Dynamic compression fatigue testing service

Dynamic Compression Fatigue Testing Service – Comprehensive Evaluation of Foam, Elastomer, Composite and Structural Material Durability Under Cyclic Compressive Loading

As an ISO/IEC 17025 accredited independent testing laboratory, we offer specialised dynamic compression fatigue testing services to manufacturers, engineering contractors, and quality assurance teams across the automotive, aerospace, furniture, bedding, packaging, sports equipment, and construction sectors. Dynamic compression fatigue – the progressive loss of mechanical properties and dimensional stability under repeated compressive loading – is a critical performance parameter for materials and components subjected to cyclic compression, vibration, and impact loading. Our test protocols simulate the dynamic compressive stresses that occur in seating, cushioning, insulation, structural supports, and shock‑absorbing components. All methods are aligned with ISO, ASTM, EN, and GB/T standards, including ISO 3386 (Flexible cellular polymeric materials – Determination of stress‑strain characteristics), ASTM D3574 (Flexible cellular materials – Slab, bonded, and molded urethane foams), ASTM D7774 (Flexural fatigue of plastics), ISO 1856 (Flexible cellular polymeric materials – Determination of compression set), EN 1728 (Furniture – Seating – Test methods), GB/T 6669 (Flexible cellular polymeric materials – Determination of compression set), and GB/T 12825 (Test method for fatigue of flexible cellular materials). Our inspection and test reports are recognised by the National Medical Products Administration (NMPA), the State Administration for Market Regulation (SAMR), the Ministry of Industry and Information Technology (MIIT), and international certification bodies for product registration, type approval, and quality assurance.

Materials and Products We Regularly Test

Our dynamic compression fatigue test facilities accommodate a wide range of material types and finished product forms. Typical test articles include:

Flexible cellular materials (foams) – polyurethane foam, polyethylene foam, polystyrene foam, EVA foam, and rubber foams
Elastomers and rubber materials – natural rubber, SBR, NBR, EPDM, silicone, and polyurethane elastomers
Composite materials – glass fibre reinforced plastics (GFRP), carbon fibre reinforced plastics (CFRP), and sandwich panels
Structural materials – concrete, mortar, masonry, and timber
Packaging materials – cushioning materials, protective packaging, and dunnage
Automotive components – seat cushions, suspension bushings, engine mounts, and bump stops
Furniture and bedding – mattress cores, sofa cushions, and seating systems
Sports equipment – shoe midsoles, protective padding, and impact‑absorbing materials

Test Methods – Constant Amplitude, Step Loading and Variable Amplitude

Constant amplitude dynamic compression fatigue test – ISO 3386 / ASTM D3574 / GB/T 6669 – We apply a cyclic compressive load (sinusoidal waveform) to the test specimen at a specified stress amplitude (or strain amplitude) and a specified frequency (typically 0.5‑5 Hz). The test is performed until a specified number of cycles (typically 10 000‑100 000) is reached, or until the specimen fails (loss of > 20 % of the initial thickness or > 30 % of the initial compressive strength). The thickness reduction (compression set) and the loss of compressive strength are measured at regular intervals during the test.
Step loading fatigue test – for simulating variable service loads – We apply a sequence of different load amplitudes (blocks) in a defined order (e.g., low‑medium‑high‑low) to simulate variable service conditions. The block sequence is repeated until failure or until the specified number of blocks is completed. The cumulative damage (using Miner's rule) is calculated to assess the fatigue life under realistic load spectra.
Variable amplitude (random) compression fatigue test – for simulating random vibration and impact loads – We apply a random compression load (with a defined power spectral density – PSD) to the specimen to simulate the random vibration and impact loads encountered in service (e.g., transportation, off‑road vehicles). The test is performed for a specified duration (e.g., 1‑10 hours).
Temperature‑conditioned dynamic compression fatigue test – for assessing performance at elevated and reduced temperatures – For materials that are used in extreme environments, we perform the dynamic compression fatigue test at elevated temperatures (e.g., 70 °C, 100 °C) or at reduced temperatures (e.g., -20 °C, -40 °C) using a temperature‑controlled chamber. The thickness reduction and the loss of compressive strength are measured at the end of the test.
Combined dynamic compression fatigue and humidity test – for simulating wet and humid service conditions – For materials used in humid environments (e.g., outdoor seating, marine applications), we perform the dynamic compression fatigue test while the specimen is immersed in water (or at a specified humidity level). The test assesses the effect of moisture on the fatigue life and the permanent set.

