Christian was easily counted amongst the world's top researchers in computational mechanics. He has drastically influenced our community over the past 25 years with his penetrating ideas and perfectly crafted publications, whose reading always brought joy and new insights to the readers. Christian's phenomenal expertise in computational mechanics was based on his deep knowledge of mechanics and his constant reflection on the important role that mathematics plays in the general treatment of problem solution. His papers are noted for a sharp attention to mathematical structure, its exploitation for the development of theory, and its leveraging for sound computation. The bulk of his over 100 archival papers revolved around material modeling with noteworthy work in an amazing breadth of sub-topics: non-linear continuum physics, applied differential geometry and constitutive theory of materials; computational mechanics, discretization techniques, finite element design and solution algorithms; variational principles for dissipative problems in solid mechanics, including multi-physics scenarios; phenomenological material theory, elasticity, viscoelasticity, plasticity, damage and fracture mechanics; micro-mechanics of materials, phase transitions, defect theories, general configurational mechanics; homogenization techniques and scale bridging, top-down modeling of materials with microstructures; coupled multi-field problems, thermo-, electro-, magneto-, chemo-mechanical coupling; material stability analyses, relaxation techniques, bifurcation analysis; structural models, shell theories, finite elements for solid structures in multi-field environments; optimization methods, parameter identification of complex material models, and experimental mechanics.
Christian devoted an impressive intensity and infectious love for these topics that can be evidenced by the accomplishments of his many students. Christian was the personification of the perfect scholar and a beloved mentor to young scholars, a person who devoted his life and personality to advance and promote computational mechanics and material theory: A great loss for the international community.
Christian was also internationally active and well known for being the consummate host. He organized conferences and workshops and was a distinct member serving on several editorial boards and organizations. Conferences and workshops hosted by him were well attended by guests who departed with nothing but fond memories. Visitors to the Institute cherished their time there and he was always a sought-out friend at meetings around the world. Christian was a fine downhill skier, lover of sweet desserts, and special person to be around.
His early death leaves a deep void in the hearts of many, but most tragically for his wife and life partner Elke and their two sons Robert and Paul.
Sanjay Govindjee, University of California, Berkeley
Jörg Schröder, Universität Duisburg-Essen, Germany
Christian Linder, Stanford University, California