instrumentation, and household appliances. The test verifies that solder joints, connectors, relays, mounting hardware, and mechanical supports survive sudden impacts without degradation of electrical performance.
Military and Aerospace Hardware
Defense electronics, weapon system components, avionics, radar modules, and satellite equipment are frequently qualified using final peak sawtooth shock pulses to demonstrate survivability under gunfire vibration, ballistic impact, stage separation, landing shock, and battlefield transportation conditions described in military specifications.
Automotive, Rail, and Marine Components
Electronic control units, sensors, battery modules, lighting assemblies, and onboard equipment for vehicles, rolling stock, and ships are tested to confirm resistance to curb strikes, coupling shocks, hard landings, and cargo handling impacts encountered throughout the product life cycle.
Packaged Products and Small Components
Finished goods in their transport packaging, as well as discrete components such as semiconductors, relays, switches, and ceramic parts, may be subjected to high-peak, short-duration sawtooth pulses to evaluate package cushioning performance and component structural strength.
Testing Items
A complete final peak sawtooth shock test program addresses the following parameters, which are agreed between the manufacturer and the testing laboratory based on the applicable standard and the intended service environment:
- Peak acceleration, commonly ranging from 15 g (150 m/s²) for complete equipment up to several thousand g for small components
- Nominal pulse duration, typically from 0.1 ms to 18 ms depending on specimen mass and test severity
- Velocity change across the pulse, with typical allowable deviation of ±10% of the specified value
- Number of shocks, most commonly three consecutive shocks in each direction along three mutually perpendicular axes, for a total of 18 shocks
- Specimen orientation and mounting configuration, replicating actual in-service installation
- Specimen operating condition during test, including unpowered, powered, or functionally monitored states
- Acceptance criteria such as absence of visible damage, maintained structural integrity, and verified electrical or functional performance after testing
Representative severity combinations include 150 m/s²/11 ms, 300 m/s²/18 ms, 500 m/s²/11 ms, 1000 m/s²/6 ms, and 5000 m/s²/1 ms, with higher levels applied to ruggedized or miniature components as required by the product specification.
Testing Methods
Test Equipment
The test is performed using dedicated shock test machines, including free-fall shock towers, pneumatic impact testers, hydraulically actuated shock machines, and electrodynamic shakers equipped with waveform synthesis capability. The sawtooth waveform is typically generated by waveform programmers, such as deformable lead cones, elastomeric programmers, or programmable gas cushions, which shape the deceleration profile of the shock table to meet the specified pulse requirements.
Instrumentation and Measurement
A calibrated control accelerometer is rigidly mounted on the fixture as close as possible to the specimen attachment point. The measurement chain, including signal conditioning and data acquisition, must provide a frequency response that is flat within the limits specified by the governing standard, so that the measured pulse, its tolerance limits, and the residual velocity characteristics are faithfully captured. All instrumentation is traceable to national or international metrology standards.
Test Procedure
- Initial inspection: The specimen is examined visually and, where applicable, subjected to baseline functional and performance tests to establish reference conditions.
- Conditioning: The specimen is stabilized at specified ambient temperature and humidity conditions when required by the test plan.
- Mounting: The specimen is secured directly to the shock table or to a rigid fixture using bolts or clamps that reproduce the intended service mounting, with mounting resonance minimized.
- Pulse verification: Calibration runs are conducted to confirm that the achieved waveform falls within the tolerance bands for peak acceleration, pulse duration, and velocity change before the specimen is exposed.
- Shock application: The specified number of shocks is applied sequentially in each of the six orthogonal directions, with pulse quality verified and recorded for every impact.
- Final inspection and evaluation: The specimen is re-examined and functionally tested against the acceptance criteria defined in the product specification or test standard.
Pulse Tolerances and Verification
The measured pulse must remain within the reference tolerance bands published in IEC 60068-2-27 and GB/T 2423.5. Typical requirements limit peak acceleration deviation to approximately ±15%, restrict pulse duration deviation, constrain the velocity change to ±10%, and limit cross-axis and residual acceleration to a fraction of the nominal peak. Accredited third-party laboratories document waveform traces for every shock to demonstrate full compliance.
Applications
Final peak sawtooth shock testing is widely applied across industries where products must survive high-intensity, low-repetition mechanical impacts:
- Defense and military qualification of tactical electronics, munitions hardware, and communication systems under military shock specifications
- Aerospace verification of avionics, launch vehicle components, and spacecraft subsystems against separation and landing shocks
- Automotive and electric vehicle validation of electronic control units, battery systems, and onboard devices against road and handling impacts
- Consumer electronics reliability testing for laptops, displays, portable instruments, and packaged retail products
- Industrial equipment qualification for machinery controllers, drive units, and instrumentation installed in shock-prone environments
- Packaging design verification and transport hazard simulation for fragile goods and high-value cargo
- Regulatory compliance, type approval, and supplier qualification programs requiring evidence from accredited third-party laboratories
FAQ
What is the difference between a final peak sawtooth pulse and a half-sine pulse?
A half-sine pulse rises and falls symmetrically, while a final peak sawtooth pulse rises linearly to its maximum and terminates abruptly. The sawtooth pulse produces a flatter shock response spectrum, delivering more uniform energy across frequencies, which better reproduces complex real-world impact environments such as collisions and pyrotechnic events.
How many shocks are applied in a typical test?
Most specifications require three shocks in each of the six orthogonal directions along three perpendicular axes, for a total of eighteen shocks. Product-specific or military specifications may define different quantities based on the expected service exposure.
Which standards govern the final peak sawtooth shock test?
The primary references are IEC 60068-2-27 and GB/T 2423.5 for electrical and electronic products, together with MIL-STD-810 Method 516 and GJB 150.18A for defense applications. Additional requirements appear in UL, JIS, and ISO/ASTM-based procedures for specific product categories.
What parameters define the test severity?
Test severity is defined by the combination of peak acceleration, pulse duration, and the resulting velocity change, together with the number of shocks and the axes tested. These values are selected to envelope the shocks expected during production handling, transport, installation, and operation.
Can the test be performed on operating equipment?
Yes. Many test plans require the specimen to be powered and functionally monitored during shock exposure to detect transient faults, contact bounce, or momentary performance interruptions that would not be revealed in an unpowered test.
How are test results reported?
An accredited third-party laboratory issues a test report documenting the applied severities, verified waveform traces, mounting configuration, specimen condition, any observed anomalies, and the pass/fail conclusion against the specified acceptance criteria.