YIN Yajun,Professor, Doctor, Department of Engineering Mechanics, School of Aerospace
B.S., Hydraulic Engineering, Tsinghua University, 1985
M.S., Solid Mechanics, Tsinghua University, 1987
Ph.D., Mechanical Engineering, Hiroshima University, Japan, 1998
Assistant professor, Lecturer, Tsinghua University, 1988-1999
Associate Professor, Tsinghua University, 1999-2004
Full Professor, Tsinghua University, 2004-date
Research Fellowship, Delft University, 1992-1993
Research Fellowship, Research Institute of IHI, Japan, 2000-2001
Research Interests
Biomechanics, Cell Mechanics, Bionic Mechanics, Fractal Geometry and Mechanics in Biology, Micro/Nano Mechanics
Research Description 
  In recent ten years, Professor Yin's research group is mainly interested in Biomechanics, Cell Mechanics, Bionic Mechanics, Fractal Geometry and Mechanics in Biology, Micro/Nano Mechanics. The general equilibrium theory, stability theory and shape transition mechanism for biomembranes are established. The second class gradient operator (or shape gradient operator) on 2D Riemann curved surfaces are defined. The second class of integral theorems on curved surfaces is proved. The equivalences between the Steiner minimal trees and the stable equilibrium biomembrane nanotube networks or spontaneously Y-branched carbon nanotubes are confirmed. The concept of super carbon nanotube is defined. The geometric characteristics of the fractal super tubes are made clear. The concept of fractal super fibers is suggested. The geometric invariabilities and the growth and topological evolution modes of the fractal super fibers are disclosed.  
Selected Publications
(1)Mechanics of biomembranes
[1] Y. Yin, J. Wu, Shape gradient: a driving force induced by space curvatures, International Journal of Nonlinear Sciences and Numerical Simulation, 11(4), 259-267, July. 2010.
[2] Y. Yin, Y. Chen, D. Ni, H. Shi and Q. Fan, Shape equations and curvature bifurcations induced by inhomogeneous rigidities in cell membranes, Journal of Biomechanics, Vol.38, 2005, 1433-1440.
[3] Y. Yin, J. Yin, C. Lv, Equilibrium theory in 2D Riemann manifold for heterogeneous biomembranes with arbitrary variational modes, Journal of Geometry and Physics 58 (2008) 122–132.
[4] Y. Yin, J. Yin and D. Ni, General mathematical frame for open or closed biomembranes: equilibrium theory and geometrically constraint equation, Journal of Mathematical Biology, vol.51, 2005, 403-413.
[5] Yajun Yin, Cunjing Lv, Equilibrium theory and geometrical constraint equation for two-component lipid bilayer vesicles, J. Biol. Phys. (2008) 34:591–610.
[6] Y. Yin, H.-Y. Yeh and J. Yin, Stability similarities between shells, cells and nano carbon tubes, IEE Proc.-Nanobiotechnology, Vol. 153, No. 1, 2006.
(2) Geometry of biomembranes
[1] Y. Yin and J. Yin, Geometric conservation laws for cells or vesicles with membrane nanotubes or singular points, Journal of Nanobiotechnology 2006, 4, 6(5pp).
[2] Y. Yin, Integral theorems based on a new gradient operator derived from biomembranes (part I): Fundamentals, Tsinghua Science and Technology, Vol.10, No.3, 2005, pp372-375.
[3] Y. Yin, Integral theorems based on a new gradient operator derived from biomembranes (part II): Applications, Tsinghua Science and Technology, Vol.10, No.3, 2005, pp376-380.
[4] Y. Yin and J. Yin, Geometric constraint equations and geometrically permissible conditions for vesicles, Chinese Physics Letters, Vol.21, No.10, 2004, 2057-2058.
[5] YIN Yajun, WU Jiye, Fan Qinshan and Huang Kezhi, Invariants under parallel mapping, Tsinghua Science and Technology, Vol.14, No.5, 2009.
[6] YIN Yajun, WU Jiye, YIN Jie, Symmetrical fundamental tensors, differential operators and integral theorems in differential geometry, Tsinghua Science and Technology, Vol.13, No.2, 2008, 121-126.
[7] YIN Ya-jun, WU Ji-ye, HUANG Ke-zhi, FAN Qin-shan, From the second gradient operator and second class of integral theorems to Gaussian or spherical mapping invariants, Appl. Math. Mech., 2008, 29(7):855-862
(3) Fractal mechanics and fractal geometry
[1] Ya-Jun Yin, Fan Yang, Qin-Shan Fan, Tong Zhang, Cell elements, growth modes and topology evolutions of fractal supper fibers, International Journal of Nonlinear Sciences and Numerical Simulation, 10(1), 1-12, Jan. 2009.
[2] Yajun YIN, Tong ZHANG, Fan YANG and Xinming QIU, Geometric conditions for fractal super carbon nanotubes with strict self-similarities, Chaos, Solitons and Fractals, 37 (2008) 1257–1266.
