Technical Tips

Sharing knowledge gained from investigating the fundamental causes of failure.

Beware of the insidious effects of localised corrosion damage in crevices and below gaskets


Crevice corrosion can have highly detrimental consequences due to the localised nature of attack that often goes undetected in-service until final failure, associated with leakage or localised stress concentrations, occurs.

Read more

Orientation effects in creep


Creep in materials refers to the gradual strain extension of that material under sustained load over extended time periods. In metals, creep is of particular concern because it typically only manifests over long time periods, for example ten to twenty years, and at temperatures which are in excess of approximately 40% of the melting point. However at higher temperatures or high stress levels the period in which damage manifests can reduce significantly.

Read more

Orientation effects in metals can result in unexpected consequences.


Although it is normally assumed that engineering materials are isotropic this assumption is often not valid.

Read more

Remember corrosion exacerbates the potential for fatigue failure


Fatigue of engineering materials and their degradation through micro-cracking, as a result of cyclic loading, is extremely common in materials, especially metals and alloys, accounting for up to eighty percent of all structural failures. Real world engineering structures are subjected to a range of environmental conditions, which can and usually do exacerbate the fatigue circumstances and accelerate the fatigue crack advancement process.

Read more

The pros and cons of galvanic coupling

JULY 2017

Cathodic protection is a method of reducing the rate of corrosion damage to a metal surface by supplying it with electrons from an external source, effectively forcing it to become the cathodic (passive) element of a galvanic cell.

Read more

Don't discount small critters and biological growths.

JUNE 2017

Microbial Induced Corrosion can cause rapid localised attack and degradation of many metals including stainless steels.

Read more

Beware of highly stressed components working in a corrosive environment

MAY 2017

The combined influences of tensile stress and a corrosive environment can lead to catastrophic failure of susceptible materials by stress corrosion cracking mechanisms (SCC). Often these failures occur after relatively short periods in operation without warning, but with proper understanding and care, SCC can be avoided.

Read more

Don’t preclude DIC

APRIL 2017

Digital Image Correlation (DIC) is a non-contact optical technique for the analysis of surface displacement fields of a specimen during deformation/loading. This information can be used for subsequent analysis of the surface strain and has the potential to allow for continual in-service monitoring of components.

Read more

Value your tyres

MARCH 2017

Accurate modelling of material properties is vital in numerical analyses where changes in material properties can have a significant effect on the results of numerical analyses such as those employed in the modelling of automotive tyres.

Read more

Temperature effects on mechanical property performance.


In today’s ever more stringent economic climate, reliable material performance is becoming even more important, as premature failures are not readily tolerated, especially when they can be anticipated and avoided. Sometimes such failures are related to the temperature behaviour of materials, and this month’s Technical Tip refers to two examples that illustrate such temperature related failures.

Read more

Overlook stress concentrations at your peril


The effect of stress concentrating features such as notches, fillets, grooves and threads, has been known for many years and has been documented in many texts. However they are often overlooked and cause failure by locally increasing stresses and aiding fatigue crack imitation.

Read more

Preserve your fracture surfaces or lose information


When a component fractures, the atomically clean fracture surfaces contain many features indicative of how and why the fracture occurred. Preservation of these fracture surfaces is one of the most important aspects of any failure investigation and precautions should be taken to provide the failure analyst with a sample in the best possible condition for accurate assessment of the failure scenario.

Read more