What Is Elongation?
Elongation at break test is a measurement in which the increase in the measurement length of the sample at the moment of breaking during the tensile test is determined as a percentage as the ratio of the initial dimension length.
Purpose of Elongation
The goal is to determine the elastic capacity of the elastomer and monitor its loss after aging or chemical exposure.
Which Products Is Elongation Applied To?
- Gaskets and sealing elements
- Elastomer profiller
- Hoses and bellows
- rubber coatings
In Which Sectors Is Elongation Used?
Standards Related to Elongation
- ISO 37
- ASTM D412
- ISO 23529
Elongation Conditions
- Measurement
- Measurement length with extensometer; gauge length is used instead of jaw separation
- Tensile speed
- Defined in standard
- Conditioning
- according to ISO 23529
- Reporting
- In percentage; median or mean
Equipment for Elongation
- Calibrated tensile testing machine
- Optical or contact extensometer
- sample cutting die
- Conditioning room
Sample Requirements for Elongation
- Sample edges must be flawless
- Size markings must be clear
- The sliding jaw must hold the sample without nicking it
- The number of specimens is defined in the standard
Duration of Elongation
Typically 2–4 days including conditioning.
Elongation Procedure
- 1Samples are cut, marked and conditioned.
- 2The extensometer is fitted.
- 3Pulling is applied at a defined speed.
- 4The elongation at break is recorded.
- 5Percentage elongation is calculated and reported.
Elongation Acceptance Criteria
The acceptance criterion is the minimum breaking elongation value given in the specification.
Evaluation of Results
The elongation calculated from jaw separation differs from the actual elongation due to jaw displacement; It requires measurement based on standard size. Loss of elongation after aging is one of the most sensitive indicators of rubber degradation.
Elongation Report
- Standard applied
- Measurement method (extensometer)
- Conditioning and speed
- Elongation at break values
- Fracture location
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 product specifications
Otomotiv Testleri — What Does This Testing Field Cover?
The section below describes the field that the Elongation 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.
Automotive testing shows that a component keeps working under conditions representing the loads it will meet over the life of the vehicle. A vehicle is not a single product but an ENVIRONMENT: vibration, temperature cycling, salt water, stone impact, electrical transients and electromagnetic noise are all present at the same time and for years.
What distinguishes this family is that VEHICLE MANUFACTURER SPECIFICATIONS sit on top of the standards. ISO and SAE publications establish the common ground; but Volkswagen, BMW, Ford, Stellantis, Toyota and Renault define different severity levels, additional tests and different acceptance criteria in their own specifications. For a component, the phrase "complies with automotive standards" is not sufficient on its own; which manufacturer's specification, and which revision of it, must be answered.
The family carries three separate processes together and they are often confused. Homologation covers the type approvals a vehicle needs to enter traffic and runs under state authority. Supplier approval means passing the vehicle manufacturer's own quality and testing requirements and is a commercial relationship. The third is design verification: the engineering team demonstrating that its own design meets its targets.
At component level the test plan is built around the LOCATION OF USE. A module in the engine bay and a module in the boot do not go through the same temperature and vibration profile; a component inside a door and one in the roof console do not see the same water and dust exposure. The ISO 16750 series is the common framework for this location-based approach.
The shift to electric vehicles has reshaped the field. High-voltage safety, insulation coordination, battery safety, charging interface conformity and the electromagnetic behaviour of high-voltage components have been added to the classical automotive test set. In a quiet vehicle, acoustic and vibration expectations have changed too; sounds once masked by the combustion engine are now audible.
The quality system side cannot be separated from testing in this field. A manufacturer under IATF 16949 presents test results in the PPAP file; measurement system analysis, process capability study and the control plan stand around the test report. A single good result is not enough — the process must be shown to be able to repeat it.
Method groups in this field
Environmental and climatic
Temperature cycling, thermal shock, damp heat, salt spray, dust and water ingress (IP), solar radiation. Severity levels vary with the mounting location.
Mechanical
Sine and random vibration, shock, mechanical loads, fastener torque and durability cycles.
Electrical
Supply voltage variations, transients (ISO 7637), reverse polarity, overvoltage, short circuit and sleep current measurements.
EMC
Component emissions (CISPR 25), radiated and conducted immunity (ISO 11452 series), electrostatic discharge (ISO 10605).
Materials and emissions
Odour, fogging and VOC emissions from interior materials; flammability; UV ageing; coating durability and stone impact.
Functional safety and cyber security
Functional safety evidence under ISO 26262 and cyber security engineering under ISO/SAE 21434; these are tied to regulation through UNECE R155 and R156.
Commonly confused in this field
- An automotive report without a specification reference is not accepted in the supply chain; which OEM specification and revision was applied must be stated.
- Type approval and supplier approval are different processes. A component with E-Mark approval is not thereby considered to have passed the OEM's own acceptance tests.
- A result obtained on a prototype does not carry over to series production; PPAP is done with series production parts.
- On the EMC side, measuring emissions alone is incomplete; immunity is a separate body of work and is more critical in a vehicle.
- On electric vehicle components, high-voltage safety is a distinct competence; classical 12 V test infrastructure is not sufficient.
Which decisions these results support
- Supplier component approval and the PPAP file
- UNECE type approval and E-Mark marking
- Design verification and durability evidence
- Root cause analysis of field complaints and warranty returns
- Assessing the impact of a design or supplier change
Related Tests
Frequently Asked Questions About Elongation
According to which standard is Elongation made?
Elongation is executed in scope ISO 37, ASTM D412 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 Elongation apply to?
Mainly applied to Gaskets and sealing elements, Elastomer profiller, Hoses and bellows and rubber coatings. Whether your product is included in the scope is determined by examining its technical specifications and intended use.
Under what conditions is Elongation done?
The determining parameters are: Measurement — Measurement length with extensometer; gauge length is used instead of jaw separation, Tensile speed — Defined in standard and Conditioning — according to ISO 23529. 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 Elongation?
Sample edges must be flawless, Size markings must be clear and The sliding jaw must hold the sample without nicking it. The number of samples is determined according to the product standard and the scope to be reported.
How long does Elongation take?
Typically 2–4 days including conditioning. 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 Elongation result called "appropriate"?
The acceptance criterion is the minimum breaking elongation value given in the specification.