[3] Ya-Jun Yin, Fan Yang, Tong Zhang and Qin-Shan Fan, Growth condition and growth limit for fractal super fibers and fractal super tubes, International Journal of Nonlinear Sciences and Numerical Simulations 2008, Vol.9, No.1, 96-102.
[4] Yin Y, Yang F, Fan Q S. Isologous Fractal Super Fibers or Fractal Super Lattices, Int. J. Electrospun Nanofibers and Applications, 2008, 2(3): 193-201.
[5] Yin Y, He B, Yang F, Fan Q S. Centroid Evolution Theorem Induced from Fractal Super Fiber or Fractal Super Snowflakes, International Journal of Nonlinear Sciences & Numerical Simulation, 2009, 10(5).
[6] Yajun Yin, Fan Yang, Ying Li and Qinshan Fan, Fractal geometry and topology abstracted from hair fibers, Applied Mathematics and Mechanics, 2009,30(8): 983-990
[7] Yajun Yin, Fan Yang, Qinshan Fan, The growth kinematics of fractal super snowflakes, Chinese Science Bulletins, 2009,54(22):3433-3440
[8] Yajun Yin, Ying Li, Fan Yang and Qinshan Fan, Multiple-cell elements and regular multifractals, Applied Mathematics and Mechanics, 2010,31(1): 55-65
[9] Ying Li, Yajun Yin, Qinshan Fan, Fan Yang: From Fractal Super Fibers to Multi-fractal Super Fibers and Wool Fibers with Exceptional Mechanical Properties, Materials Science and Technology. 2010, 26(11): 1323
(4) Mechanics of super carbon nanotubes
[1] Yin Y., Chen Y., Yin J. and Huang K., Geometric conservation laws for perfect Y-branched carbon nanotubes, Nanotechnology, 17 (2006) 4941–4945.
[2] Ying Li, XinMing Qiu, Fan Yang, Yajun Yin*, Qinshan Fan, Stretching-dominated deformation mechanism in a super square carbon nanotube network, Carbon, 47 (2009), 812-819.
[3] Yuli Chen, Yajun Yin*, Yonggang Huang, and Keh-Chih Hwang, Atomistic Simulations of the Nonlinear Deformation and Damage Modes of Super Carbon Nanotubes, Journal of Computational and Theoretical Nanoscience Vol.6(1), 41–45, 2009
[4] Ying Li, XinMing Qiu, Fan Yang, Xi-ShuWang and Yajun Yin*, Ultra-high sensitivity of super carbon-nanotube-based mass and strain sensors, Nanotechnology 19 (2008), 19 (2008) 165502 (6pp)
[5] Ying Li, Xinming Qiu, Fan Yang, Xishu Wang, Yajun Yin*, Effective modulus of super carbon nanotubes predicted by molecular structure mechanics, Nanotechnology, 19 (2008) 225701 (7pp).
[6] Fan Yang, XinMing Qiu, Ying Li, Yajun Yin*, Qinshan Fan, Specific heat of super carbon nanotube and its chirality independence, Physics Letters A, 372 (2008) 6960–6964.
[7] Ying Li, XinMing Qiu, Fan Yang, Xi-Shu Wang, Yajun Yin*, Qinshan Fan, Chirality independence in critical buckling forces of super carbon nanotubes, Solid State Communications, 148 (2008) 63–68
[8] Ying Li, XinMing Qiu, Fan Yang, Xi-ShuWang, Yajun Yin* and Qinshan Fan, A comprehensive study on the mechanical properties of super carbon nanotubes, J. Phys. D: Appl. Phys. 41 (2008) 155423 (6pp).
[9] CHEN Yu-Li, LIU Bin, YIN Ya-Jun*, HUANG Yong-Gang, HWUANG Keh-Chih, Nonlinear Deformation Processes and Damage Modes of Super Carbon Nanotubes with Armchair-Armchair Topology, Chinese Physics Letters, Vol. 25, No. 7 (2008) 2577-2580
[10] Li, Ying; Qiu, Xinming; Yin, Yajun; Yang, Fan; Fan, Qinshan . The elastic buckling of super-graphene and super-square carbon nanotube networks. Physics Letters A, 2010. Volume 374, Issue 15-16, p. 1773-1778.
[11] Yajun Yin, Qinshan Fan, Fan Yang, Ying Li: Super Carbon Nanotubes, Fractal Super Tubes and Fractal Super Fibers, Materials Science and Technology 2010 VOL 26 NO 11 1327
(5) Bionic Mechanics
[1] ZHAO HongXiao, YIN YaJun & ZHONG Zheng, Micro and nano structures and morphologies on the wing veins of dragonflies, Chinese Sci Bull, July 2010 Vol.55 No.19: 1993−1995
[2] ZHAO HongXiao, YIN YaJun & ZHONG Zheng, Nano Fibrous Multilayered Composites in Pterostigma of Dragonfly,Chinese Sci Bull, 2010 Vol.55 No.18 , 1856-1858 (in Chinese)