Forensic Engineering Investigation Research Articles

Forensic Engineering Investigation of a Machine Guarding-Related Injury

OSHA regulations and industry-accepted standards are intended to be used in conjunction to help prevent worker injury. Despite the aforementioned intention, a point of operation injury occurred to an employee while he was operating a hydraulic rotary bending machine. The machine had been retrofitted with a two-hand control device that was intended to act as a means of point of operation safeguarding. A forensic engineering analysis of both the electromechanical design and programmable logic code — combined with a performance and prescriptive requirement analysis — ultimately revealed flaws in the design of the electromechanical system and software design. It also demonstrated a lack of adherence to the applicable industry-accepted standards related to machine guarding. These factors led to the point of operation injury.

FE Investigation of Design and Quality Control-Related Issues Contributing to Metal-On-Metal Hip Implant Failures

High levels of cobalt and chromium ions were detected in the bodies of multiple recipients of modular cobalt chrome molybdenum metal-on-metal hip implants, necessitating the revision of their implants. A forensic engineering investigation of provided discovery documents and existing literature regarding the design, manufacturing, and clinical testing of these modular hip implants was performed. The investigation revealed that the modular interfaces of the implant allowed for micromotion to induce mechanically assisted crevice corrosion at these surfaces. The debris from this corrosion resulted in the release of metal ions into the bodies of the users, forming pseudotumors and compromising the user’s health and wellbeing. The effect of this corrosion was enhanced by the galvanic couple that existed between the modular components of the implant. In addition, scanning electron microscopy (SEM) and electron dispersive spectroscopy (EDS) analysis identified silicon carbide (SiC) and aluminum oxide (AL2O3 ) particles left behind from polishing, which were embedded in the ball and liners. These particles accelerated the wear of the hip implant and further exacerbated the release of metal ions. The designers of future hip implants should take care in preventing the occurrence of the above-stated factors.

Forensic Engineering: The Investigation of The Causes of Asymmetry Trailing Edge Flap During The Aircraft Boeing 737 Landing.

Forensic engineering is the application of engineering principles and methodology to answer questions of fact. These questions of fact are usually associated with accidents, crimes, catastrophic events, property degradation, and various types of failures. This research discusses a serious incident that occurred on a Boeing 737-300F aircraft operated by The XYZ airline which operates unscheduled domestic flights in Indonesia, with a flight route from Jakarta Soekarno International Airport (CGK) to Samsoedin Noor International Airport Banjarmasin (BDJ). When the plane was about to land, and the pilot operated the flaps from the 30o position to the 40o position, there was an asymmetry between the left and right flap trailing edges of more than 20o, which caused the plane to become unstable because it rolled to the left, and the pilot was unable to control the plane when landing, which causing a serious incident on the plane. This research aims to find the root cause of trailing edge flap asymmetry of more than 20o as an evaluation for companies in determining and implementing corrective and preventive actions so that this problem does not happen again in the future. This research will use forensic engineering investigation methods and carry out chemical composition testing (Optical Emission Spectroscopy); metallographic testing (micro and macro structure observations); FESEM testing and microchemical composition testing (EDS); and hardness testing. Then for each test result an analysis is carried out based on scientific knowledge. The results of the investigative analysis were to find the root cause of the trailing edge flap asymmetry problem of more than 20o. After getting the root cause of each method, the author then compares the results of one method with another method to draw conclusions to consider and determine corrective and preventive actions to be taken and implemented in the company or organization.

Forensic Engineering Investigation of Factors Contributing to the Explosion of an International Natural Gas Pipeline

Following the explosion of a natural gas pipeline that resulted in extensive property damage, personal injury, and loss of life, a forensic engineering investigation was performed to determine factors that signifi-cantly contributed to the failure. Metallurgical analysis of the failure region resulted in the conclusion that the pipeline rupture was caused by hydrogen embrittlement acting on hard spots created during manufactur-ing. The next phase of this investigation involved root cause analysis of factors contributing to the pipeline rupture as well as evaluation of missed risk-reduction opportunities of the nondestructive analyses employed. It was ultimately determined that hydrogen embrittlement, caused by improper operation and maintenance procedures, resulted in an overabundance of hydrogen from excessive cathodic protection. Additionally, excessive operating pressure exceeded the resulting degraded ultimate capacity of the pipeline, which then manifested in the rupture of the natural gas pipeline and the ensuing explosion. It is recommended that op-erators exercise due diligence by considering the age of a pipeline when determining appropriate operating, monitoring, and maintenance procedures.

