and served as its Principal Engineer since 1987 and vice president since 1996. Johnston has co-authored a book titled "Structural Dynamics by Finite Elements" published by Prentice-Hall in 1987. On May 31, 2018, Johnston stepped down from the position of chief executive officer to be an executive chairman. Catherine Corrigan was named president of Exponent, Inc. on July 29, 2016. Dr. Corrigan joined Exponent's Philadelphia office in 1996, was promoted to principal in 2002 and to corporate vice president in 2005. Corrigan was promoted to group vice president to lead the Transportation Group and joined the company's operating committee in 2012. On May 31, 2018, Corrigan was appointed to chief executive officer. Incorporation Failure Analysis Associates was founded as a partnership, incorporated in 1968 in California and reincorporated in Delaware as Failure Analysis Associates, Inc. in 1988. In 1989, McCarthy reincorporated Failure Analysis Associates, Inc. in Delaware under a holding company, The Failure Group, Inc. and took The Failure Group, Inc. public in 1990. The company changed its name to Exponent, Inc. in 1998. Company activities Exponent has been involved in the investigations of many well known incidents including the now debunked report aired on Dateline in 1993 about fires and explosions involving sidesaddle fuel tanks on Chevrolet C/K trucks, the disputed Consumer Reports finding on Suzuki roll-over safety, the 2009–2010 Toyota vehicle recalls, the crash of American Airlines Flight 587 among many other aviation accidents, and the Exxon Valdez oil spill. The Federal Emergency Management Agency also hired Exponent to examine the Oklahoma City bombing damage aftermath, specifically the damage to the Alfred P. Murrah Federal Building. NASA hired Exponent in 1986 to determine the causes of the Space Shuttle Challenger disaster. In 2003, Exponent was hired by the U.S. government to investigate the Space Shuttle Columbia disaster. In 2017, Samsung hired Exponent to determine cause of thermal runaway of the Note 7 Phone batteries. Exponent has ISO 9001 accreditation, indicating independently audited and certified quality management practices. The company also is certified for battery, energy storage and compliance testing. Neutrality The quality and neutrality of reports produced by the company have been called into question on various controversial topics. Common points of critique include corporate denialism and that, for industrial clients, only favorable reports are seemingly produced. Examples include Exponent arguing that dioxins and PFAS do not cause cancer. These questions of conflict of interest have been disputed.