Mechanical testing laboratory

The mechanical testing laboratory offers a wide range of equipment for studying the mechanical behaviour of components and material samples, using destructive and non-destructive methods.

The laboratory allows examination of the conditions and parameters that affect material strength and durability due to stress, fatigue, fracture and corrosion. It is important that materials are tested to determine how they behave throughout their lifecycle. The laboratory contains state-of-the-art modern testing equipment, and is used for education and industry-led research.

The loading of specimens and components is possible under uniaxial tension, compression, and bending, for both static and fatigue testing.

A range of inspection, non-destructive testing equipment and structural health monitoring systems are used for crack and stress measurement.

Key facts

Fully-equipped workshop and lab technicians for industry led research, teaching and project support.
A range of static test machines and accessories for tensile, compression, bending, fracture toughness, DCB, and more testing.
A range of servo-hydraulic materials and fatigue testing facilities.
Strain gauges: which link to P3 strain indicator and recording system, which can be linked to a computer for analysis.
Fully automated software's for performing KIC and JIC fracture toughness testing and analysis according to standard test methods.
Compliance measurements in fracture mechanics tests using calibrated clip gauges.

Key equipment

Static testing machines – these can be configured for industrial bespoke research requirements, all Instron controllers. We have a range of machines and load cells which have the following load cells and are able to test a range of specimens types and sizes:

100kN
30kN
5kN
2kN

Servo hydraulic fatigue testing machines – these can be configured for industrial bespoke research requirements, all using Instron controllers. Many of these machines are capable of carrying out both fatigue and static testing:

1 x 500kN - a versatile general purpose test machine with top mounted actuator and load cell; Note: the hydraulic grips are rated to 250kN.
1 x 250kN - a versatile general purpose test machine with bottom mounted actuator and top mounted load cell.
2 x 100kN - used for testing small standard samples (e.g. compact tension test specimens).
1 x 25kN - our most modern machine, used to test both static and fatigue specimens using sophisticated software which is linked to a video extensometer for accurate strain and displacement measurements.

Environmental chamber – this is used to test the effects of specified environmental conditions on materials, specifically fracture toughness. Operating temperatures range from -70°C to +400ºC.

Drop tower – for low velocity impact testing.

Corrosion testing – we can simulate sea conditions, e.g. temperature and salt content, to test for corrosion and crack propagation.

Hopkinson Bar facility – the tri-function Hopkinson Bar is able to test material specimens in compression, tension, torsion and combined loadings. It achieves strain rates of up to 5000/sec in tension and 10000/sec in compression. The bar can be configured as a direct impact bar for measuring low impedance foams and similar materials. The bar is supported with finite element (FE) modelling to develop novel.

Strain and displacement measurement – the methods used are:

Strain gauging - used to measure applied or residual stress (through centre hole drilling).
Digital image correlation (DIC) measurements.
Video extensometer.
Laser extensometer.
Standard extensometer.
Linear variable differential transformer (LVDT).
Crack opening displacement (COD).

Mechanical testing laboratory staff

Summary of applications

Cranfield staff work on a range of research applications, with a number of industrial and academic partners, to gather test data using mechanical testing equipment.

Some of our areas of expertise and research include:

Fatigue and fracture mechanics analysis – methods of assessment to test fitness-for-purpose, damage tolerance and evaluation of repair strategies.
Welding and additive manufacturing.
Structural reliability analysis – providing design optimisation by systematic quantification of uncertainties and calibrating design standards.
Space and Aerospace materials and applications.
Automotive and motorsport applications.
Design of structures and components – design, analysis and performance assessment of structures and structural details; testing and characterisation of new materials; engineering for installation, manufacturing and large-scale production.
Composite materials – determine the properties of new materials to optimise design and manufacturing.
Corrosion analysis – with a focus on modern materials such as very thick plates where combined effect of fatigue and corrosion assessment is required.
Renewable energy and marine structures.
Requalification of structures – extending the service life of installations by improving structural integrity.