Forensic Engineering Investigation of Electrical and Electronic Causes of an Industrial Equipment Failure

This case involved industrial equipment whose repeated, seemingly random failures resulted in the buyer of that equipment suing the seller. The failures had been isolated to a group of several transistors within electro-mechanical modules within the equipment, but the root cause of those transistors failing had not been determined. The equipment seller had more than 1,000 units in the field with no similar failures. And the electro-mechanical module manufacturer had more than 20,000 units in the field with no similar failures. Electrical contractors hired by the buyer had measured power quality, and reported no faults found in the three-phase power at the equipment terminals. This paper presents circuit analyses of the failing electro-mechanical module, basics of electrostatic discharge damage and protection, and the root cause of these failures — an electrical code-violating extraneous neutral-to-ground bond in a secondary power cabinet.

Computer Fire Modeling and the Law: Application to Forensic Fire Engineering Investigations

Computer fire modeling can be a two-edged tool in forensic fire engineering investigations. Professional standards of care recommend that fire modeling’s primary use is in examining multiple hypotheses for a fire as opposed to determining its origin. This paper covers the current acceptable benefits of computer fire models, historical and pending legal case law, and methods to use modeling results within expert reports and testimony. Particular issues reviewed are the use of animations versus simulations, evidentiary guidelines, and authentication using verification and validation studies.

Lessons Learned from a Forensic Engineering Investigation of a Scaffold Support Failure

During use, a scaffold support allegedly failed, causing injuries to the user when he fell. The plaintiff’s expert identified a defective weld as the cause of failure and opined that the product was improperly designed. This paper examines methods used to evaluate the circumstances of and claims made regarding the incident. A combination of engineering methodologies, including metallurgical evaluation, stress analysis, and physical testing, was used to examine the plaintiff’s claims of deficiencies in the design and fabrication of the product. The engineering methodologies refute claims made about the structural capacity of the product by the plaintiff’s expert and the fundamental cause of failure. This paper examines themes related to the presence of apparent defects/failure and the necessity of verifying postulated hypotheses. It also examines the efficacy of analysis and testing as part of implementation of the “forensic engineering method” in verifying or rejecting hypotheses en route to offering expert opinions in forensic engineering investigations.

Computational Fluid Dynamics Modeling of a Commercial Diving Incident

A commercial diver using surface-supplied air was “jetting” a trench, which was using high-pressure water via an industrial “jetting hose” connected to a pressure-compensated tool to cut trenches in silty sea bottoms. This tool used high-pressure water pumped from the tender boat down to the diver. It was reported that man-made objects in the area cut the jetting hose, resulting in uncontrolled diver movement and subsequent injury. There were no direct witnesses available. The subsequent forensic engineering investigation used traditional calculations, laboratory testing, ergonomics, biomechanics, and computational fluid dynamics (CFDs) to determine the limits of the physics involved in order to assess the feasibility of the reported scenario. Specifically, CFD modeled the mass flow exiting the tool’s two ends and the cut in the hose as well as modeled the diver’s flow resistance while propelled through the water. The results indicated the applicable physics precluded the events as described.

Imprecise abstract argumentation as a support for forensic engineering

PurposeCivil engineering structures are regularly confronted with failures that can lead to catastrophic consequences. It is important, after a failure, to be able to identify the origin and the sequence of factors that led to it. This failure analysis by experts, called forensic engineering investigation, generally leads to the drafting of an expert report. These reports do not inform on the processes that guided the experts to a conclusion and the uncertainties involved. This paper aims to propose a new methodological approach to formalize the opinions of experts in forensic engineering.Design/methodology/approachThe research consists in combining abstract argumentation with the theory of imprecise probabilities to take into account epistemic and stochastic uncertainties to support forensic engineering investigation.FindingsA model and a tool to support forensic analysis are presented. An application on the collapse of the Brumadinho dam highlights the interest of the chosen approach.Originality/valueThis work is the first use of the abstract argument framework in civil engineering, and so in forensic engineering. Furthermore, it provides an innovative model based on imprecise probability for AAF.

Forensic Engineering Investigation on a Collapsed School Building Involved Multiple Deaths: A Real Case Report

Forensic Engineering Investigation on a Collapsed School Building Involved Multiple Deaths: A Real Case Report

Forensic Engineering Investigation of a Pipe Joint Tester Explosion

A construction laborer was killed while operating a pipe joint tester, which was used to test joints between sections of newly installed sewer pipe. The joint tester contained a donut-shaped rubber bladder, which was inflated with compressed air to seal against the inside of the pipe joint during the test. During a pipe joint test, the pipe joint tester bladder exploded without warning. The joint tester operator was fatally injured when he was struck by pipe joint tester components and the air blast. A forensic engineering investigation was conducted to determine the role of the design and construction of the pipe joint tester in the cause of the incident.

