FEA · CFD · NVH · THERMAL · ACOUSTIC — ENGINEERING SIMULATION
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SPEC SHEET S-03 · REV A · UPDATED SEP 2026

S-03 · NVH & DYNAMICS

Will it resonate? Frequencies, responses and fatigue life under real vibration.

Modal, harmonic, random and shock analysis of structures, machines and electronics — the natural frequencies kept clear of the excitation, the dynamic stresses computed, and the fatigue life of the critical details checked against your test profile or standard.

([K] − ω²[M]){φ} = 0f_n vs. f_excmargin · σ_rms · D ≤ 1
Submit a Problem Statement Sample report outline ↓
[✓] NDA before data exchange[✓] Fixed scope & price[✓] Independent internal check
FIG. 1 — Ground excitation · dynamic response SCHEMATIC outer frameinner frame
S-03 · AT A GLANCESPEC
TYPICAL SCOPE
Machine frames and skids, mounted equipment, electronics enclosures, vehicle and rail components
DELIVERABLE
Signed PDF report, frequency and response tables, damage per detail
LEAD TIME
Agreed in the written scope
ANALYSES
Modal · harmonic · random (PSD) · shock · response spectrum
CONFIDENTIALITY
NDA signed before any file is exchanged
QUALITY
Mode-set completeness and hand check in every report
Get a scoped quote →

01 / WHEN YOU NEED IT

Questions this analysis answers.

Vibration problems are expensive because they show up late: a cracked bracket after a road test, a failed qualification, or a machine that shakes at one speed only.

We start from the excitation — speed, road, test profile or earthquake — and follow it through the structure to the detail that decides the design.

Q1Are the natural frequencies clear of the running speeds?→ Modal analysis + Campbell diagram
Q2Why does it shake at one speed only?→ Harmonic response, root cause
Q3Will it survive the vibration qualification test?→ Random vibration + spectral fatigue
Q4Will it survive the shock or drop load?→ Shock / transient dynamics
Q5Will the equipment stay functional in an earthquake?→ Response-spectrum analysis
Q6Do the isolators actually isolate?→ Isolation design & transmissibility

02 / DELIVERABLES

What you receive. In writing, before we start.

Each item is listed in the scope document you sign off. Nothing on this list is a surprise at the end.

PDF

Technical report

Scope, excitation, assumptions, model, results and conclusions. Signed and revision-controlled.

XLSX · PDF

Frequency & response tables

Natural frequencies, effective mass, separation margins and peak responses per case.

IN REPORT

Mode shapes & response plots

Mode shapes, FRFs and stress plots that show where and why the structure moves.

IF ROTATING

Campbell diagram

Frequencies against speed with excitation orders — where resonance can occur.

APPENDIX

Verification appendix

Mode-set completeness, mesh sensitivity, hand check of the first mode, damping sensitivity.

IN REPORT

Design recommendations

Stiffening, mass or isolator changes that move a frequency or reduce a response.

3 H ONLINE

Results review meeting

A walk-through with your engineers. Questions answered and recorded in the final revision.

Revision round

Re-run for design changes within the agreed scope, with a revision log in the report.

03 / METHODS

The right analysis for the question — not the most expensive one.

Every dynamic study starts with a modal analysis; the excitation then decides whether the response is computed in frequency, in time, or statistically.

FIG. 0 — Mode shapes 1–3 (schematic)
ANALYSISUSE IT WHENKEY OUTPUTTYPICAL REFERENCE
Modal analysisAlways first — to know the frequencies and shapes the excitation can driveNatural frequencies, mode shapes, effective modal massMode set ≥ 90 % mass
Harmonic responseRotating machinery, periodic forces, sine-sweep testsFRFs, peak amplitudes and stresses vs. frequencyIEC 60068-2-6 · ISO 20816
Random vibration (PSD)Transport, road and qualification test profiles1σ / 3σ responses, spectral fatigue damageIEC 60068-2-64 · MIL-STD-810H 514.8
Shock & transientDrops, impacts, pyro and handling shocks, start-up transientsPeak acceleration, stress and displacement historiesIEC 60068-2-27 · MIL-STD-810H 516.8
Response spectrumSeismic qualification of structures and equipmentCombined modal response (SRSS / CQC)EN 1998-1 · ASCE 7
Rotating machinerySpeed-dependent excitation; critical speedsCampbell diagram, separation margins
Test–simulation correlationMeasured frequencies or FRFs are availableFrequency error, MAC matrix, updated model→ with your test data
FIG. 2 — Resonance and damping — single-DOF responseSCHEMATIC
Δf ≈ 2ζ·f_n ζ = 0.05 · Q = 10 ζ = 0.10 · Q = 5 ζ = 0.20 |H| = 1 (static) f = f_n 0 2·f_n frequency ratio f / f_n → amplification |H| At f = f_n the response is limited only by damping: Q ≈ 1/(2ζ). A few percent of damping decides the peak, so the damping value and its source are always stated in the report.
FIG. 3 — Campbell diagram — modes vs. excitation ordersSCHEMATIC
mode 1 · 38 Hz mode 2 · 71 Hz mode 3 · 104 Hz 1× 2× 3× operating range 0 1500 3000 speed [rpm] → frequency [Hz] Each crossing of a mode with an excitation order is a possible resonance. Here the 3× line meets mode 2 inside the operating range — the case a design change must remove. (Illustrative values.)

04 / PROCESS & TIMELINE

From problem statement to signed report.

Five steps, each with a clear hand-off. You always know what we need from you and what you get back.

