TVAC, Shock and Vibration Testing all on one Site
Vibration testing is a critical environmental verification activity for spacecraft, instruments, mechanisms, payloads and flight hardware. During launch, hardware is exposed to complex dynamic loads generated by propulsion systems, aerodynamic forces, structural coupling, engine and turbopump operation, and stage or fairing events. These environments can challenge structures, fasteners, electronic assemblies, connectors, optical equipment and sensitive mechanisms.
Within an ECSS-based verification programme, vibration testing can contribute objective evidence for qualification, acceptance or protoflight verification. The applicable test philosophy, levels, durations, axes, monitoring requirements and success criteria depend on the product, launcher environment, mission criticality, model philosophy and customer-approved tailoring.
Vibration testing is normally integrated with functional testing and may form part of a wider environmental campaign involving thermal vacuum, shock, acoustic and electromagnetic compatibility testing. It should not be treated as an isolated shaker activity. The test must remain connected to defined requirements, an approved hardware configuration, representative interfaces, suitable fixtures and agreed acceptance criteria.
Engineers care about vibration testing because dynamic failures can arise from inadequate load definition, insufficient design margin, workmanship defects, fixture interaction or configuration changes that have not been adequately reverified. A well-planned campaign helps identify these risks before launch and produces traceable evidence for verification closure, flight readiness and mission assurance decisions.
Vibration testing is the controlled application of dynamic mechanical excitation to a test article. It is used to assess structural integrity, functional performance, workmanship robustness and dynamic behaviour under defined launch, transportation or operational environments.
The test article is mounted to a controlled electrodynamic or hydraulic excitation system through a representative fixture. Input and response measurements are captured using calibrated instrumentation. Testing may be conducted in one or more orthogonal axes, depending on the hardware configuration and approved test specification.
The objective is not simply to reproduce motion. It is to generate technically relevant evidence against defined verification requirements.
A low-level sinusoidal sweep is normally performed to identify natural frequencies and structural response characteristics. When conducted before and after higher-level testing, it provides a baseline for comparing the hardware’s dynamic signature.
Why is resonance search performed before and after vibration testing?
It helps identify frequency shifts or response changes that may indicate loosening, structural change, damage or a change in the hardware-to-fixture interface. The acceptance criteria and allowable changes should be defined before testing.
Sinusoidal vibration testing applies controlled swept-sine excitation over a defined frequency range. It is commonly used to assess structural response to low-frequency launch loads and other discrete or narrow-band dynamic environments.
Testing may be performed on three orthogonal axes where required by the approved test specification.
What does sinusoidal vibration testing verify?
It can support verification of structural integrity, load-path capability and resistance to defined low-frequency dynamic loading. The actual evidence produced depends on the approved levels, duration, fixture, instrumentation and acceptance criteria.
Random vibration testing applies broadband excitation across a defined frequency range. The input is normally specified using a Power Spectral Density profile, often abbreviated to PSD.
Random vibration is widely used to represent broadband launch vibration. However, the correct profile must be derived from launcher, mission, customer or project requirements. A generic random profile should not be assumed to represent every launch environment.
Why is random vibration widely used for launch verification?
Launch vibration contains energy across a broad frequency range. Random vibration provides a controlled method of applying and measuring broadband excitation against a defined spectrum.
Sine burst testing applies high-amplitude, low-frequency sinusoidal loading over a limited number of cycles. It may be used to demonstrate structural capability against specified quasi-static or limit-load conditions when this approach is selected within the approved verification strategy.
When is sine burst testing used?
It may be used where structural load capability needs to be demonstrated and where static testing, centrifuge testing, spin testing or analysis is not the selected verification method.
Modal survey testing identifies natural frequencies, damping characteristics and mode shapes. The results can be correlated with finite element models to improve confidence in structural predictions.
Why perform a modal survey?
A modal survey helps verify whether the analytical model represents the physical structure with sufficient accuracy for the intended dynamic assessment.
Notching is the controlled reduction of input at selected frequencies to limit excessive test article response or interface loads. It is used to avoid unrealistic over-testing while preserving the defined verification objective.
Notching criteria should be based on approved load limits, analysis, force limits, response limits or other technically justified controls. The strategy should be agreed with the customer before test execution.
Does notching reduce test quality?
Not when it is technically justified, controlled and documented. Poorly defined notching can under-test hardware. Properly applied notching can prevent non-representative loading without compromising the intended verification evidence.
Functional monitoring records the operational behaviour of hardware during vibration exposure. Monitoring may include telemetry, electrical continuity, sensor outputs, communications, power consumption or other mission-relevant functions.
Is functional monitoring required during vibration testing?
The requirement depends on the hardware, operational configuration and approved test specification. Where intermittent or vibration-induced functional failures are credible, monitoring provides valuable evidence and improves anomaly detection.