Forensic Engineering Investigation of the Catastrophic Breakdown of a Diesel Engine in an Emergency Generator Set

A large-displacement 16-cylinder diesel engine was coupled with a 1750 kW-rated generator set to provide emergency power to an international airport parking facility. It had been in service for seven years, and had accumulated only 242 operating hours from a regular monthly test procedure. On the day of the incident, less than three minutes after starting up, the engine began smoking, running roughly, and then failed catastrophically. A forensic engineering investigation was undertaken to determine the cause. Two cylinders in opposite banks had been damaged. The proverbial “smoking gun” was found — an obstruction comprising a rubber gasket within the main oil gallery leading to these cylinders. The investigation explored the probable method and means that this gasket was entrained into the gallery. The results of the analysis attempted to provide for an assessment of relative liability of the parties.

Forensic Engineering Analysis of Projectile Thrown from Phantom Vehicle

This paper presents a case study involving an 8-lb “projectile” piece of concrete thrown from a phantom vehicle into the windshield of a semi-tractor truck, subsequently striking the driver’s (plaintiff’s) head. A witness told the investigating officer that the phantom vehicle was a white-rear dump truck similar to the trucks he’d seen coming in and out of a construction entrance at a nearby park. However, no follow-up investigation was conducted by investigative officers. The lead author was retained by the plaintiff’s attorney to follow up and investigate the witness’ observation of the phantom white-rear dump truck in an attempt to identify the probable source of the concrete projectile, locate the phantom vehicle, reconstruct the incident, and determine the probable cause of the incident. Several forensic engineering techniques were used during the forensic engineering investigation, including evidence analysis, photography, high-definition scanning, photogrammetry, evaluation of the accident timeline, physical testing, case study analysis, projectile analysis, and application of the process of elimination methodology. Through the forensic engineering analysis, the probable source of the projectile concrete was identified, the white-rear dump truck and driver were identified, the accident was reconstructed, and the probable cause of the accident was determined.

Forensic engineering expert training within the system of higher and supplementary vocational education: problematic aspects

Introduction. Forensic structural engineering dates back to the late 20th century. Since then its theoretical and methodological fundamentals have been developed, and considerable practical experience has been accumulated. Nowadays, it is one of the most in-demand type of expert investigations performed in the course of judicial proceedings in Russia; therefore, it has boosted a significant inflow of specialists into forensic investigation organizations. At present, their total staffing exceeds ten thousand specialists. However, the professional training of forensic engineering experts is often heavily and rightly criticized by investigators, judges, and parties to judicial proceedings, defending their legitimate interests. The ever growing number of forensic expert investigations, ordered by the courts, and the growing complexity of tasks to be tackled by experts, have pre-determined the need for an effective expert training system, so that the qualification of experts could meet the rising demands of present-day court proceedings. The objective of this study is to develop the basic principles of this system. Materials and methods. This article is based on the assumption that the special features of activities, performed by forensic experts, determine, to a great extent, the essential principles of effective teaching of this discipline, as well as the major problems arising in the course of student training. The authors describe a combination of didactic methods (oral, printed and verbal, illustrative methods, etc.), teaching techniques and tools used to address these problems. Results. A coherent overview of features of a forensic structural engineering investigation (FSEI), including the procedural nature of its performance, the predominantly regulatory character of forensic investigations, as well as the practical value of FSEI findings substantially improve the efficiency of training highly qualified specialists. The statistics indicate that over 99 % of students can successfully complete training programs. Conclusions. A comprehensive, substantive procedural approach to the explanation of educational materials has proven to be effective. This approach is tailored to the specific nature of forensic activities, and it should be fully integrated into the process of training forensic engineering experts.

Forensic Engineering Investigation into Factors Contributing to Explosion of a Consumer-Grade Tabletop Torch

In early 2013, approximately 3,500 consumer-grade tabletop torches, designed for use with citronella oil to ward off insects, were sold by a retailer. Within six months of their debut, 22 of these products experi-enced sudden explosions, resulting in one fatality and 21 severe burn injuries to consumers. The author was retained as an expert in the fatal explosion case to determine the root cause(s) that led to these explosions. This paper will describe the detailed, experimental-based investigation that was carried out to reveal design, manufacturing, and marketing defects for which the designer of the torch, the manufacturer of the fuel, and the retailer of the final product were responsible. It was determined that the explosions occurred as a result of a “perfect storm” scenario that involved defective product design, defective marketing of the product through the sale of incompatible fuel by the retailer, and deficient warning instructions by the manufacturer.

