Obituary of Dr. Ing. Walter Schütz

Walter Schütz was born on 15 June 1929 in Nürnberg. He passed away on 1 October 2009 after a long period of illness. Walter started his career on fatigue research in 1957 in the Laboratorium für Betriebsfestigkeit (LBF) in Darmstadt where Gassner was already wellknown for the introduction of program fatigue tests to replace simple constant-amplitude fatigue tests. A milestone in the LBF period was the doctor thesis of Walter entitled: “On the relation between fatigue life obtained under constant-amplitude loading and variableamplitude loading, and the significance for designing aircraft components” (written in German
in 1965). Walter continued his research in 1969 in the laboratories of IABG ( Industrieanlagen Betriebsgesellschaft) in Ottobrunn until his retirement in 1994. In Ottobrunn he composed a new department on fatigue strength and fracture mechanics which became well recognized for research on practical fatigue problems. Also after his retirement he was still present at many national and international meetings. And he continued to publish papers.

The variety of fatigue problems “tackled” by Walter Schütz is large and as a result the number of his publications is also large. Many papers were published in various journals and proceedings of international symposia of different organizations, e.g. ICAF, AGARD, ASTM, DVM). Some noteworthy publications are listed below [1-9]. Walter was always considering the basic understanding of fatigue in view of the significance for practical applications in the industry and the behaviour of structures in service. Since he had a sharp mind he often had his doubts about the possibility to predict fatigue properties. Actually he understood that a high accuracy of fatigue predictions is an illusory target. But at the same time he was aware of much to be learned from laboratory research to improve fatigue properties and how to design against fatigue. As an example he investigated improvements of fatigue properties by surface treatments, and on the other hand possibilities of adverse corrosion effects on the material surfaces. Two other contributions written in German as LBF documents are mentioned below.
In reference [8] Walter analyzed the effect of the mean stress on the fatigue limit of different materials as shown by many experimental data. In an other LBF report [9] Walter made observations on the fatigue properties of riveted joints. Due to unexpectedly high endurances he made observations on the deformation of the driven rivet head which told him that the riveting squeeze force had a large effect on the fatigue life. A unique observation at that time
(1963).

Because Walter realized that fatigue of full-scale structures requires experimental verifications he paid much attention to realistic service load histories with random load sequences. He started and contributed to several standardized service load histories to be applied for fatigue research instead of constant-amplitude tests, and also instead of program fatigue tests. Names of these standardized service load histories are Falstaff, Helix-Felix, Wash, Wawesta and Carlos for different types of dynamically loaded structures. All people who have met Walter Schütz in person, or in technical discussions, or in social
contacts, all were readily aware of his characteristic way of participating in brainstorming conversations. He was talking only when he had been meditating about the problem. But then eagerness to contribute, dedication to arrive at the essences of problems, integrity of comments, they were characteristic for him. In Walter’s perception fundamental understanding of fatigue problems and fatigue experiments are essential for solving practical fatigue problems. He was also keen in recognizing historical developments of the knowledge about fatigue of structures and materials, and also on the various misconceptions which turned
up from time to time. He did not hesitate to pinpoint wrong ideas, but in full honesty. History and philosophy were part of his life. Walter was a good and reliable guide. We will keep his support and dedication in mind.

Couresy of Jaap Schije, Delft University of Technology, Faculty of Aerospace Engineering