What Is Rebound?
The rebound elasticity test is a test in which elasticity is determined as a percentage as the ratio of the height to which a standard pendulum rebounds after hitting the sample to its initial height.
Purpose of Rebound
The aim is to comparatively determine the damping and energy return behavior of the elastomer.
Which Products Is Rebound Applied To?
- Vibration damping elements
- Rubber sole materials
- Strap and buffer materials
- Mixture development samples
In Which Sectors Is Rebound Used?
Standards Related to Rebound
- ISO 4662
- ASTM D7121
- ISO 23529
Rebound Conditions
- Instrument
- Standard pendulum (Lüpke or Schob type)
- Specimen thickness
- Defined in standard
- Temperature
- Defined in the specification; varies significantly with temperature
- front impact
- Measurements are taken after a number of front impacts defined in the standard.
Equipment for Rebound
- Rebound elasticity pendulum
- Temperature controlled sample holder
- Thickness measuring instrument
- Conditioning room
Sample Requirements for Rebound
- Sample thickness and surface must comply with the standard
- The sample must be fully supported
- The number of pre-impacts must be observed
- The temperature must be recorded at the time of measurement
Duration of Rebound
Typically 1–2 days.
Rebound Procedure
- 1The sample is conditioned and its thickness is measured.
- 2The sample is placed in the holder.
- 3A defined number of pre-impacts are made.
- 4Measurement bumps are applied and rebound heights are read.
- 5The percentage of elasticity is calculated.
- 6It is reported along with the temperature.
Rebound Acceptance Criteria
The acceptance criterion is the rebound elasticity range given in the specification.
Evaluation of Results
Rebound elasticity is strongly dependent on temperature; The value given without specifying the temperature cannot be compared. If preliminary impacts are omitted, initial readings are systematically different.
Rebound Report
- Applied standard and device type
- Specimen thickness
- Temperature
- Number of pre-impacts
- Rebound elasticity values
Accreditation
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.
Scope and authorisationsRelated Regulations
- Material and mixture specifications
Rubber Testing — What Does This Testing Field Cover?
The section below describes the field that the Rebound 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.
Rubber testing determines the mechanical behaviour of an elastomer and its resistance to environmental effects. Elastomers are assessed with a different logic from metals and plastics: the real question is not strength but ELASTIC RECOVERY and ageing behaviour.
The function of an elastomer is usually to deform and return: a gasket is compressed and provides a seal, a mount absorbs vibration, a hose expands under pressure. What is measured in the field is therefore not "how many newtons does it withstand" but "how far does it recover after deformation, and how long does it keep doing so".
COMPRESSION SET is therefore the most decisive measurement in the field. If a gasket cannot recover after being held compressed for a long period, it has lost its sealing function even though it has not torn at all. This measurement is made together with temperature, because permanent set increases rapidly with temperature.
Hardness is the most common measurement in the field, using the Shore A and IRHD scales. It is fast and practical but does not define the material on its own: two different compounds of the same hardness can show completely different ageing and fluid resistance. Hardness is valuable in monitoring compound consistency.
On the environmental resistance side, hot air ageing, swelling in fluids, ozone cracking and low temperature behaviour are examined. FLUID RESISTANCE is particularly critical: the same elastomer behaves differently in fuel, oil, coolant and brake fluid — swelling in one, shrinking in another, hardening in a third. The material is therefore tested with the actual fluid it will contact and at the actual temperature.
Ozone cracking is a silent cause of failure in parts used outdoors. Low concentrations of ozone in the atmosphere create surface cracks in unsaturated elastomers under strain; the part cracks while appearing to carry no load at all. An ozone chamber accelerates and reveals this behaviour.
Low temperature behaviour is the second silent risk. As an elastomer approaches its glass transition temperature it loses elasticity and behaves like a rigid plastic; a gasket starts to leak in the cold. Low temperature recovery and brittleness tests establish this limit.
A change of compound is not a silent change in this family. When filler content, plasticiser or the vulcanisation system changes, mechanical properties and fluid resistance shift together; verification is repeated.
Method groups in this field
Mechanical
Tensile stress-strain properties, tear strength, abrasion (rotating drum and Pico), fatigue and tear propagation.
Hardness
Shore A and IRHD indentation hardness; a rapid indicator of compound consistency.
Permanent deformation
Compression set and stress relaxation; decisive for sealing components.
Fluid resistance
Swelling in fuel, oil, coolant and chemicals, change in mass and volume, loss of hardness and strength.
Ageing
Hot air ageing, ozone cracking, the effects of UV and humidity.
Low temperature
Low temperature recovery, brittleness temperature and flexibility measurements.
Commonly confused in this field
- Hardness does not define the material; two compounds of the same hardness can show different ageing and fluid resistance.
- Fluid resistance must be tested with the actual fluid and the actual temperature; a general claim of oil resistance is insufficient.
- Without measuring compression set, no decision can be made about sealing life.
- Ozone cracking occurs under strain; a test with an unstrained specimen does not show the real risk.
- A change of compound requires verification to be repeated; a supplier may change its compound silently.
- A gasket whose low temperature behaviour is not stated produces unexpected leaks in cold climates.
Which decisions these results support
- Material selection for gaskets and sealing components
- Automotive and industrial component approval
- Verification of a compound change
- Root cause analysis of field leaks and cracking
- Declaration of the operating temperature range and fluid compatibility
Related Tests
Frequently Asked Questions About Rebound
According to which standard is Rebound made?
Rebound is executed in scope ISO 4662, ASTM D7121 and ISO 23529. The limit values and acceptance criteria to be applied are defined in the product standard; The version valid for your product is confirmed in writing at the offer stage.
Which products does Rebound apply to?
Mainly applied to Vibration damping elements, Rubber sole materials, Strap and buffer materials and Mixture development samples. Whether your product is included in the scope is determined by examining its technical specifications and intended use.
Under what conditions is Rebound done?
The determining parameters are: Instrument — Standard pendulum (Lüpke or Schob type), Specimen thickness — Defined in standard and Temperature — Defined in the specification; varies significantly with temperature. The full terms are in the "Test Conditions" section on the page and vary depending on the product standard.
What kind of sample is needed for Rebound?
Sample thickness and surface must comply with the standard, The sample must be fully supported and The number of pre-impacts must be observed. The number of samples is determined according to the product standard and the scope to be reported.
How long does Rebound take?
Typically 1–2 days. This duration belongs to the experiment itself; sample preparation, queuing and reporting are also evaluated. A realistic schedule for your product is given in the offer.
What is the Rebound result called "appropriate"?
The acceptance criterion is the rebound elasticity range given in the specification.