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Fracture and Mechanical Testing Laboratory

Fracture and Mechanical Testing
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The Fracture and Mechanical Testing Laboratory is used for fracture toughness, tensile and large-scale and pressure testing, all at a range of strain rates and test temperatures. It is also used for all mechanical testing in a seawater environment.

TWI’s Standard fracture toughness testing capabilities features:

  • UKAS accredited for carrying out fracture toughness tests to ASTM E1820, BS 7448-1, BS 7448-4,  BS EN ISO 15653, ISO 12135
  • Experience of testing to ASTM E1921 and BS 8571
  • Thermal chamber for testing at -160 to +200°C
  • Local heating & cooling for testing from -196 to +400°C
  • Test CT, SENB and SENT specimens
  • Specimen sizes from 5x10mm up to 150x150mm (depending on strength/tensile properties)
  • 16 universal testing machines covering a range of capacities up to 1750kN
  • Provision of UKAS accredited tensile testing and Charpy testing as well
  • Representation on British and International standards committees to influence and communicate ongoing changes to IS0 12135, BS 8571 and BS EN ISO 15653


  • Generation of fracture toughness data in terms of J, CTOD and K
  • Fracture toughness data as single point values or tearing resistance curves
  • Data suitable for fitness-for-service assessment

Testing large scale test specimens, or full structural components to demonstrate their fracture performance under load, in a way that matches the in-service component behaviour. Since the 1960s TWI has been designing and building rigs to test large and complex components.

  • Wide plate test rigs of 4000 tonnes and 3500 tonnes
  • Pipe tension test rig of 1000 tonnes capacity
  • Pipe bend test rigs of 6MN capacity and 30MN
  • Pressure test pit with capacity of 3.7m x 13.5m x 3.5m deep, with side anchors of 500kN, end anchors of 15,000kN and 2000 bar internal pressure
  • Crack arrest test panels and notched wide plate test panels
  • Design of large scale bespoke testing equipment for specialised applications
  • Typical applications include pipeline girth welds, offshore mooring chains, forgings and castings, ship hull structures

Benefits: Structurally relevant mechanical properties for validation or design.

TWI’s bespoke fracture testing capabilities include:

Environmental fracture testing facilities to test in seawater or sour service environment

Specialist equipment allows high strain rate testing up to 20m/s test velocity

Digital image correlation capability for strain mapping

Testing of thinner sheet materials using centre cracked tension specimens.

Instrumented Charpy tests and analysis

Creep testing at temperatures up to 1200°C

Pellini (drop weight) testing

Interpretation of fracture toughness results, such as pop-ins, invalidities, metallography, audits

Bespoke fracture testing and test rig design

Fracture mechanics assessment such as ECA and FFS assessment (including software)


Benefits; a range of options to support research work or unusual testing requirements alongside standard or large-scale testing.

The key industry benefits from this laboratory are the generation of characterisation, comparison and/or proof data for materials in terms of fracture toughness, strength, static and cyclic behaviour in seawater, pressure performance and creep properties.  The results of these tests are mainly used for material validation and integrity assessment. TWI is uniquely placed to offer a wide range of laboratory services, along with expertise, research and Standards involvement to best provide technical advice and interpretation alongside the data.

Equipment factsheets

750 joule Charpy impact testing machine

High-rate servo-hydraulic test machine

See here for a full list of TWI equipment.

Fracture Toughness Testing at TWI

To assist with creating fracture toughness testing requirements you can quickly send details and specifications using our enquiry form:

Fracture Toughness Testing enquiry

For more information please email: