Vibration damping performance testing service

Vibration Damping Performance Testing Service – Accredited ISO/IEC 17025 Mechanical Energy Dissipation Assessment for the Croatian Market

Vibration damping performance is a critical mechanical property that quantifies the ability of materials, components, and systems to dissipate vibrational energy, reduce resonance amplitudes, and attenuate the transmission of mechanical vibrations. This property is essential for ensuring the comfort, durability, reliability, and safety of products used in automotive, aerospace, industrial machinery, construction, consumer electronics, and medical device applications, where excessive vibration can lead to fatigue failure, noise generation, reduced performance, and premature wear. In the Croatian market, where the Hrvatski zavod za norme (HZN), the Ministarstvo gospodarstva i održivog razvoja, the Državni inspektorat, and the Carinska uprava enforce strict quality, safety, and performance standards aligned with EU directives and HRN EN (Croatian standards based on European norms), the accurate evaluation of vibration damping performance is essential for product certification, supplier qualification, type testing, quality control in manufacturing, and import-export processes. Our laboratory offers a comprehensive vibration damping performance testing service, applying standardized methods such as ASTM E756, ISO 6721, SAE J1637, and HRN EN ISO 6721 to measure damping loss factor, dynamic stiffness, transmissibility, and resonance characteristics under controlled frequency, temperature, and amplitude conditions. All tests are performed under our ISO/IEC 17025 (CNAS) accreditation, and the resulting reports are fully accepted by Croatian authorities and notified bodies, making them indispensable for regulatory compliance, product validation, and market access in Croatia and the European Union.

Vibration Damping Samples and Materials We Regularly Test

Our laboratory receives a wide variety of materials, components, and systems for vibration damping performance testing. Typical samples include:

• Viscoelastic damping materials – rubber compounds, elastomers, polyurethanes, silicones, and constrained-layer damping materials.
• Structural damping treatments – damping tapes, sheets, coatings, and spray-applied damping compounds for automotive and industrial applications.
• Anti-vibration mounts and isolators – rubber mounts, spring isolators, air springs, and elastomeric bushings for machinery and vehicle suspensions.
• Composite and laminated materials – fiber-reinforced composites with integrated damping layers for aerospace and automotive structures.
• Automotive and transportation components – engine mounts, suspension bushings, exhaust hangers, and interior trim panels with damping treatments.
• Industrial machinery and equipment parts – pump bases, compressor mounts, fan isolators, and machine tool vibration dampers.
• Prototype and new damping material formulations – submitted by manufacturers for validation of damping performance before series production.
• Field-retrieved components – for failure analysis and remaining damping life assessment.

Damping Loss Factor Measurement – Evaluating Energy Dissipation Capacity

The damping loss factor (η) is the primary parameter for quantifying the energy dissipation capacity of a material or component. Our tests measure the loss factor using a variety of methods, including the Oberst beam method, the dynamic mechanical analysis (DMA) method, and the half-power bandwidth method. These methods follow international standards and the requirements of the Croatian automotive, aerospace, and industrial sectors.

