A finite element model for cryosurgery with coupled phase change and thermal stress aspects

2008 ◽  
Vol 44 (5) ◽  
pp. 288-297 ◽  
Author(s):  
Baohong Yang ◽  
Richard G. Wan ◽  
Ken B. Muldrew ◽  
Bryan J. Donnelly
2012 ◽  
Vol 443-444 ◽  
pp. 751-756
Author(s):  
Li Jun Suo ◽  
Xia Guang Hu

In China, it is fact that porous concrete base has been used in the construction of asphalt pavement in recent years because porous concrete base has good performance. However, Reasonable design method has not been put forward so far. Therefore, it is necessary to analyze load stress and thermal stress of asphalt pavement which includes porous concrete base in order to put forward theoretical basis for pavement design method. In the paper, three–dimension finite element model of asphalt pavement, which includes porous concrete base and asphalt surface, is created for the purpose of studying load stress and thermal stress of porous concrete base in asphalt pavement. Based on numerical method of three–dimension finite element model, finite element software, such as ANSYS, is employed to study load stress and thermal stress of porous concrete base in asphalt pavement. After that, the effect of different factors on stress is studied, and the factors include thickness of surface, thickness of base and ratio of base’s modulus to foundation’s modulus. Finally, calculation results for stress are compared with each other, and it shows that load stress of porous concrete base decreases with increase of base’s thickness, while thermal stress of porous concrete base increases with increase of base’s thickness. Load stress and thermal stress of porous concrete base decrease with increase of surface’s thickness. Load stress and thermal stress of porous concrete base increase with increase of ratio of base’s modulus to foundation’s modulus.


2013 ◽  
Vol 860-863 ◽  
pp. 1770-1781
Author(s):  
Dong Mei Ji ◽  
M. H. Herman Shen ◽  
Shi Hua Yang ◽  
Gang Xia

A thorough investigation on the effect of a 320MW steam turbine rotor notch fillet radius on thermal and mechanical stresses during start up is presented. The approach consists of a shape design and analysis procedure which incorporates a finite element model. The finite element model is used to characterize the radius of the rotor notch fillet for ensuring the designed thermal and mechanical stress state/pattern and associated deflection during start-up. The results indicate that the notch fillet radius r has significant impact on the total stress of the rotor, in particular on thermal stress. It is determined that the thermal stress is decreased as the notch fillet radius r increases to a critical value. However, the thermal stress becomes saturated as the radius is increased to values larger than the critical value. The results also indicate that the rotor notch fillet radius has little effect on the deflection of the rotor during start-up. This investigation could be very useful to designers for construction of the design guidelines for steam turbine rotors.


2013 ◽  
Vol 361-363 ◽  
pp. 1699-1702
Author(s):  
Li Jun Suo ◽  
Bing Gang Wang

Both thermal stress and load stress, which are caused by temperature change and traffic loading, are important parameters used in the analysis of the new asphalt pavement design. In order to study the stress of asphalt pavement of lean concrete base, first of all, threedimension finite element model of the asphalt pavement of lean concrete base is established. The main objectives of the paper are investigated. One is calculation for stress of asphalt surface, and the other is calculation for stress of lean concrete base. The results show that load stress of lean concrete base increases quickly with the increase of load. Thermal stress of lean concrete base increases with the increase of thickness of base. Asphalt surface is in the state of compression. Maximum shearing stress decreases with the increase of thickness of asphalt surface.


2005 ◽  
Vol 22 (4) ◽  
pp. 773 ◽  
Author(s):  
J. H. Brusche ◽  
H. P. Urbach ◽  
A. Segal

2010 ◽  
Vol 78 (1) ◽  
Author(s):  
Antoinette M. Maniatty ◽  
G. S. Cargill ◽  
Laura E. Moyer ◽  
Chia-Ju Yang

An X-ray microbeam study and a polycrystal finite element model of a 10×10 μm2 section of a 1 μm thick polycrystalline aluminum film on a silicon substrate are used to investigate the effect of microstructure on thermal stress variability. In the X-ray microbeam study, the grain orientations and deviatoric elastic strain field are measured at the subgrain level in the film during and after two thermal cycles. A finite element model of the observed grain structure is created and modeled with an elastoviscoplastic crystal constitutive model that incorporates film thickness and grain size effects as well as dislocation entanglement hardening. The experimental and simulation results are compared at both the film and subgrain scales. While the experiment and model agree fairly well at the film level, the experimental results show much greater elastic strain variability than the simulations. In considering the grain size effect, the experiment and model both predict a similar Hall–Petch coefficient, which is consistent with literature data on free standing aluminum thin films.


Author(s):  
Zhenhua Guo ◽  
Zhaoyan Zhang ◽  
Biqing Sheng ◽  
Wen Peng

A displacement based 3D finite element model is developed to simulate thermal stress induced by high temperature and temperature gradient during diesel particulate filter (DPF) regeneration. The temperature field predicted by 3D regeneration model from previous work is used as input. This finite element model agrees well with commercial software. It is a self-contained package capable of implementing meshing body, assembling global stiffness matrix and solving final equilibrium equations. Numerical simulation indicates that it is peak temperature rather than temperature gradient that leads to higher compressive thermal stress during regeneration. The maximum stress always appears at the channel corner located at the end of DPF. Parametric studies are performed to investigate the effects of DPF design on pressure drop, regeneration temperature, and thermal stress. This model provides insights into the complicated DPF working mechanism, and it can be used as design tools to reduce filter pressure drop while enhance its short term and long term durability.


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