Using this method a soap bubble is stretched out between several strings representing the edges of the object under study, and the coloration of the film shows the patterns of stress.
Griffith is more famous for a theoretical study on the nature of stress and failure due to crack propagation in brittle materials such as glass.
This was because any void in a solid, or scratch on the surface, concentrates stress, a fact already well known to machinists at the time.
From this work Griffith formulated his own theory of brittle fracture, using elastic strain energy concepts.
His theory described the behaviour of crack propagation of an elliptical nature by considering the energy involved.
[3] This relation was used to establish Griffith's criterion, which states that when a crack is able to propagate enough to fracture a material, that the gain in the surface energy is equal to the loss of strain energy, and is considered to be the primary equation to describe brittle fracture.
After pointing out an error in Whittle's calculations, he stated that the large frontal size of the compressor would make it impractical for aircraft use, and that the exhaust itself would provide little thrust.
Griffith went on to become the principal scientific officer in charge of the new Air Ministry Laboratory in South Kensington.
It was here that he invented the contraflow gas turbine, which used compressor/turbine discs alternately rotating in opposite directions.
The F.2 was ready for flight tests in 1943 with a thrust of 2,150 lbf, and flew as replacement engines on a Gloster Meteor, the F.2/40 in November.
Griffith joined Rolls-Royce in 1939, working there until 1960, when he retired from his post as the company's Chief Scientist.
He also proposed various bypass schemes, some too complex mechanically but including one which used 2 compressors in series, the arrangement subsequently used in the Conway.
Griffith carried out pioneering studies into vertical take-off and landing (VTOL) technology, such as controlling in the hover using air jets.
He proposed using batteries of small, simple, lightweight turbojets for lifting the aircraft in a horizontal attitude, a 'flat-riser'.