Professor Christensen's research is concerned with the mechanics of materials. The behavior of polymers and polymeric fiber composites are areas of specialization. Of particular interest is the field of micro-mechanics which focuses upon materials' functionality at intermediate length scales between atomic and the usual macro scale. Applicable techniques involve the methods of homogenization for all types of composite materials. The intended outcomes of his research are useful means of characterizing the yielding, damage accumulation and failure behavior of modern materials. He is a member of the National Academy of Engineering, Fellow and Honorary Member of the American Society of Mechanical Engineers, and Fellow of the Society of Engineering Science. He also is a member of the American Institute of Aeronautics and Astronautics and the Materials Research Society.He received Timoshenko Medal in 2013.