• Oberst beam method for damping loss factor (ASTM E756 / ISO 6721-3 / HRN EN ISO 6721-3 / NTC 5600 – for viscoelastic materials) – we prepare a cantilever beam specimen consisting of a metal substrate with the damping material applied to one side. The beam is excited at its resonant frequency, and the frequency response function (FRF) is measured using an accelerometer and a signal analyzer. The damping loss factor (η) is calculated from the half-power bandwidth of the resonance peak, using the formula: η = (f2 – f1) / fr, where f1 and f2 are the frequencies at the half-power points and fr is the resonance frequency. The test is performed at a specified temperature (e.g., 23 °C, 40 °C, 60 °C) and at multiple frequencies (e.g., 10 Hz, 50 Hz, 100 Hz, 500 Hz). We report the damping loss factor, the resonance frequency, and the half-power bandwidth.
• Dynamic mechanical analysis (DMA) – ASTM D4065 / ISO 6721-1 / NTC 5601 – for the direct measurement of the loss factor) – we use a dynamic mechanical analyzer (DMA) to apply a sinusoidal strain (or stress) to the specimen at a specified frequency and temperature. The storage modulus (E'), the loss modulus (E''), and the damping loss factor (tan δ = E'' / E') are measured directly. We report the loss factor (tan δ), the storage modulus, the loss modulus, and the glass transition temperature (Tg).
• Half-power bandwidth method (NTC 5602 – for the component-level damping measurement) – we excite the component (e.g., a mount, a panel, or a structure) at its resonant frequency using a shaker or an impact hammer. The frequency response function is measured, and the damping loss factor is calculated from the half-power bandwidth of the resonance peak. We report the loss factor, the resonance frequency, and the damping ratio.
• Damping loss factor at different temperatures (NTC 5603 – for the temperature dependence) – we perform the damping loss factor measurement at multiple temperatures (e.g., -20 °C, 0 °C, 23 °C, 40 °C, 60 °C, 80 °C) to evaluate the temperature dependence of the damping performance, which is critical for applications in diverse Croatian climates. We report the loss factor at each temperature and the temperature-damping curve.
• Damping loss factor at different strain amplitudes (NTC 5604 – for the amplitude dependence) – we perform the damping loss factor measurement at different strain amplitudes (e.g., 0.01 %, 0.1 %, 1 %) to evaluate the amplitude dependence of the damping (which is important for elastomers and non-linear materials). We report the loss factor at each strain amplitude.

Dynamic Stiffness and Transmissibility Measurement – Evaluating the Isolation Performance

Dynamic stiffness and transmissibility are key parameters for evaluating the vibration isolation performance of mounts, isolators, and suspension systems. Our tests measure the force transmitted through the component as a function of the frequency and the applied displacement, providing data for the design of effective isolation systems.

• Dynamic stiffness measurement (ISO 10846 / SAE J1637 / NTC 5610 – for elastomeric mounts and isolators) – we mount the test component (e.g., a rubber bushing or an isolator) between a shaker and a load cell. A sinusoidal displacement is applied at a specified frequency and amplitude, and the dynamic force transmitted is measured. The dynamic stiffness (Kd) is calculated as the ratio of the force amplitude to the displacement amplitude. The test is performed at multiple frequencies (e.g., 1 Hz to 100 Hz) and at a specified temperature. We report the dynamic stiffness (in N/mm) as a function of the frequency, and the phase angle between the force and the displacement.
• Transmissibility measurement (ISO 10846 / NTC 5611 – for the isolation performance) – we measure the transmissibility (the ratio of the output acceleration to the input acceleration) of the mount or the isolator over a frequency range (e.g., 1 Hz to 200 Hz). The transmissibility curve reveals the resonance frequency and the isolation region. We report the transmissibility curve, the resonance frequency, and the isolation efficiency (in %).
• Static and dynamic stiffness ratio (NTC 5612 – for the non-linear stiffness evaluation) – we measure the static stiffness (K_s) and the dynamic stiffness (K_d) of the mount, and we calculate the dynamic-to-static stiffness ratio (K_d / K_s). A high ratio indicates a high sensitivity to dynamic loads. We report the static stiffness, the dynamic stiffness, and the ratio.
• Effect of preload on dynamic stiffness (NTC 5613 – for the preload sensitivity) – we measure the dynamic stiffness at different preload levels (e.g., 10 %, 50 %, 100 % of the rated load) to evaluate the effect of the preload on the isolation performance. We report the dynamic stiffness at each preload level.
• Effect of temperature on dynamic stiffness (NTC 5614 – for the temperature sensitivity) – we measure the dynamic stiffness at different temperatures (e.g., -20 °C, 23 °C, 60 °C) to evaluate the effect of temperature on the isolation performance. We report the dynamic stiffness at each temperature.

Resonance Frequency and Modal Analysis – Identifying Critical Frequencies

The resonance frequency of a component or structure is the frequency at which the vibration amplitude is maximized, and it is a critical parameter for avoiding fatigue failure and excessive noise. Our tests identify the resonance frequencies and the corresponding mode shapes, providing essential data for the design of vibration-resistant structures.

