Tsinghua University (THU)

Situated on several former royal gardens of the Qing Dynasty, Tsinghua University was established in 1911 originally as a preparatory school for students supported by the government to study in universities in the United States. With a splendid legacy accumulated over the past 90 years, THU has retained its character and charm, becoming the national centre for training engineers and scientists with both professional proficiency and personal integrity Tsinghua University has become a comprehensive university since 1980’s. There are currently 17 schools and 57 departments, and 32,800 full-time students, including 14,900 undergraduates and 17,900 graduate students (8,600 master's degrees candidates and 4,600 doctoral candidates), and 7,230 faculty and staff members (over 1200 full professors and 1,100 associate professors). Among over 170,000 students who have graduated from Tsinghua since its founding are many outstanding scholars, eminent entrepreneurs and great statesmen remembered and respected by their fellow Chinese citizens. As one of China’s most renowned universities, Tsinghua has become an important institution for fostering talent and scientific research.

The School of Aerospace at Tsinghua University was founded in 2004, currently with 80 faculty members. The School has the strongest teaching and research capacity in fluid mechanics in China.

According to the recent government disciplinary assessments, THU ranks first in fluid mechanics. The main goal of the School is to educate highly qualified scientists and engineers. Out of the 380 graduate students, there are 180 Doctoral and 200 Master students. The School of Aerospace has important and wide influences on the academic field in the world and on the engineering field in China, because of the long histories of the Dept. of Aeronautics and Dept. of Engineering Mechanics.

The researches in the school concern the fundamental knowledge and engineering application for aerospace engineering that gives emphases on nine areas: (1) solid mechanics, (2) fluid mechanics, (3) engineering dynamics, (4) engineering thermo-physics, (5) biomechanics and bionics, (6) aircraft and spacecraft, (7) propulsion engineering, (8) aerospace equipment and environment, and (9) Aerospace information.

The school has widely national and international research cooperation and academic exchanges with many famous universities and institutes in USA, UK, Germany, France, Italy, Canada, Russian, Japan, Korea and Hong Kong etc. SA has also closely related with the key national laboratories and institutes. Two departments of the School will be involved in the project:

The Department of Engineering Mechanics, under Prof. Zhuo Zhuang; and the Institute of Engineering Dynamics, under Prof. Xiong Zhang.

The Department of Engineering Mechanics of Tsinghua University will focus on sharing its knowledge on the extended finite element method (XFEM). XFEM was developed to ease difficulties in solving problems with localized features that are not efficiently resolved by mesh refinement. One of the initial applications was the modelling of fractures in a material. In this original implementation, discontinuous basis functions are added to standard polynomial basis functions for nodes that belonged to elements that are intersected by a crack to provide a basis that included crack opening displacements. A key advantage of XFEM is that in such problems the finite element mesh does not need to be updated to track the crack path. Subsequent research has illustrated the more general use of the method for problems involving singularities, material interfaces, regular meshing of microstructural features such as voids, and other problems where a localized feature can be described by an appropriate set of basis.

This project provides an opportunity to take a step further in the development of the extended Finite Element Method and the Material Point Method. Jointly with the expertise of European partners, this project aims at using XFEM and meshfree methods to analyse and simulate some complex problems in the fluid - soil structure interaction to estimate the safety of infrastructures in hazard induced by water.

The School of Aerospace of Tsinghua University has a long tradition in R&D partnerships involving European partners. More specifically, with Swansea University there is a long tradition of scientific cooperation, as shown by joint projects supported by several funding agencies (such as the 973 Program of the Ministry of Science and Technology of China, the International Program of the National Science Foundation of China or the Royal Society in UK) or by the series of joint workshops whose first edition took place in China in July 2012, with a second edition planned for 2013 in United Kingdom. The partnership with CIMNE dates back to 2006, when Tsinghua became a member of the Aerochina Project, funded by the 6th Framework Programme (coordinated by CIMNE on the European side). Since then, cooperation went on under the umbrella of EU-China bilateral RTD projects such as Aerochina 2, GRAIN, MARS and COLTS. Not only on the research field Tsinghua hasstrong ties to Swansea University and CIMNE, but also on the academic area, since Tsinghua became last year a Third Country Partner Institution of Erasmus Mundus Consortium of Master Degree in Computational Mechanics. All together lay the foundations to establish a powerful platform to promote cooperation in areas of expertise that are prioritised by both China and the European Research Area (such as Natural Disaster Prevention). Last, but not least, the IRSES funding scheme provides an invaluable opportunity to expand this expertise exchange platform to other regional areas, which are also of strategic importance in a globalized background, such as Latin America.