  1. 012 day

    Scoping call

    FROM YOUProblem statement, drawings, test or field data
    FROM USNDA, list of questions and missing data
  2. 022 days

    Scope & fixed quote

    FROM YOUExcitation, masses, acceptance criteria
    FROM USWritten scope, assumptions, damping basis, price
  3. 037 days

    Modal model

    FROM YOUCAD, masses, connection and isolator data
    FROM USInterim check-in: frequencies and mode shapes
  4. 042 days

    Response & verify

    FROM YOUNothing — internal step
    FROM USResponses, fatigue, verification evidence, second-engineer review
  5. 052 days

    Report & review

    FROM YOUYour comments on the draft
    FROM USSigned report, files, review meeting

05 / INPUTS

What we need from you.

REQUIRED
  • [✓]Geometry — STEP / IGES / Parasolid, or dimensioned drawings
  • [✓]Masses of mounted equipment and how they are attached
  • [✓]The excitation — speeds and orders, force spectra, test profile (PSD / sine / shock) or response spectrum
  • [✓]How and where the structure is supported or isolated
  • [✓]Acceptance criteria — frequency separation, amplitude or velocity limits, fatigue life
  • [✓]The decision the result feeds, and the deadline
HELPFUL IF AVAILABLE
  • [+]Measured vibration data or failed-test records
  • [+]Damping values from tests or supplier data
  • [+]Isolator and bushing stiffness data
  • [+]Photos of cracks or wear
  • [+]Comments from your customer or approver
INCOMPLETE DATA?Most projects start that way.We list what's missing in the scoping call. Anything we have to assume is recorded in the report's assumption register — never hidden in the model.

06 / THE REPORT

See the report before you buy it.

A signed, revision-controlled report of 60 pages on average. Every frequency, response and damage value is traced to a load profile, a damping assumption and a mode set shown to be complete.

  1. T1
    Assumption registerEvery assumption — above all damping and connection stiffness — numbered and justified.
  2. T2
    Excitation traceabilityEach response names its load profile, axis and the clause or test it comes from.
  3. T3
    Verification evidenceMode-set completeness, hand check of the first mode and mesh sensitivity — included.
  4. T4
    Reproducible modelSolver, version, element types, damping model and frequency range are stated.
  5. T5
    Plain-language conclusionOne page a manager can read: passes the test or not, the margin, and what to change.

07 / APPLICATIONS

Typical structures and equipment.

Machine frames & skidsRunning speeds · unbalance · resonance
Gensets & rotating equipmentEngine orders · isolators · foundations
Electronics & enclosuresQualification PSD · shock · transport
Vehicle componentsRoad loads · brackets · durability
Rail equipmentUnder-frame equipment · IEC 61373
Structures & platformsSeismic · footfall · machine-induced
Marine equipmentEngine and propeller excitation · shock
Aerospace & defenseMIL-STD test profiles · random · shock

08 / STANDARDS

Checked to the clause your approver reads.

Test profiles, severity limits and acceptance criteria are taken from the standard your product is qualified to — cited in the report.

STANDARDWHAT WE USE IT FOR
IEC 60068-2-6Sinusoidal vibration testing
IEC 60068-2-64Broadband random vibration testing
IEC 60068-2-27Shock testing
MIL-STD-810HEnvironmental test methods — Method 514.8 vibration, 516.8 shock
ISO 20816-1Measurement and evaluation of machine vibration
EN 1998-1Seismic design — response-spectrum analysis
ISO 8528-9Generating sets — measurement and evaluation of mechanical vibration

09 / HOW TO ENGAGE

Three ways to work with us.

Prices are fixed per written scope. You pay for the answer to a defined question, not for open-ended hours.

E-01PROJECT

Fixed-scope project

BEST FOR
A defined part or structure with a clear question
PRICE
Fixed quote after scoping
Start with a problem statement
E-02RETAINER

Engineering retainer

BEST FOR
Design teams with recurring analysis needs
PRICE
Quoted per scope
Discuss a retainer
E-03REVIEW

Third-party review

BEST FOR
Checking an FEA or hand calculation done by someone else
PRICE
Fixed quote
Request a review

10 / FAQ

Asked before every project.

Something else? Ask it in the problem statement — the answer comes with the scope.

Which software do you use?

Tessera — the solver we build — runs the free calculators on this site today, each published with its reference cases. For project work the solver is chosen against the standard the result must satisfy, and named in the written scope. Every report states the solver, version, element types, damping model and frequency range.

Where does the damping value come from?

From your test data if available; otherwise from recognised references for the construction type. The value, its source and a sensitivity check are in the report.

Can analysis replace the vibration test?

Usually not for qualification — but it tells you before the test whether the design will pass, and why it failed if it did.

Can you use our measured data?

Yes. Measured frequencies or FRFs are used to correlate and update the model, and the correlation is reported.

Our part failed a test. Can you find out why?

Yes — we rebuild the test in the model, find the mode and detail that failed, and check the fix before the re-test.

How is the price set?

Per written scope: model size, number of load profiles and axes, and whether fatigue or transient analysis is needed.

RELATED CAPABILITIESAll services →
S-01 · STRUCTURAL Structural / FEA σ_vM ≤ f_y / γ_M0 Spec sheet →
S-02 · FLUID CFD ∇·(ρuu) = −∇p + ∇·τ Spec sheet →
S-04 · THERMAL Thermal ρc_p ∂T/∂t = ∇·(k∇T) + q Spec sheet →
S-05 · ACOUSTIC Acoustics ∇²p − (1/c²) ∂²p/∂t² = 0 Spec sheet →
S-06 · CONCEPT Concept & Design min f(x) s.t. g(x) ≤ 0 Spec sheet →

11 / PROBLEM STATEMENT

Send the excitation. Get a written scope back.

Tell us what vibrates, what excites it and which test or limit it must pass. We reply with questions or a fixed scope.

  • [✓] NDA before data exchange
  • [✓] Response within 2 business day(s)
  • [✓] Scope, assumptions & acceptance criteria in writing