• Resonance frequency measurement (ASTM E1876 / ISO 12680-1 / NTC 5620 – for the natural frequency detection) – we use an impact hammer (or a shaker) to excite the test specimen, and we measure the response using an accelerometer. The frequency response function (FRF) is calculated, and the resonance frequencies (the peaks in the FRF) are identified. We report the resonance frequencies (in Hz) and the damping ratios for each mode.
• Modal analysis (NTC 5621 – for the mode shape identification) – we perform a modal analysis by measuring the FRF at multiple points on the test specimen. The mode shapes (the deflection patterns) are identified for each resonance frequency. We report the mode shapes and the resonance frequencies.
• Effect of damping on the resonance amplitude (NTC 5622 – for the resonance control) – we measure the amplitude of the resonance peak with and without the damping treatment, and we calculate the reduction in the amplitude (in %). The reduction is a measure of the damping effectiveness. We report the amplitude reduction and the damping efficiency.
• Resonance frequency shift due to temperature (NTC 5623 – for the thermal effect) – we measure the resonance frequency at different temperatures to evaluate the effect of temperature on the natural frequency (due to changes in the material's modulus). We report the resonance frequency at each temperature.
• Resonance frequency shift due to aging (NTC 5624 – for the aging effect) – we measure the resonance frequency before and after the aging of the material (e.g., thermal aging, UV exposure), to evaluate the effect of aging on the dynamic performance. We report the shift in the resonance frequency.

Frequency Response and Operating Deflection Shape (ODS) Analysis – Evaluating the Operational Behavior

Frequency response and operating deflection shape (ODS) analysis evaluates the vibration behavior of the component or structure under actual operating conditions, providing a realistic assessment of the damping performance and the identification of critical vibration modes.

• Operating deflection shape (ODS) analysis (NTC 5630 – for the operational vibration characterization) – we measure the vibration response of the test specimen (under actual operating conditions or under a simulated operating load) at multiple points using accelerometers. The ODS (the deflection shape at a specific frequency) is calculated. We report the ODS and the vibration amplitude distribution.
• Frequency response function (FRF) measurement under operational loads (NTC 5631 – for the load-dependent response) – we measure the FRF of the test specimen under different operational loads (e.g., different engine speeds, different machine loads) to evaluate the effect of the load on the dynamic response. We report the FRF at each load condition.
• Coherence and noise analysis (NTC 5632 – for the signal quality assessment) – we measure the coherence between the input (force) and the output (acceleration) during the FRF measurement. The coherence indicates the quality of the measurement and the presence of noise or non-linearities. We report the coherence and the noise level.
• Vibration energy distribution analysis (NTC 5633 – for the identification of the dominant modes) – we use the FRF data to calculate the vibration energy distribution over the frequency range. The dominant modes (with the highest energy) are identified. We report the energy distribution and the dominant modes.
• Transient vibration response analysis (NTC 5634 – for the impact and shock response) – we apply a transient load (e.g., an impact or a shock pulse) to the test specimen and measure the time-domain response. The damping ratio and the decay time are determined. We report the decay time and the damping ratio.

Environmental and Aging Effects on Damping Performance – Evaluating Durability

The damping performance of materials can change over time due to thermal aging, UV exposure, chemical attack, and mechanical wear. Our environmental and aging tests evaluate the long‑term stability of the damping properties, ensuring the reliability of the product over its service life in the diverse Croatian climate (coastal, continental, and mountainous).

• Thermal aging effect on damping (ASTM D573 / ISO 188 / NTC 5640 – for the heat‑aged materials) – we age the damping material in an oven at a specified temperature (e.g., 70 °C, 100 °C) for a specified duration (e.g., 7, 14, or 28 days), and then we re‑measure the damping loss factor. We report the change in the loss factor (in %) and the effect of the aging.
• UV aging effect on damping (ASTM G154 / NTC 5641 – for the UV‑exposed materials) – we expose the damping material to UV radiation (UVA‑340) and condensation cycles for a specified duration (e.g., 500 hours), and then we re‑measure the damping loss factor. We report the loss factor after UV exposure and the change.
• Chemical exposure effect on damping (ASTM D471 / NTC 5642 – for the chemically exposed materials) – we immerse the damping material in various chemicals (e.g., mineral oil, 10 % HCl, 10 % NaOH, or a solvent) for a specified duration (e.g., 7 days), and then we re‑measure the damping loss factor. We report the loss factor after chemical exposure and the compatibility.
• Humidity and moisture effect (NTC 5643 – for the moisture‑absorbed materials) – we condition the damping material at a high‑humidity environment (e.g., 40 °C, 95 % RH) for a specified duration (e.g., 7 days), and then we re‑measure the damping loss factor. We report the loss factor after humidity exposure and the moisture uptake.
• Mechanical fatigue effect on damping (NTC 5644 – for the cyclic loading effect) – we subject the damping material to a specified number of mechanical loading cycles (e.g., 10⁶ cycles) and then we re‑measure the damping loss factor. We report the loss factor after fatigue and the change.

