Forensic engineering can be defined as a kind of investigation of failures that can be normal as well as catastrophic which will lead to certain legal scrutiny.
Therefore, any kind of forensic engineering test will involve detailed investigation of products, materials, structures or components which either totally fail or fail to operate as it was designed, which can result in economic loss, property damage or personal injury.
The repercussion of such failure may invite action under civil or criminal law or any further litigation.
Generally, the basic purpose of such forensic engineering consulting is to locate the reasons for failure keeping in view to improve the performance of the component, or help a court in deciding the actual facts about an accident.
With time, the engineering field has much evolved over a period of time and the field of forensic engineering has also undergone many changes.
Very early examples of forensic engineering were seen during the investigation of failure of bridge e.g. the disaster of Tay rail bridge of 1879 and also in 1847 the disaster of Dee bridge.
Also, many early accidents of rail prompted various inventions of tensile testing and fractography of samples of all failed components.
In forensic engineering, it is vital to investigate and collect data about the materials, structures, products or components which has failed. This will involve collecting evidence, inspection, developing models, measurements, obtaining exemplar products as well as performing experiments.
Often number of measurements and testing are done in an Independent laboratory or some other unbiased laboratory with impeccable reputation.
All the failure analysis methods also will examine the product/process failure in very structured and systematic manner keeping in view of safety engineering.
There is certain similarity between forensic engineering and forensic science e.g. crime scene and accident analysis scene, evidence integrity and court appearances etc.
Both these disciplines may make extensive applications of optical as well as scanning electron microscopes. Also, the use of following tests is very common.
- Use of spectroscopy to examine certain critical evidence.
- Radiography by using X-rays
- Neutrons to examine thick products for certain internal defects before attempting any destructive examination.
Tracing evidences becomes an important factor for reconstructing the sequence of certain accident. As an example, if tire burn marks is noticed on road surface, it will help to determine estimated speed of the vehicle while brake was applied.
Ladder feet also leaves certain movement trace of the ladder and may show the reason of accident.
In case, a product fails where no obvious reason is found then SEM and X‑ray spectroscopy is performed to reveal if there is any presence of certain aggressive chemicals which may have left traces.
Extracting physical evidence by using digital photography is another major technique often used for reconstruction of forensic accident. Camera matching, photo rectification and photogrammetry techniques are used for creating 3-dimensional views from the 2-dimensional photos taken at any accident scene.
Forensic materials engineering will involve methods which is applied to certain specific materials, e.g. glasses, metals, ceramics, polymers and composites.