Durability testing service

Durability Testing Service – Accredited ISO/IEC 17025 Long‑Term Performance and Reliability Assessment for the Croatian Market

Durability testing is a critical mechanical and environmental evaluation method used to assess the ability of materials, components, and systems to withstand prolonged exposure to operational stresses, environmental conditions, and cyclic loading without experiencing premature failure, degradation, or loss of function. This testing is essential for ensuring the safety, reliability, and economic efficiency of products used in the automotive, aerospace, construction, energy, medical device, consumer goods, and industrial machinery sectors. In the Croatian market, where the Hrvatski zavod za norme (HZN), the Ministarstvo gospodarstva i održivog razvoja, the Državni inspektorat, the Hrvatska regulatorna agencija za mrežne djelatnosti (HAKOM), and the Carinska uprava enforce strict quality, safety, and environmental standards aligned with EU directives and HRN EN (Croatian standards based on European norms), the accurate evaluation of durability is essential for product certification, supplier qualification, type testing, quality control in manufacturing, and import‑export processes. Our laboratory offers a comprehensive durability testing service, applying standardized methods that simulate long‑term service conditions, including mechanical fatigue, thermal cycling, environmental exposure, chemical attack, and wear, to predict service life and to verify the design margins. 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.

Test Samples and Components We Regularly Examine

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

• Automotive and transportation components – suspension systems, steering components, brake parts, engine mounts, and exhaust systems.
• Construction and infrastructure materials – structural steel, concrete, paving stones, roofing materials, and waterproofing membranes.
• Industrial machinery and equipment parts – gears, bearings, shafts, pumps, valves, and conveyor components.
• Consumer goods and appliances – furniture, hinges, sliding mechanisms, and electronic enclosures.
• Medical devices and implants – orthopaedic implants, surgical instruments, and drug‑delivery systems.
• Aerospace and defense components – airframe structures, landing gear, actuators, and avionics housings.
• Prototype and new designs – submitted by manufacturers for validation of durability before series production.
• Field‑retrieved components – for failure analysis and remaining life assessment.

Mechanical Fatigue Testing – Evaluating Resistance to Cyclic Loading

Mechanical fatigue testing is one of the most important durability evaluation methods. It assesses the ability of a material or component to withstand repeated cyclic loading without failure, simulating the real‑world stress cycles encountered during operation. Our tests follow international standards and the requirements of the Croatian automotive, aerospace, and industrial sectors.

• Constant amplitude fatigue test (ASTM E466 / ISO 1099 / NTC 5200 – for metals and alloys) – we apply a sinusoidal cyclic load (tension‑compression, bending, or torsion) at a specified stress amplitude and frequency (e.g., 10‑50 Hz) until the specimen fails or until a specified number of cycles (e.g., 10⁷ cycles) is reached. The S‑N curve (stress vs. cycles to failure) is constructed. We report the fatigue limit, the number of cycles to failure, and the failure mode.
• Variable amplitude fatigue test (NTC 5201 – for simulating real‑world load spectra) – we apply a load sequence that simulates the actual load spectrum of the component (e.g., based on field‑measured data or a standardized spectrum). The cumulative damage is calculated using the Palmgren‑Miner rule. We report the predicted service life and the cumulative damage.
• Fatigue test at elevated temperatures (NTC 5202 – for high‑temperature applications) – we perform the fatigue test at a specified elevated temperature (e.g., 100 °C, 200 °C, 500 °C) to evaluate the effect of temperature on the fatigue life. We report the S‑N curve and the fatigue limit at the elevated temperature.
• Fatigue test under corrosive environment (NTC 5203 – for corrosion‑fatigue assessment) – we perform the fatigue test in a corrosive environment (e.g., salt spray, acidic solution, or humid air) to evaluate the combined effect of cyclic loading and corrosion. We report the corrosion‑fatigue life and the failure mechanism.
• High‑cycle fatigue (HCF) and low‑cycle fatigue (LCF) testing (NTC 5204 – for different life regimes) – we perform fatigue tests in the high‑cycle regime (stress‑controlled, > 10⁴ cycles) and in the low‑cycle regime (strain‑controlled, < 10⁴ cycles). We report the S‑N curve and the strain‑life curve.

