Carmeliet

Contact

Dr. Ahmad Rafsanjani room EMPA BA 300.2
Postdoc Researcher at EMPA tel +41 058 765 4751
  fax
  email ahmad.rafsanjani@empa.ch

raahmad@ethz.ch


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Profile

Ahmad Rafsanjani received his degree in Mechanical Engineering from Ferdowsi University of Mashhad (Iran) in 2006. He got his Master of Science in Mechanical Engineering from Iran University of Science and Technology in 2009. In his master research project, he focused on development of analytical methods for 3D vibration analysis of functionally graded (FGM) structures under moving loads using linear theory of elasticity. He joined EMPA in December 2009 and began his doctorate study at ETH Zurich. The topic of his PhD study is "Multiscale poroelastic model: bridging the gap from cellular to macroscopic scale" which will focus on computational modeling of mechanical and moisture related behavior of cellular porous solids, i. e. softwoods. This project is part of SNF Sinergia Project on "Multiscale analysis of coupled mechanical and moisture behavior of wood".


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PhD: Multiscale poroelastic model: bridging the gap from cellular to macroscopic scale

Wood is a natural resource of Switzerland, with significant applications in material production, building construction and civil engineering. In use, wood is mainly jointly subjected to mechanical and moisture loads and inappropriate loading of wood can result in mechanical damage and biodegradation. Thus, better knowledge of the hygro-mechanical behavior of wood is the fundament of the better design of new, durable structures and longer lives of existing ones. In addition, the understanding of cellular materials opens the door to the development of new materials.

Hierarchical structure of wood at macro-, micro- and nanoscales

Many natural materials show a hierarchical structure which impacts their mechanical behavior. In addition, the hygro-expansion properties of wood due to wetting (swelling) or drying (shrinkage) is highly influenced by the hierarchical structure of the material. The main aim in this project is to increase the insight into the material behavior from cellular and sub-cell level to macroscopic scale considering the moisture-mechanical coupling. The challenge remains however to find suitable homogenization techniques and relevant boundary conditions at each scale which give a physical explanation of the coupled mechanical and moisture behavior such as swelling anisotropy and hysteresis.

Wood cells (left) and corresponding representative volume element (right)


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Publications

Thesis

RAFSANJANI A, Multiscale poroelastic model: bridging the gap from cellular to macroscopic scale, ETH Dissertation No. 20821, Swiss Federal Institute of Technology (ETH Zurich), Switzerland. DOI

Peer-reviewed Journal Publications
14. RAFSANJANI A, LANVERMANN C, NIEMZ P, CARMELIET J, DEROME D: Multiscale analysis of free swelling of Norway spruce. Composites Part A 54:70-78, 2013 DOI
13. RAFSANJANI A, DEROME D, GUYER RA, CARMELIET J: Swelling of cellular solids: from conventional to re-entrant honeycombs. Applied Physics Letters 102:211907, 2013 DOI
12. RAFSANJANI A, DEROME D, CARMELIET J: Micromechanics investigation of hygro-elastic behavior of cellular materials with multi-layered cell walls. Composite Structures 95:607-611, 2013 DOI
11. RAFSANJANI A, DEROME D, CARMELIET J: The role of geometrical disorder on swelling anisotropy of cellular solids. Mechanics of Materials 55:49-59, 2012 DOI
10. DEROME D, RAFSANJANI A, PATERA A, GUYER RA, CARMELIET J: Hygromorphic behaviour of cellular material: hysteretic swelling and shrinkage of wood probed by phase contrast X-ray tomography. Philosophical Magazine 92:3680-3698, 2012 DOI
9. RAFSANJANI A, DEROME D, WITTEL F K, CARMELIET J: Computational up-scaling of anisotropic swelling and mechanical behavior of hierarchical cellular materials. Composites Science and Technology 72:744751, 2012 DOI
8. HASHEMINEJAD SM, RAFSANJANI A, Two-dimensional elasticity solution for transient response of simply supported beams under moving loads, Acta Mechanica 217:205218, 2011 DOI
7. ABBASION S, RAFSANJANI A, AVAZMOHAMMADI R, FARSHIDIANFAR A, Free vibration of microscaled Timoshenko beam, Applied Physics Letters 95:143122, 2009 DOI
6. RAFSANJANI A, ABBASION S, FARSHIDIANFAR A, IRANI N, Investigation of thermal and viscous effects in sheet metal blanking process, International Journal of Advanced Manufacturing Technology 45:459-469, 2009 DOI
5. ABBASION S, RAFSANJANI A, IRANI N, FARSHIDIANFAR A, Stress analysis for a coated fiber embedded in an infinite matrix subjected to body force, European journal of Mechanics, A/Solid 28:777-785, 2009 DOI
4. HASHEMINEJAD SM, RAFSANJANI A, Three-dimensional vibration analysis of thick FGM plate strips under moving line loads, Journal of Mechanics of Advanced Materials and Structures 16:417-428, 2009 DOI
3. RAFSANJANI A, ABBASION S, FARSHIDIANFAR A, MOEENFARD H, Nonlinear dynamic modeling of surface defects in rolling element bearing systems, Journal of Sound and Vibration 319:1150-1174, 2009 DOI
2. FARSHIDIANFAR A, MOEENFARD H, RAFSANJANI A, Frequency response calculation of nonlinear torsional vibration in gear systems, Journal of Multi‐body Dynamics, Proceeding of IMECHE Part K 221:49-60, 2008 DOI
1. ABBASION S, RAFSANJANI A, FARSHIDIANFAR A, IRANI N, Rolling element bearings multi-fault classification based on the wavelet de-noising and support vector machine, Mechanical Systems and Signal Processing 21:2933-2945, 2007 DOI

Conference proceedings

5. RAFSANJANI A, DEROME D, CARMELIET J, A poromechanics approach to predict the effective swelling behavior of cellular materials, Poromechanics V:Proceedings of the Fifth Biot Conference on Poromechanics (Austria, Vienna, July 10-12, 2013), 739-748, 2013 DOI
4. RAFSANJANI A, DEROME D, GUYER RA, CARMELIET J, Anisotropic Swelling Behavior of Cellular Solids, The 18th International Conference on Nonlinear Elasticity in Materials, Ascona, Switzerland, 9-14 June 2013.
3. RAFSANJANI A, PATERA A, DEROME D, CARMELIET J, Multiscale modeling of anisotropic hygro-mechanical behavior of natural cellular composites, Mechanics of Nano, Micro and Macro Composite Structures, Politecnico di Torino, Turin, Italy, 18-20 June 2012.
2. RAFSANJANI A, DEROME D, CARMELIET J, Effective poroelastic properties of softwood in relation to moisture induced swelling, Interpore 2012, Purdue University, West Lafayette, USA, May 2012.
1. RAFSANJANI A, DEROME D, HERRMANN HJ, CARMELIET J, Multiscale computational homogenization for the hygro-mechanical analysis of growth rings in softwoods, COST Action FP0802, Vila Real, Portugal, April 27-28, 2011. (presentation)


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