The principal engineering objectives are to:
Demonstrate survival of defined launch or transportation loads.
Verify structural and functional design margins.
Identify structural weaknesses.
Detect workmanship defects.
Assess the stability of resonant behaviour.
Validate or correlate dynamic analysis and mathematical models.
Support qualification, acceptance or protoflight verification.
Generate objective evidence for verification closure.
Reduce residual technical and mission risk.
Dynamic environment definition.
Launcher load analysis.
Finite element modelling.
Preliminary modal analysis.
Structural margin assessment.
Interface and mounting definition.
Verification-method selection.
Workmanship control.
Configuration management.
Assembly inspections.
Fastener and interface verification.
Review of manufacturing changes.
Confirmation of test article representativeness.
Environmental verification campaigns.
Equipment-level testing.
Subsystem testing.
Space segment element testing.
Functional monitoring.
Anomaly recording and investigation.
Pre-test and post-test inspections.
Qualification verification.
Acceptance verification.
Protoflight verification.
Requirement traceability.
Verification Control Document closure.
Generation and review of objective evidence.
Demonstration of defined launch survivability.
Review of anomalies, deviations and waivers.
Residual-risk assessment.
Confirmation of configuration status.
Support for customer acceptance and readiness decisions.
Vibration testing can expose design weaknesses, loose interfaces, connector issues, structural resonances, fatigue concerns and workmanship defects before launch. Finding these issues during a controlled ground campaign is normally less costly and less damaging than discovering them after integration or during flight.
Testing does not eliminate risk. It provides evidence that defined risks have been assessed under agreed conditions.
The ECSS framework supports a structured approach to verification through analysis, test, inspection and review of design. Vibration testing is one possible verification method for applicable structural, functional and environmental requirements.
Applicability is project-specific. The test programme must reflect the approved verification strategy and tailoring rather than treating every possible vibration activity as automatically mandatory.
A controlled vibration campaign produces measurements, plots, configuration records, inspection results, functional data and review evidence. When these outputs are traceable to requirements and acceptance criteria, they support defensible verification decisions.
Successful vibration verification increases confidence that hardware can survive the defined launch environment and arrive in orbit without unacceptable structural or functional degradation. That confidence depends on representative hardware, appropriate profiles, controlled execution and technically sound interpretation of the results.
Depending on the product and project, applicable documents can include:
| ECSS document | Typical relevance |
|---|---|
| ECSS-E-ST-10 | System engineering framework and overall technical process |
| ECSS-E-ST-10-02 | Verification requirements, methods and evidence |
| ECSS-E-ST-10-03 | Testing requirements, planning, execution, reviews and reporting |
| ECSS-E-ST-32 | Structural engineering principles |
| ECSS-E-ST-32-10 | Structural factors of safety |
| ECSS-E-ST-32-11 | Modal survey assessment |
| ECSS-Q-ST-20 | Quality assurance requirements |
| ECSS-Q-ST-20-07 | Quality assurance requirements for test centres |
| ECSS-M-ST-40 | Configuration and information management |
Only documents genuinely applicable to the product and programme should be included in the controlled standards list. Document titles, issue status, revision and applicability must be confirmed against the project’s approved baseline before use.
An ECSS-aligned vibration programme can include requirements for:
Qualification testing.
Acceptance testing.
Protoflight testing.
Test documentation.
Test planning and sequencing.
Test readiness activities.
Test reviews.
Approved procedures.
Test input tolerances.
Measurement uncertainty.
Configuration control.
Anomaly and nonconformance management.
Test reporting.
Verification evidence and closure.
The detailed requirements depend on the product, customer, contract and approved tailoring.
ECSS requirements should be tailored in a controlled manner. Relevant considerations can include:
Mission criticality.
Launcher environment.
Product level.
Model philosophy.
Qualification status.
Previous flight heritage.
Similarity evidence.
Customer verification requirements.
Payload sensitivity.
Structural margins.
Test article availability.
Residual hardware life.
Schedule and cost constraints.
Consequences of over-testing or under-testing.
Tailoring does not mean ignoring requirements. It means selecting and adapting requirements through a justified, documented and approved process.
Agencies, launcher authorities, prime contractors and payload integrators may supplement ECSS with project-specific dynamic environments, test factors, force limits, notching criteria, instrumentation requirements and reporting formats.
Where different requirements interact, the programme should establish an approved hierarchy of documents. Conflicts should be resolved before the Test Readiness Review rather than during test execution.
Identify applicable requirements.
Define the verification objective.
Establish the model philosophy.
Determine whether the activity supports development, qualification, acceptance or protoflight verification.
Develop the Assembly, Integration and Test Plan.
Update the Verification Plan and Verification Control Document.
Generate the Test Specification.
Define success and failure criteria.
Agree customer, launcher and project-specific constraints.
