TY  - JOUR
A1  - Nguyen, Nhu Huynh
A1  - Duong, Minh Tuan
A1  - Tran, Thanh Ngoc
A1  - Pham, Phu Tinh
A1  - Grottke, O.
A1  - Tolba, R.
A1  - Staat, Manfred
T1  - Influence of a freeze–thaw cycle on the stress–stretch curves of tissues of porcine abdominal organs
JF  - Journal of Biomechanics
N2  - The paper investigates both fresh porcine spleen and liver and the possible decomposition of these organs under a freeze–thaw cycle. The effect of tissue preservation condition is an important factor which should be taken into account for protracted biomechanical tests. In this work, tension tests were conducted for a large number of tissue specimens from twenty pigs divided into two groups of 10. Concretely, the first group was tested in fresh state; the other one was tested after a freeze-thaw cycle which simulates the conservation conditions before biomechanical experiments. A modified Fung model for isotropic behavior was adopted for the curve fitting of each kind of tissues. Experimental results show strong effects of the realistic freeze–thaw cycle on the capsule of elastin-rich spleen but negligible effects on the liver which virtually contains no elastin. This different behavior could be explained by the autolysis of elastin by elastolytic enzymes during the warmer period after thawing. Realistic biomechanical properties of elastin-rich organs can only be expected if really fresh tissue is tested. The observations are supported by tests of intestines.
KW  - Autolysis
KW  - Decomposition
KW  - Freeze–thaw process
KW  - Spleen
KW  - Liver
Y1  - 2012
U6  - http://dx.doi.org/10.1016/j.jbiomech.2012.07.008
SN  - 1873-2380
VL  - 45
IS  - 14
SP  - 2382
EP  - 2386
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Pham, Phu Tinh
A1  - Staat, Manfred
T1  - An Upper Bound Algorithm for Limit and Shakedown Analysis of Bounded Linearly Kinematic Hardening Structures
JF  - Limit State of Materials and Structures : Direct Methods 2. Saxcé, Géry de (Hrsg.)
Y1  - 2013
SN  - 978-94-007-5424-9
SP  - 71
EP  - 87
PB  - Springer
CY  - Dordrecht
ER  - 
TY  - JOUR
A1  - Pham, Phu Tinh
A1  - Staat, Manfred
T1  - FEM-based shakedown analysis of hardening structures
JF  - Asia Pacific journal on computational engineering
N2  - This paper develops a new finite element method (FEM)-based upper bound algorithm for limit and shakedown analysis of hardening structures by a direct plasticity method. The hardening model is a simple two-surface model of plasticity with a fixed bounding surface. The initial yield surface can translate inside the bounding surface, and it is bounded by one of the two equivalent conditions: (1) it always stays inside the bounding surface or (2) its centre cannot move outside the back-stress surface. The algorithm gives an effective tool to analyze the problems with a very high number of degree of freedom. Our numerical results are very close to the analytical solutions and numerical solutions in literature.
Y1  - 2014
U6  - http://dx.doi.org/10.1186/2196-1166-1-4
SN  - 2196-1166 (E-Journal)
IS  - 1
SP  - Article No. 4
PB  - SpringerOpen
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Pham, Phu Tinh
A1  - Vu, Khoi Duc
A1  - Tran, Thanh Ngoc
A1  - Staat, Manfred
T1  - A primal-dual algorithm for shakedown analysis of elastic-plastic bounded linearly kinematic hardening bodies
Y1  - 2010
N1  - ECCM 2010, IV European Conference on Computational Mechanics, Paris, France, May 16-21, 2010.
SP  - 1
EP  - 7
ER  - 
TY  - JOUR
A1  - Tran, Thanh Ngoc
A1  - Pham, Phu Tinh
A1  - Vu, D. K.
A1  - Staat, Manfred
T1  - Reliability Analysis of Inelastic Shell Structures Under Variable Loads
JF  - Limit States of Materials and Structures : Direct Methods / Hrsg. Dieter Weichert; Hrsg. Alan Ponter
Y1  - 2009
SN  - 978-1-4020-9633-4
SP  - 135
EP  - 156
PB  - Springer Netherland
CY  - Berlin
ER  -