Thermal Cycling and Thermal Shock Testing – Evaluating Resistance to Temperature Variations

Thermal cycling and thermal shock testing evaluate the ability of a material or component to withstand rapid or gradual temperature changes without cracking, delamination, or degradation. These tests are essential for products that are exposed to fluctuating temperatures, such as automotive exhaust systems, electronic enclosures, and building materials.

• Thermal cycling test (IEC 60068‑2‑14 / NTC 5210 – for electronic and mechanical components) – we subject the test item to repeated temperature cycles (e.g., from -20 °C to +80 °C) with a specified ramp rate (e.g., 2 °C/min) and dwell time (e.g., 30 minutes) for a specified number of cycles (e.g., 100, 500, or 1000 cycles). We inspect the item for cracking, delamination, and loss of function after the cycling. We report the temperature range, the number of cycles, and the condition of the item.
• Thermal shock test (IEC 60068‑2‑14 / NTC 5211 – for rapid temperature changes) – we rapidly transfer the test item between two temperature chambers (e.g., a hot chamber at +100 °C and a cold chamber at -20 °C) with a transfer time of less than 10 seconds, for a specified number of cycles (e.g., 50 cycles). We inspect the item for damage. We report the temperature extremes, the number of cycles, and the condition of the item.
• Thermal cycling with mechanical load (NTC 5212 – for combined thermal and mechanical stress) – we apply a mechanical load (e.g., a tensile or a bending load) to the test item during the thermal cycling, to simulate the combined effect of thermal expansion and mechanical stress. We report the condition of the item and the failure mode.
• Thermal cycling for building materials (NTC 5213 – for construction and infrastructure) – we subject building materials (e.g., concrete, asphalt, roofing) to thermal cycles that simulate the seasonal temperature variations in the Croatian climate (continental, coastal, and mountainous). We report the dimensional changes, the cracking, and the loss of strength.
• Thermal imaging during thermal cycling (NTC 5214 – for detecting hot spots and delamination) – we use an infrared camera to monitor the temperature distribution on the test item during the thermal cycling, to detect localized overheating (hot spots) and delamination (which causes a thermal resistance change). We report the thermal images and the hot‑spot locations.

Environmental and Weathering Durability Testing – Simulating Real‑World Conditions

Environmental and weathering durability testing evaluates the resistance of materials to the effects of UV radiation, humidity, salt spray, and chemical attack. These tests are essential for products that are exposed to outdoor conditions, especially in the diverse Croatian climate (coastal, continental, and mountainous).

• UV and xenon arc weathering test (ASTM G154 / ISO 4892‑3 / NTC 5220 – for outdoor exposure) – we expose the test item to UV radiation (UVA‑340) and condensation cycles in a weathering chamber for a specified duration (e.g., 500, 1000, or 2000 hours). We measure the change in color (ΔE*), the loss of gloss, and the loss of mechanical properties. We report the UV resistance and the property retention.
• Salt spray test (ASTM B117 / ISO 9227 / NTC 5221 – for corrosion resistance) – we expose the test item to a continuous 5 % NaCl salt spray at 35 °C for a specified duration (e.g., 240, 500, or 1000 hours). We inspect for rust, pitting, blistering, and loss of adhesion. We report the corrosion rating (ASTM D610) and the condition of the specimen.
• Humidity and condensation test (ASTM D2247 / ISO 6270‑2 / NTC 5222 – for moisture resistance) – we expose the test item to a condensing humidity environment (40 °C, 95 % RH) for a specified duration (e.g., 7, 14, or 28 days). We inspect for blistering, discoloration, and loss of adhesion. We report the condition and the rating.
• Chemical resistance test (ASTM D543 / NTC 5223 – for oil, acid, and solvent resistance) – we immerse the test item in various chemicals (e.g., mineral oil, 10 % HCl, 10 % NaOH, gasoline) at a controlled temperature for a specified duration (e.g., 7 days). We measure the change in mass, the loss of adhesion, and the change in mechanical properties. We report the chemical resistance and the compatibility with the test chemicals.
• Combined environmental test (NTC 5224 – for simulating tropical and coastal conditions) – we subject the test item to a combined cycle of UV exposure, salt spray, humidity, and temperature cycling to simulate the harsh conditions of the Croatian coastal and tropical regions. We report the overall degradation and the service life prediction.

