What Is Torsion Test?
The torsion test is a test in which torque is applied to a specimen about its axis while the torque–rotation-angle relationship is measured. It enables evaluation of shear modulus, torsional strength and ductility.
Purpose of Torsion Test
The purpose is to determine the strength and deformation capacity of torque-transmitting parts, and to check ductility in wire and fasteners.
Which Products Is Torsion Test Applied To?
- Wire and rod
- Shafts and drivetrain components
- Fasteners
- Spring materials
In Which Sectors Is Torsion Test Used?
Standards Related to Torsion Test
- ISO 7800
- ASTM E143
- ISO 898-7
Torsion Test Conditions
- Rotation speed
- Constant angular speed per the standard
- Gauge length
- Free length defined in the standard according to specimen diameter
- Temperature
- Room temperature, or per the specification
Equipment for Torsion Test
- Torsion testing machine
- Torque transducer
- Angle meter (goniometer)
- Specimen-mounting grips
Sample Requirements for Torsion Test
- The specimen must be regular and undamaged
- Free length is set according to the standard
- Generally three specimens per set
Duration of Torsion Test
Testing per specimen is short; a set is completed within half a working day.
Torsion Test Procedure
- 1Specimen diameter and free length are measured.
- 2The specimen is mounted axially in the grips.
- 3Torque is applied at the defined rate; torque and rotation angle are recorded.
- 4Loading continues to fracture or the specified number of rotations.
- 5The fracture surface and number of rotations are evaluated.
Torsion Test Acceptance Criteria
The acceptance criterion is defined in the specification as a minimum torque, minimum number of rotations, or minimum shear strength.
Evaluation of Results
The torque–angle curve, breaking torque and the appearance of the fracture surface are evaluated together. A brittle fracture surface indicates a lack of ductility.
Torsion Test Report
- Standard applied
- Specimen diameter and free length
- Breaking torque and number of rotations
- Torque–angle curve
- Fracture-surface assessment
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
- Fastener product standards
Mekanik Testler — What Does This Testing Field Cover?
The section below describes the field that the Torsion Test 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.
Mechanical testing measures how a material or a part behaves under force. The family ranges from static loading (tension, compression, bending) to time-dependent behaviour (fatigue, creep), and from hardness and wear to fracture toughness.
What these tests have in common is that the result is reported as a MATERIAL PROPERTY. Yield strength or hardness is not a conformity decision; it is numerical data against which the design and the product standard will compare. Mechanical test reports are therefore usually an input to an engineering decision rather than to a product approval — material selection, safety factor, life prediction.
The distinction between static and dynamic behaviour is the key to understanding the field. A part may appear entirely unstressed under a static load yet break under repeated loading; fatigue fracture occurs at stresses well below the yield strength and gives no warning. For rotating, vibrating or cyclically loaded parts, a tensile test alone is therefore not sufficient evidence.
Test conditions determine the result, and this is critical for the readability of the report: specimen geometry, loading rate, temperature, conditioning and the gripping arrangement. The same material gives different values under different conditions. In plastics the rate effect is very pronounced, in metals the temperature effect; in composites the specimen orientation changes the result entirely.
Hardness is the most misused measurement in the field. Because it is fast, close to non-destructive and inexpensive, it is often used in place of strength. Conversion tables from hardness to strength exist, but they are APPROXIMATE and depend on the material group; using them as the sole evidence in material acceptance is wrong.
The fracture mechanics side requires a specific competence. Fracture toughness and fatigue crack growth rate measurements make it possible to calculate how long a cracked structure will last; they are the basis of damage-tolerant design in fields such as pressure equipment, aircraft structures and pipelines.
Method groups in this field
Static tests
Tension, compression, bending, shear and torsion. Yield and tensile strength, elongation and modulus of elasticity are obtained.
Impact tests
Charpy and Izod notch impact; the brittle-to-ductile transition behaviour of the material is determined as a function of temperature.
Hardness
Brinell, Vickers, Rockwell, Shore and micro hardness. Valuable for surface treatment depth and local differences in strength.
Fatigue
Force- and strain-controlled axial fatigue, fatigue in bending; S-N curves and the endurance limit.
Creep and stress relaxation
Behaviour under long-term load at high temperature; decisive for boiler, turbine and pressure equipment materials.
Fracture mechanics
Plane-strain fracture toughness, the J integral, CTOD and fatigue crack growth rate.
Wear and friction
Taber and rotating drum abrasion, coefficient of friction measurements.
Commonly confused in this field
- Calculating strength from hardness is approximate; it cannot be used as the sole evidence in material acceptance.
- Adequate static strength does not demonstrate fatigue strength; a cyclically loaded part requires a separate test.
- If test rate and temperature are not reported, the result cannot be compared — especially for polymers and composites.
- A test specimen and the actual part may not give the same value; moulding orientation, weld lines and differences in surface treatment all have an effect.
- A strength value given for a composite without stating the specimen orientation is meaningless.
- ASTM and ISO counterparts measure the same quantity but use different specimen geometries; the results are not treated as directly equivalent.
Which decisions these results support
- Design verification and material selection
- Incoming material control and supplier approval
- Meeting the mechanical requirements of the product standard
- Failure analysis, life prediction and damage tolerance calculation
- Verifying heat treatment and surface treatment processes
Related Tests
Frequently Asked Questions About Torsion Test
According to which standard is Torsion Test made?
Torsion Test is executed in scope ISO 7800, ASTM E143 and ISO 898-7. 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 Torsion Test apply to?
Mainly applied to Wire and rod, Shafts and drivetrain components, Fasteners and Spring materials. Whether your product is included in the scope is determined by examining its technical specifications and intended use.
Under what conditions is Torsion Test done?
The determining parameters are: Rotation speed — Constant angular speed per the standard, Gauge length — Free length defined in the standard according to specimen diameter and Temperature — Room temperature, or per the specification. 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 Torsion Test?
The specimen must be regular and undamaged, Free length is set according to the standard and Generally three specimens per set. The number of samples is determined according to the product standard and the scope to be reported.
How long does Torsion Test take?
Testing per specimen is short; a set is completed within half a working day. 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 Torsion Test result called "appropriate"?
The acceptance criterion is defined in the specification as a minimum torque, minimum number of rotations, or minimum shear strength.