Forensic Engineering Investigation of a Furnace Oil Supply Line Fitting Leak

A basement oil leak was reported to a service company, which immediately replaced a supply line SAE 37° fitting body while leaving the flared copper lines in place. An environmental remediation claim was later made against this service company, alleging improper installation of new supply lines within the prior year. Fuel delivery records and heating degree day records were analyzed, revealing a consumption rate discrep-ancy versus the homeowner’s narrative. An experimental apparatus was designed to evaluate leak rates for flared fittings in tightened and partially loosened states. The modeled expected consumption rate results inferred tampering with the fittings several days prior to the leak report. The experimental technique and consumption rate analysis withstood a Daubert challenge for relevance at the mediation conference.

Improving reliability in forensic engineering: the Delft approach

Based on established theories from literature and best practices of forensic investigations in aerospace engineering, civil engineering and biomechanical engineering, the Delft University of Technology has developed a Delft approach for forensic investigations. This integrated approach consists of three elements. First, because a product has a life cycle with various phases, it is of importance to consider these phases when a failure is investigated. Second, it is acknowledged that failure is a multifaceted phenomenon. Therefore, the ‘Tree House of Failures’ was developed, a taxonomy or categorisation of failure causes, which addresses main groups of causes of failure related to product, instruction and execution. Third, use of a standard investigative approach with the steps ‘orientation’, ‘data collection’, ‘hypotheses generation’, ‘hypotheses testing’, ‘recommendations’ and ‘findings reporting’ is advised. In the Delft approach, the ‘ring of trustworthiness’ is used to underline the mind-set that a forensic engineering investigator should have to assure the investigation’s reliability and validity. The ring of trustworthiness states that an investigation should be objective, repeatable, verifiable, complete and correct. This paper presents the Delft approach for forensic investigations and explains how to use it to prevent several common pitfalls and biases that occur in various stages of a forensic engineering investigation. This approach aims to increase the reliability of forensic engineering investigations worldwide.

FORENSIC ISSUES OF CATEGORIZING CONSTRUCTION PROJECTS AS PERMANENT STRUCTURES: METHODOLOGICAL GUIDELINES FOR FORENSIC EXAMINERS

The article addresses the issue of subsuming construction projects under the category of permanent (non-permanent) structures. The authors offer detailed criteria for successful resolution of this issue, and present the appropriate course of inquiry for this line of forensic engineering investigation. Special emphasis is placed on the resolution of complex forensic situations. The paper incorporates a systematic overview of primary and secondary indicators for identifying buildings, structures and facilities as permanent or non-permanent. Recommendations draw on extensive regulatory resources, as well as generalization, systematization and analysis of current forensic practices, and are illustrated with specific examples.

Forensic Engineering Investigations of Residential Clothes Dryer Fires

Residential clothes dryers are common in the United States, and thousands of residential fires involving clothes dryers occur each year. Forensic engineers are called upon to conduct scientific analyses of the causative factors in these fires. Forensic engineering investigations of clothes dryer fires consider design, installation, use, and maintenance of clothes dryers as well as evaluate ignition sources, first fuel ignited, fire containment and fire spread. A forensic engineering methodology for investigation of clothes dryers will bepresented in this paper, drawing on experience from hundreds of residential clothes dryer fire investigations.

Forensic Engineering Investigation of a Fatal Farm Tractor Incident

A farm owner was found unresponsive with crushing head injuries on his property in rural Ontario. His small farm tractor was found 60 meters away down a small incline with the engine running and transmission in neutral. The owner’s son alleged that when the parking brake was engaged (with the engine running and transmission in neutral), this tractor’s parking brake would “pop out,” allowing the tractor to move. Field tests were conducted on the tractor to attempt to duplicate the scenario and to determine if the alleged sequence of events was plausible. Components of the parking brake and one exemplar were assessed with specialized metrology to determine whether they were within the manufacturing specifications on the blueprint. A 3-D CAD model of fit was created, and several variances were identified between the parts and the factory drawing. The results of the analysis concurred with the scenario that these variances led to the disengagement of the parking brake and operator fatality.