Specimen Preparation and Conditioning – Ensuring Representative Results

Specimen dimensions – standardised sizes for compression fatigue testing – For foam and elastomeric materials, we prepare cylindrical or prismatic specimens with a height‑to‑thickness ratio of at least 2:1. The specimen dimensions are measured precisely, and the initial thickness is recorded.
Conditioning – ISO 291 / ASTM D618 / GB/T 2918 – Before testing, the specimens are conditioned at the specified temperature (typically 23 °C) and humidity (typically 50 % RH) for a minimum of 48 hours. For foam materials, the conditioning ensures that the material properties are stable at the start of the test.
Displacement measurement – for accurate deformation monitoring – We use a high‑precision LVDT (linear variable differential transformer) to measure the displacement of the specimen during the test. The displacement measurement is accurate to ±0.001 mm.
Load measurement – for accurate force recording and fatigue life determination – We use a calibrated load cell (accuracy ±0.5 %) to measure the compressive force applied to the specimen. The load cell is located in the loading train, between the actuator and the specimen.

Data Analysis and Interpretation – Quantifying Compression Fatigue Performance

Compression set – the permanent deformation after cycling – The compression set is measured at the end of the test (or at specified intervals). It is expressed as a percentage of the original thickness: Compression Set (%) = [(t₀ – t₁) / t₀] × 100, where t₀ is the original thickness and t₁ is the final thickness (after a specified recovery time). A low compression set (< 10 %) indicates good fatigue resistance.
Loss of compressive strength (or modulus) – the reduction in mechanical properties after cycling – We measure the compressive strength (or the compressive modulus) of the specimen before and after the fatigue test. The loss of compressive strength is calculated as: Loss of Strength (%) = [(σ₀ – σ₁) / σ₀] × 100, where σ₀ is the initial compressive strength and σ₁ is the compressive strength after fatigue. A loss of > 30 % is typically considered a failure.
Creep and stress relaxation – the time‑dependent deformation under cyclic loading – During the fatigue test, we record the drift of the load (or the displacement) over time. The creep strain (the increase in strain at constant load) and the stress relaxation (the decrease in stress at constant strain) are quantified.
Fatigue life (Nf) – the number of cycles to failure – for high‑cycle fatigue applications – The fatigue life is the number of cycles to failure (or to a specified degree of degradation). A high fatigue life (e.g., > 100 000 cycles) indicates good resistance to repetitive compressive loading.
S‑N curve (stress‑life curve) – for characterising the fatigue behaviour – We perform dynamic compression fatigue tests at multiple stress amplitudes and plot the stress amplitude (S) versus the number of cycles to failure (Nf) to generate an S‑N curve. The fatigue limit (the stress amplitude that allows infinite life) is determined from the S‑N curve.

Regulatory Compliance and Product Certification – Supporting Industry Standards

Our dynamic compression fatigue testing services are performed in accordance with a wide range of national and international standards. The most commonly requested include:

ISO 3386 – Flexible cellular polymeric materials – Determination of stress‑strain characteristics – for foam materials
ASTM D3574 – Flexible cellular materials – Slab, bonded, and molded urethane foams – for urethane foam testing
ASTM D7774 – Standard Test Method for Flexural Fatigue of Plastics – for flexural fatigue (can be adapted for compression)
ISO 1856 – Flexible cellular polymeric materials – Determination of compression set – for compression set
EN 1728 – Furniture – Seating – Test methods – for seating fatigue
GB/T 6669 – Flexible cellular polymeric materials – Determination of compression set – the Chinese national standard for compression set
GB/T 12825 – Test method for fatigue of flexible cellular materials – the Chinese national standard for fatigue testing of foams
ASTM D695 – Standard Test Method for Compressive Properties of Rigid Plastics – for compressive properties (can be used as a reference for fatigue testing)

Report Acceptance and Regulatory Recognition

All dynamic compression fatigue tests are conducted under our ISO/IEC 17025 accreditation, using calibrated fatigue testers, environmental chambers, and instrumentation, all traceable to national and international reference standards. Our final test reports include: a complete description of the test article (material, dimensions, manufacturer), the test method and conditions (load amplitude, frequency, temperature, humidity), the measured parameters (compression set, loss of strength, fatigue life, S‑N curve), a statistical summary (mean, standard deviation, coefficient of variation), and a clear pass/fail verdict against your specified acceptance criteria. These reports are accepted by the National Medical Products Administration (NMPA), the State Administration for Market Regulation (SAMR), the Ministry of Industry and Information Technology (MIIT), and international certification bodies for product registration, type approval, and quality assurance. Bilingual (English/Chinese) versions are available to facilitate submissions to domestic and international authorities and to support your global market access.