Forensic materials engineering, a branch of forensic engineering, focuses on the material evidence from crime or accident scenes, seeking defects in those materials which might explain why an accident occurred, or the source of a specific material to identify a criminal.

Many analytical methods used for material identification may be used in investigations, the exact set being determined by the nature of the material in question, be it metal, glass, ceramic, polymer or composite. An important aspect is the analysis of trace evidence such as skid marks on exposed surfaces, where contact between dissimilar materials leaves material traces of one left on the other.

Provided the traces can be analysed successfully, then an accident or crime can often be reconstructed. Another aim will be to determine the cause of a broken component using the technique of fractography.

Forensic materials engineers are often involved in product failures (e.g., a critical component of a safety device), process failures (e.g., a manufacturing does not produce materials with acceptable properties for an application), and design failures (e.g., many products prematurely fail).

Many different types of defects, which are often investigated and characterized through the process of Failure Analysis, may be involved in the crime or accident to cause some sort of failure. For example, there are primary and secondary defects that may occur in products designed for consumer use.

Defects may exist prior to use: a primary defect, or defects may develop during use. Moreover, primary defects may also turn into secondary defects over time. Forensic materials engineers are involved in examining the scenario and identifying relevant defects and their probability in being causal factors in the crime or accident.

A crucial aspect of forensic materials engineering is to avoid defining causes of failure in too binary a manner (i.e., narrowly framing the problem through questioning whether a particular component involved in the crime or accident was either defective or abused by the user). Ascertaining cause inevitably leads to identifying as many possible factors that could contribute to a failure through the generation of fault tree diagrams (see diagram at right). Following the generation of the possible causes, investigations are planned and evidence is collected to then determine which of the possible factors is/are probable in having caused the failure. Within probable causes, there are root causes which may consist of multiple factors: physical, human, and latent causes or factors.

During the litigation process each party involved, will on occasion, retain an expert forensic materials engineering witness to perform a failure analysis and compile a report. During such investigations, the parties are often present in the same location for the review of the physical evidence, and can be present for materials analyses. However, each party will often then independently perform their own observations of collected images and data and subsequently execute interpretations and analyses in preparation for depositions and/or court proceedings.