The Institute of Disaster Prevention and Mitigation (IDPME) of the School of Civil Engineering at Tsinghua University will provide expertise and technical support to integrate the knowledge of the School of Aerospace in the field of disaster prevention and mitigation. The IDPME dates back to the 1960s and currently possesses the primary attributes of a world-class institute: excellent researchers, advanced facilities, innovative academic achievements, and unique research interests. The IDPME currently offers six courses for undergraduate students: Disaster and Prevention, Computer Drawing in Engineering, Fundamentals of Civil Engineering CAD Technology, Objected-Oriented Programming, Structural Reliability, and Structural Design for Fire Safety. The IDPME also offers ten courses for graduate students: CAE in Civil and Building Engineering, Object-Oriented Design Method, Structural Dynamics, Fundamentals of Seismic Design, Finite Element Analysis of Reinforced Concrete, Catastrophology, Fire Safety Engineering of Building Structures, Composite Structures (Concrete Filled Steel Tubes), Theory and Engineering on System Reliability and Advanced Dynamic of Structures. CAD in Civil Engineering is selected as both the Excellent Course of Beijing and the Excellent Course of Tsinghua University, and Structural Dynamics and Finite Element Analysis of Reinforced Concrete Structures are selected as the Excellent Course of Tsinghua University.

Projects related to this TCAiNMaND proposal:

XFEM

Development of the extended finite element method (XFEM) to simulate the fracture in 2D/3D solid and shell structure. This method allows the simulation of the initiation, branching and interaction of cracks. The defect energy theory and discrete dislocation dynamics method have been proposed in order to describe the evolution of phenomena such as dislocation nucleation, multiplication, starvation and annihilation. Funded by National Science Foundation of China (NSFC), grant number is 11132006 (granted in 2011, starting on 01/2012 until 12/2016). And by the 973 Program of the Ministry of Science and Technology (MOST), grant number is 2010cB631005.

Key Algorithms in Modelling Structural Damage under Shock Load

The project is aimed at developing methods to build dynamic and mesoscopic constitutive models for materials modelling under high strain condition, and at providing a unified theoretical framework on numerical analysis of multi-material response analysis under the impact of the explosion loads. In this way, it will develop a simulation platform to assess the damage of complex structures in explosion and desintegration processes, and it will also strive to provide tools to protect such infrastructres and grant the public safety. Funded by the 973 Program of the Ministry of Science and Technology. Project ID: 2010CB832701, awarded in 2010

Codes developed by THU available to the projects are XFEM and 3DMPM.

Description of the codes:

• XFEM

The XFEM (extended finite element method) has a lot of advantages over other numerical methods to resolve discontinuities across quasi-static interfaces due to the jump in fluidic parameters or surface tension. However, singularities corresponding to enriched degrees of freedom (DOFs) embedded in XFEM arise in the discrete pressure Poisson equations. In this paper, constraints on these DOFs are derived from the interfacial equilibrium condition and introduced in terms of stabilized Lagrange multipliers designed for non-boundary-fitted meshes to address this issue. Numerical results show that the weak and strong discontinuities in pressure with straight and circular interfaces are accurately reproduced by the constraints. Comparisons with the SUPG/PSPG (streamline upwind/pressure stabilizing Petrov-Galerkin) method without Lagrange multipliers validate the applicability and flexibility of the proposed constrained algorithm to model problems with quasi-static interfaces.

• 3DMPM

3D explicit parallel MPM code, MPM3D, developed using object-oriented design by C++ program language with Qt, VTK and CMake, and can be run on different platforms including Windows, Linux and Mac OS. Several constitutive models, equations of state (EOS) and failure models have been implemented in our MPM3D code, such as Johnson-Cook material model for metal, Holmqusit-Johnson-Cook model and RHT model for concrete, JH2 model for ceramic, Drucker- Prager model for soil and rock, Mooney-Rivlin model for rubber, Gurson model for elastic-plastic solid with void, Polynomial EOS, Jones-Wilkins-Lee EOS and Gruneisen EOS. Several numerical examples such as shock tube, explosively driven flyer, shaped charge, debris cloud, projectile penetration of steel plate and reinforced concrete, slope slide, metal cutting are presented to demonstrate the application of MPM3D, which shows that MPM3D is a powerful tool for impact and explosion simulation.

Category: TSINGHUA