Review hardware dimensions, mass and centre of gravity.
Confirm test article configuration.
Design and analyse the fixture.
Review fixture resonances and load paths.
Prepare the instrumentation plan.
Define control and response accelerometer positions.
Establish notching and abort criteria.
Prepare functional monitoring.
Confirm data acquisition requirements.
Complete facility and equipment readiness checks.
Conduct the Test Readiness Review.
Confirm approved configuration and documentation.
Perform the baseline functional test.
Complete visual and configuration inspections.
Conduct the pre-test resonance search where specified.
Perform sine, random, sine burst or other approved activities.
Test each required axis.
Apply approved notching and control limits.
Monitor hardware functions where required.
Record deviations and anomalies.
Conduct post-test resonance searches, inspections and functional checks.
Hold the Post-Test Review where required.
Review control and response data.
Compare pre-test and post-test signatures.
Assess frequency shifts and response changes.
Correlate results with analysis where applicable.
Evaluate anomalies and nonconformances.
Confirm whether acceptance criteria were satisfied.
Identify additional analysis or testing needs.
Issue the approved Test Report.
Close applicable Verification Control Document items.
Resolve NCRs, deviations, waivers and review actions.
Confirm final configuration status.
Conduct the Test Review Board where required.
Deliver the agreed evidence package.
Support customer verification and flight-readiness decisions.
Test only the approved configuration. Record hardware, software, firmware, fixtures, cables, interfaces and instrumentation that could affect the result.
Link each activity, profile and acceptance criterion to an approved requirement. The Test Report should show how the resulting evidence supports verification closure.
Use equipment, instrumentation and data-acquisition systems suitable for the required levels, frequency range, payload and uncertainty. Confirm calibration status and applicable quality controls.
Start fixture design before the hardware is ready for test. Late fixture work is a common cause of schedule delay and technical compromise.
Use agreed response, force or load limits supported by analysis or approved criteria. Record when and why notching occurred and how it affected the achieved input.
Use experienced engineering, test and quality personnel to review requirements, fixtures, instrumentation, procedures, risks and acceptance criteria.
Where operationally relevant, monitor the hardware during vibration rather than relying solely on pre-test and post-test checks.
Define abort limits before testing. Operators should not be required to invent decisions during an unexpected response or anomaly.
Resolve or formally disposition NCRs, waivers, deviations and review actions before advancing to the next axis, environmental test or programme phase.
The campaign demonstrates the applicable vibration verification requirements under the approved conditions and acceptance criteria.
Relevant Verification Control Document items are closed using objective, reviewed and traceable evidence.
The hardware shows no unacceptable structural, functional or workmanship degradation.
Pre-test and post-test comparisons remain within approved criteria, or any changes are investigated and accepted through the programme’s control process.
There is a complete link between requirements, configuration, procedures, measurements, results, anomalies and verification decisions.
The customer accepts the resulting evidence package as sufficient for the applicable readiness decision. The test laboratory provides evidence. Final acceptance, qualification and flight-release authority remain with the responsible customer or programme authority.
Establish the applicable launch, transportation and mission vibration environments. Inputs may come from launcher documentation, coupled-load analysis, mission requirements, customer specifications or measured data.
Develop dynamic predictions, identify critical responses and establish structural margins. Analysis should inform the test strategy, instrumentation and notching approach.
Create a fixture that represents the flight interface and transfers the required loads without introducing unacceptable fixture behaviour. Fixture stiffness, mass, natural frequencies, fasteners and mounting arrangements require review.
Identify natural frequencies and track changes in dynamic behaviour. Results should be assessed against predefined criteria rather than interpreted informally after testing.
Apply the approved broadband PSD profile with defined tolerances, duration, axes and control strategy.
Apply the approved swept-sine profile and monitor control and response channels for resonances, load exceedances or abnormal behaviour.
Capture mission-relevant performance during exposure where required. Monitoring should be planned, time-synchronised and included within the acceptance criteria.
Inspect the hardware, mounting interfaces, fasteners, connectors and visible structures. Confirm configuration status and complete the required functional checks before declaring the activity complete.
Incorrect or incomplete launcher environment definition.
Poor dynamic modelling.
Unrepresentative boundary conditions.
Fixture resonances or interaction effects.
Insufficient fixture stiffness.
Inadequate instrumentation.
Incorrect control-channel selection.
Poorly justified notching.
Over-testing or under-testing.
Undetected intermittent functional failures.
Late fixture design.
Hardware or documentation not ready for test.
Test facility availability.
Failed readiness reviews.
NCR investigation.
Additional analysis.
Requirement changes.
Repeat testing.
Delayed customer approvals.
Hardware damage.
Fixture redesign.
Additional instrumentation.
Campaign repetition.
Extended facility time.
Specialist analysis.
Programme delay.