Abrasion, Wear, and Erosion Testing – Evaluating Surface Durability

Abrasion, wear, and erosion are major causes of surface degradation and functional loss in many components. Our tests measure the resistance of materials to surface wear, abrasive particles, and fluid erosion, which are essential for the durability of components used in mining, construction, agriculture, and material handling.

• • Taber abrasion test (ASTM D4060 / NTC 5230 – for coatings and plastics) – we use a Taber abraser with abrasive wheels (e.g., CS‑17) to abrade the test surface for a specified number of cycles (e.g., 1000 cycles). We measure the weight loss (in mg) and the number of cycles to the substrate exposure. We report the weight loss and the abrasion resistance.
  • Dry sand / rubber wheel abrasion test (ASTM G65 / NTC 5231 – for metals and alloys) – we use a dry sand / rubber wheel abrasion tester to simulate the abrasive wear caused by soil, sand, and mineral particles. We measure the weight loss (in g) and the volume loss (in mm³). We report the wear rate (in mm³/N·m) and the abrasion resistance.
  • Pin‑on‑disk wear test (ASTM G99 / NTC 5232 – for evaluating the friction and wear) – we use a pin‑on‑disk tribometer to measure the coefficient of friction and the wear rate of the test material against a specified counter‑material (e.g., steel ball, ceramic pin). We report the friction coefficient (μ) and the wear rate (in mm³/N·m).
  • Erosion test by solid particle impingement (ASTM G76 / NTC 5233 – for evaluating the erosion resistance) – we use a gas‑jet erosion tester to direct a stream of abrasive particles (e.g., silica sand) at the test surface at a controlled velocity and impingement angle. We measure the mass loss and the erosion rate. We report the erosion rate (in mg/kg) and the erosion resistance.
  • Wear test at elevated temperatures (NTC 5234 – for high‑temperature wear resistance) – we perform the wear test at a specified elevated temperature (e.g., 100 °C, 300 °C) to evaluate the effect of temperature on the wear resistance. We report the wear rate at the elevated temperature and the temperature derating.

Accelerated Life Testing – Predicting Service Life under Accelerated Conditions

Accelerated life testing (ALT) and highly accelerated life testing (HALT) are used to identify failure modes and to predict the service life of products in a shorter time by subjecting them to higher‑than‑normal stress levels. These tests are essential for the rapid validation of design changes and for the estimation of the product warranty.

• Accelerated life test (ALT) – NTC 5240 – for failure mode identification – we apply elevated stress levels (e.g., higher temperature, higher load, higher voltage) to the test item to accelerate the aging process. The failure time is recorded, and the failure modes are identified. The data is used to extrapolate the service life under normal conditions using the Arrhenius model or other acceleration models. We report the acceleration factor and the predicted service life.
• Highly accelerated life test (HALT) – NTC 5241 – for robustness evaluation – we subject the test item to progressively increasing stress levels (temperature, vibration, voltage) until failure occurs. The operating limits and the destructive limits are determined. We report the operating limits, the destructive limits, and the design margins.
• Step‑stress accelerated life test (NTC 5242 – for estimating the life distribution) – we apply stress in steps (e.g., increasing temperature by 10 °C every 100 hours) and record the failure times. The life distribution is estimated using the Weibull model. We report the Weibull parameters (β and η) and the B10 life (the life at which 10 % of the population fails).
• Accelerated aging test for polymers (ASTM D573 / ISO 188 / NTC 5243 – for thermal aging) – we age the polymer material at elevated temperatures (e.g., 70 °C, 100 °C, 150 °C) for specified durations (e.g., 7, 14, 28 days) and measure the changes in the mechanical properties (tensile strength, elongation, hardness). The service life is predicted using the Arrhenius model. We report the property retention and the predicted life.
• Accelerated environmental test (NTC 5244 – for combined UV, humidity, and thermal stress) – we subject the test item to a combined accelerated environmental stress (UV, humidity, and temperature) for a specified duration, and we evaluate the degradation. The acceleration factor is determined. We report the degradation and the service life prediction.

