Fatigue

The furniture fatigue test repeats, many times, a force on components and joints that stays below the breaking load. A load that causes no damage in a single application can initiate and propagate a crack when repeated enough times. The test reveals this cumulative damage.

The purpose is to identify the product's weak joint and the area that fails first. Fatigue damage usually occurs suddenly and without warning; catching it in the laboratory prevents field failure.

• Chair leg and backrest joints
• Folding and moving mechanisms
• Table leg joints
• Metal profiles and welded frames
• Office chair gas columns and castor assemblies

• TS EN 1728 (seating — cyclic loading tests)
• TS EN 1730 (tables — cyclic loading)
• TS EN 16139 (non-domestic seating — requirements)
• TS EN 1335-3 (office work chairs — test methods)

Load level

Defined in the product standard; below the breaking load

Number of cycles

From the product standard; by use class

Frequency

Defined in the method standard; at a rate that will not heat the material

• Cyclic loading test rigs
• Load cells and cycle counter
• Deformation measurement systems
• Magnifier for crack inspection, and dye penetrant if needed

• Fully assembled product, or a component defined in the standard
• Welded joints must be as produced
• The test is destructive
• The declared use class must be provided

Duration is determined by the number of cycles and application frequency; high-cycle programmes take days or weeks.

1. 1The product is assembled, conditioned and mounted on the rig.
2. 2Initial measurements and visual inspection are performed.
3. 3The defined load is repeated at the defined frequency.
4. 4Crack and loosening checks are performed at interim stages.
5. 5If damage occurs, the cycle count is recorded.
6. 6If the target cycle count is completed, the product is examined one final time.

The acceptance criterion is no cracking, breakage or loss of function at the end of the target cycle count. The method standard defines how the force is applied, not how much. Force levels and cycle counts come from the product standard (such as EN 12520, EN 12521, EN 14749, EN 527) or from the contract; different levels are defined for domestic, office and contract use.

The location of the first damage is design feedback: a crack starting at a weld seam points to seam geometry, one starting at a screw area points to a weak cross-section. Recording the damage cycle allows comparison before and after a design change.

• Product and component identification
• Method, load and frequency applied
• Number of cycles completed
• If damage occurs, its location, type and starting cycle
• Photographs

EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.

Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.

• EU 2001/95/EC General Product Safety Directive
• Regulation on the General Safety of Products
• Requirements of product standards such as EN 12520 / EN 1730

The section below describes the field that the Fatigue test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.

• Strength
• Stability
• Durability
• Surface Resistance
• Load Test
• Bunk Bed Safety
• Chair Test
• Table Test
• Cabinet Test
• Impact
• Flammability
• Formaldehyde