Replacement of unavailable flight hardware.
Insufficient objective evidence.
Incomplete requirement traceability.
Incorrect test tailoring.
Ambiguous acceptance criteria.
Unapproved configuration changes.
Inadequate comparison of pre-test and post-test results.
Failure to close verification actions.
Poor configuration control.
Missing approvals.
Out-of-date standards.
Incomplete procedure records.
Weak anomaly documentation.
Missing calibration evidence.
Inconsistent test and verification reports.
A controlled vibration verification campaign may require:
Assembly, Integration and Test Plan.
Verification Plan.
Verification Control Document.
Dynamic Environment Specification.
Interface Control Document.
Coupled-load or structural analysis.
Fixture design and analysis records.
Test Specification.
Test Procedure.
Instrumentation Plan.
Functional Test Procedure.
Test Readiness Review package.
Post-Test Review package.
Test Report.
Verification Report.
Calibration records.
Configuration records.
Nonconformance reports.
Requests for deviation.
Requests for waiver.
Review actions and closure evidence.
Resonate Testing helps customers translate mission, launcher and project requirements into a practical vibration verification strategy. This can include review of model philosophy, test objectives, sequencing, profiles, axes, evidence needs and programme constraints.
Independent engineering support can be provided for:
Requirement interpretation.
Test tailoring.
Fixture concepts.
Instrumentation.
Control strategy.
Notching criteria.
Functional monitoring.
Acceptance criteria.
Risk identification.
Test readiness.
Support is available for development, qualification, acceptance and protoflight campaigns, subject to technical review, equipment suitability, scheduling and confirmation of the applicable accredited scope.
Resonate Testing can support the preparation or review of:
Assembly, Integration and Test Plans.
Test Specifications.
Test Procedures.
Instrumentation Plans.
Test Reports.
Verification documentation.
Review packages.
Evidence-delivery structures.
Resonate Testing can contribute technical input to:
Test Readiness Reviews.
Post-Test Reviews.
Test Review Boards.
Customer technical reviews.
Fixture and instrumentation reviews.
Anomaly and nonconformance discussions.
Support can begin during early programme planning and continue through test definition, readiness, execution, reporting and evidence delivery.
From its Northern Ireland facility, Resonate Testing supports customers across Ireland, the United Kingdom, Europe and international markets with practical environmental test engineering and space-sector verification support.
Every project remains subject to technical review. Applicable standards, hardware configuration, equipment suitability, fixture requirements, safety, schedule, accreditation status and reporting expectations should be confirmed before commitment.
Qualification testing is generally used to demonstrate design robustness and margin. Acceptance testing is generally applied to flight hardware to identify workmanship defects and confirm integrity at approved acceptance levels. The exact distinction depends on the project’s model philosophy and tailoring.
Protoflight testing applies an agreed verification approach to hardware intended for flight when a separate qualification model is not available. It requires careful control because the tested article must retain sufficient condition and life for flight.
Not automatically in every case. Applicability depends on the hardware, requirements, verification strategy, model philosophy, mission environment and approved tailoring. Vibration testing is, however, a common verification method for hardware exposed to launch and transportation loads.
A resonance search is a low-level sinusoidal sweep used to identify natural frequencies and response behaviour. Comparison before and after higher-level testing can help detect structural change.
Notching is a controlled reduction of input at selected frequencies to prevent excessive or non-representative response. It must be technically justified, approved and documented.
Not necessarily. Properly controlled notching can preserve representative interface loads while preventing unrealistic over-testing. The achieved environment and verification impact must be reviewed against the approved requirements.
Yes. Tailoring may address mission criticality, launcher environment, model philosophy, heritage, product sensitivity and customer requirements. Tailoring should be justified, documented and approved.
Typical evidence includes approved specifications and procedures, configuration records, calibration information, control and response data, functional results, inspections, anomaly records, review minutes, the Test Report and verification close-out documentation.
Where operationally relevant or required by the approved specification, functional monitoring is strongly recommended. It can detect intermittent failures that may not appear during post-test checks.
The test should be paused or aborted in accordance with the approved criteria. The anomaly is recorded, the configuration is preserved where practical, and the issue is assessed through the applicable nonconformance and review process before progression.
Three orthogonal axes are common, but the actual requirement depends on hardware orientation, symmetry, mission environment, mounting interface and approved test specification.
Useful inputs include:
Applicable standard or customer specification.
PSD, sine, sine burst or other profile.
Test levels and duration.
Required axes.
Hardware mass, dimensions and centre of gravity.
Drawings and mounting-interface details.
Fixture availability.
Instrumentation requirements.
Functional monitoring needs.
Notching and abort criteria.
Acceptance criteria.
Required reporting format.
Target test date.
Whether you’re looking to contact us for the first time or have another testing requirement, we’d love to hear from you.