Complementary Tests – Material Characterization and Failure Analysis

To fully understand the durability performance and to identify the root cause of any failure, we perform complementary tests, including material characterization, microstructural analysis, and failure analysis. These tests are essential for design improvement and for certification by the HZN and other Croatian authorities.

• Microstructural examination (ASTM E3 / NTC 5250 – for metals, polymers, and composites) – we examine the microstructure of the material (grain size, phase distribution, porosity, and inclusions) before and after the durability test, to identify any changes (e.g., grain growth, phase transformation, or micro‑cracking). We report the microstructural observations and the changes.
• Scanning electron microscopy (SEM) and EDS – ASTM E1508 / NTC 5251 – for fracture and wear surface analysis – we use SEM to examine the fracture surfaces and the wear surfaces to identify the failure mechanisms (e.g., fatigue, brittle fracture, ductile fracture, adhesive wear, or abrasive wear). EDS is used to detect the presence of corrosion products or contamination. We report the SEM images, the EDS spectra, and the failure mechanism.
• X‑ray diffraction (XRD) – ASTM E1857 / NTC 5252 – for phase analysis – we use XRD to analyze the crystal structure of the material and to identify any phase transformations that may have occurred during the durability test (e.g., the formation of oxides or carbides). We report the phase composition and the changes.
• Hardness and microhardness testing (ASTM E18 / NTC 5253 – for evaluating the material degradation) – we measure the hardness (Rockwell, Brinell, or Vickers) of the material in the damaged and undamaged areas, to detect any work hardening, softening, or embrittlement. We report the hardness values and the change in hardness.
• Thermal analysis (TGA and DSC – ASTM E1131 / NTC 5254 – for polymers and composites) – we use thermogravimetric analysis (TGA) to measure the thermal stability and the decomposition temperature of the material, and differential scanning calorimetry (DSC) to measure the glass transition temperature (Tg). We report the decomposition temperature, the mass loss, and the Tg.

Test Report and Recognition in the Croatian Industrial and Manufacturing Sector

All procedures described are within the scope of our ISO/IEC 17025 accreditation, with equipment calibrated periodically (fatigue test machines, thermal chambers, wear testers, environmental chambers, SEM, etc.) 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 item (product name, model, serial number, material, and intended application).
• Detailed description of the test methods applied (ASTM/ISO/IEC/HRN EN/NTC standards, test conditions, and stress levels).
• Numerical results: fatigue life (cycles), thermal cycling resistance (cycles), corrosion resistance (hours), wear rate (mm³/N·m), and predicted service life (years).
• Graphical data: S‑N curves, temperature‑time curves, degradation curves, and Weibull plots.
• Comparative tables against the values specified by the client or against the limits of the relevant standards (HRN EN, ISO, ASTM, and the requirements of the HZN, Ministarstvo gospodarstva, and Državni inspektorat).
• Photographs and micrographs (SEM, optical) of the test item before and after the test, showing the failure mode, the wear pattern, and the microstructural changes.
• Recommendations for design improvement, material selection, and quality control measures to enhance the durability and the service life.
• 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 material compliance and energy efficiency, by the Državni inspektorat for market surveillance, by the Hrvatska regulatorna agencija za mrežne djelatnosti (HAKOM) for equipment used in the power grid and telecommunications, and by the Carinska uprava (Croatian Customs) for tariff classification and quality verification in the import of durable goods and components. Additionally, we offer consulting services for the design of durable products, the selection of materials with high fatigue and wear resistance, and the implementation of reliability improvement programs, contributing to the safety, reliability, and economic efficiency of industrial products and infrastructure in the diverse and growing Croatian market, from the automotive and aerospace sectors to the construction, energy, and consumer goods industries.