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'''Qian Weichang''' a Chinese physicist and applied mathematician (1912-2010) whose work ranged across mechanics, applied mathematics and engineering science, and who was a founder of modern mechanics in China and one of the designers of the country's earliest missile and aircraft programmes.

== Early Life and Education ==
Qian Weichang was born on 9 October 1912 in Wuxi, Jiangsu province, into a family with a scholarly tradition but modest means. He suffered from polio as a child and was left with a weakness in one leg, and he turned to study as others turned to sport, developing the extraordinary intellectual appetite that marked his whole life.

He entered Tsinghua University intending to study physics, but his marks led him into the study of the history of Chinese science, and it was only later that he returned to mathematics and physics. He graduated in 1935 and then worked as a teacher before winning a scholarship to study in Britain, funded by the Boxer Indemnity funds.

He studied at the University of London under Geoffrey Ingram Taylor, a leading figure in fluid and solid mechanics, and later in Paris with the mathematician Jacques Hadamard and the physicist Paul Langevin. He obtained a doctorate in 1942 with a dissertation on the theory of elastic plates and shells, a subject that became a lifelong concern.

== Scientific Career in Mechanics ==
Qian Weichang's work spanned the mechanics of solids and fluids, the theory of elasticity, and the application of mathematics to engineering problems. He made lasting contributions to the theory of shells and of the buckling of thin structures, and to the mechanics of turbulence and of wave motion, publishing in the leading journals of the field.

He was particularly interested in the interlacing of theory and practice, and he argued that applied mathematics must be directed toward the solution of real engineering problems rather than confined to abstract puzzles. This conviction led him into the design and analysis of aircraft structures and of power machinery.

He returned to China in 1946 and taught at Tsinghua University and then at Peking University, where he became professor of mechanics. He helped to establish the study of mechanics as a discipline in Chinese universities, and he trained a generation of students who went on to lead research in engineering and applied mathematics.

== Engineering Science and National Projects ==
Qian Weichang helped to found the Institute of Mechanics of the Chinese Academy of Sciences, and he was a leading advocate of engineering science, the idea that engineering should be founded on systematic scientific principles rather than on empirical rules alone. He used this approach in the analysis of complex structures and machines.

In the 1950s and 1960s he took part in the early planning of the Chinese missile and aircraft industries, applying his knowledge of mechanics to problems of structural strength, vibration and stability. He was among the scientists appointed to advise on the formulation of the national science and technology plans.

He was elected a member of the Chinese Academy of Sciences in 1955 and served in senior advisory posts, and he helped to shape the national programme of research in mechanics and in the related fields of aeronautics and engineering. His role was that of the scientist who connects abstract theory to the needs of industry and defence.

== Education and Writing ==
Qian Weichang was one of the great teachers of his generation. He taught at Peking University and later helped to found a school of applied mathematics there, and he wrote textbooks that were used throughout the country. He insisted that students master fundamentals before specialising and that they learn to think in terms of physical models.

He was also a prolific essayist and populariser of science. He wrote on the nature of mathematics, on the relation between science and society, and on the history of scientific thought, and his writings reached a wide audience beyond the universities. He was known for an austere and plain style and for a refusal of intellectual pretension.

He argued for the integration of science and engineering education, holding that the education of engineers must include genuine scientific training and that of scientists a practical acquaintance with machines and structures. His ideas influenced the reform of technical education in China in the decades after 1949.

== Legacy ==
Qian Weichang was honoured as a founder of modern Chinese mechanics and as one of the architects of engineering science in the country. The Shanghai University that took his name, and institutions and prizes associated with him, continue to promote the approach to applied mathematics and mechanics that he championed.

He lived to the age of ninety-seven, dying on 30 July 2010, and remained active in writing and teaching into his last years. He was the last surviving member of the group of scientists who had studied abroad and returned to build the scientific institutions of the People's Republic.

His legacy lies in the discipline he founded, the students he taught, the textbooks and essays he wrote, and the example he set of a scholar who moved freely between pure theory and practical engineering. In Chinese science he is remembered as a universal mind of the old school and as a tireless advocate for the unity of knowledge.

== See also ==
* Engineering science
* Chinese Academy of Sciences
* Elasticity
* Tsinghua University

== References ==

<ref name="r1">Qian Weichang, Theory of Elastic Plates and Shells, Science Press, 1956.</ref>
<ref name="r2">Qian Weichang, Applied Mathematics and Engineering Science, Peking University Press, 1985.</ref>
<ref name="r3">Liu Renhuai, Qian Weichang and the Development of Mechanics in China, Science Press, 2012.</ref>
<ref name="r4">Zhang Zhuo, A History of Chinese Applied Mathematics, Higher Education Press, 2007.</ref>

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[[Category:Physics]]
[[Category:Science]]
[[Category:Contemporary China]]