Complementary Tests – Hardness, Tensile, and Material Characterization for Damping Correlation

To fully understand the damping performance and to correlate it with the material's properties, we perform complementary tests, including hardness testing, tensile testing, and material characterization.

• Hardness testing (ASTM D2240 / NTC 5650 – Shore A or Shore D for elastomers and polymers) – we measure the Shore A or Shore D hardness of the damping material. The hardness is correlated with the damping loss factor (softer materials generally have higher damping). We report the hardness and the correlation.
• Tensile testing (ASTM D412 / ISO 37 / NTC 5651 – for the tensile strength and elongation) – we perform a tensile test on the damping material to measure the tensile strength (in MPa), the elongation at break (in %), and the tensile modulus (in MPa). The tensile properties are correlated with the damping performance. We report the tensile properties and the correlation.
• Density measurement (ASTM D792 / NTC 5652 – for the material density) – we measure the density of the damping material (in g/cm³) using the Archimedes method. The density is used in the calculation of the specific damping capacity. We report the density.
• Dynamic mechanical analysis (DMA) for the modulus and the damping (ASTM D4065 / NTC 5653 – for the viscoelastic characterization) – we perform a DMA test to measure the storage modulus (E'), the loss modulus (E''), and the damping loss factor (tan δ) as a function of the temperature (from -50 °C to +150 °C) and the frequency. The glass transition temperature (Tg) and the damping peak are identified. We report the DMA curves, the Tg, and the damping peak.
• FTIR spectroscopy (ASTM E168 / NTC 5654 – for the chemical composition and the degradation) – we use FTIR spectroscopy to identify the chemical composition of the damping material and to detect any degradation (e.g., oxidation, chain scission) caused by the aging or the environmental exposure. We report the FTIR spectra and the chemical changes.

Test Report and Recognition in the Croatian Automotive, Industrial, and Construction Sector

All procedures described are within the scope of our ISO/IEC 17025 accreditation, with equipment calibrated periodically (dynamic analyzers, shakers, accelerometers, and thermal chambers) and traceability to international standards (NIST, PTB). Our test reports are issued in English (with a Croatian summary available on request) and include:

• Full identification of the test sample (material, manufacturer, product name, and intended application).
• Detailed description of the test methods applied (ASTM/ISO/SAE/HRN EN/NTC standards, test conditions, frequency, temperature, and amplitude).
• Numerical results: damping loss factor (η), dynamic stiffness (N/mm), transmissibility (%), resonance frequency (Hz), storage modulus (MPa), loss modulus (MPa), and glass transition temperature (Tg).
• Graphical data: loss factor vs. temperature curves, transmissibility vs. frequency curves, and FRF plots.
• Comparative tables against the values specified by the client or against the limits of the relevant standards (ASTM E756, ISO 6721, SAE J1637, HRN EN ISO 6721, and the requirements of the HZN, Ministarstvo gospodarstva, and Državni inspektorat).
• Photographs and micrographs of the test specimens and the test setup.
• Recommendations for material selection, design optimization, and quality control measures to achieve the required damping performance.
• Expanded uncertainty (k=2) for all key measurements, calculated according to the ISO/IEC 98‑3 Guide.

These reports are fully accepted by the Hrvatski zavod za norme (HZN) for the verification of product conformity, by the Ministarstvo gospodarstva i održivog razvoja for industrial and energy compliance, by the Državni inspektorat for market surveillance, and by the Carinska uprava (Croatian Customs) for tariff classification and quality verification in the import of vibration damping materials and components. Additionally, we offer consulting services for the selection of high‑damping materials, the design of vibration‑isolating systems, and the implementation of quality control programs for damping performance, contributing to the reliability, comfort, and safety of products in the diverse and growing Croatian market, from the automotive and aerospace sectors to the industrial machinery and construction industries.