The Plastic Ratcheting of Thin Cylindrical Shells Subjected to Axisymmetric Thermal and Mechanical Loading

1987 ◽  
Vol 109 (4) ◽  
pp. 387-393 ◽  
Author(s):  
S. Karadeniz ◽  
A. R. S. Ponter ◽  
K. F. Carter
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Mechanical Loading ◽  
Material Properties ◽  
Thermal Loading ◽  
Cylindrical Shells ◽  
Temperature Fields ◽  
Mechanical Loads ◽  
Element Technique ◽  
The Relationship

The paper discusses the relationship between material properties and structural ratcheting for thin cylindrical shells subjected to severe thermal loading. The need to understand this problem arises in the design of Sodium Cooled Fast Reactors. A sequence of shakedown solutions are presented using a finite element technique [13]. It is shown that for tubes subject to moving temperature fields, ratcheting can occur even when no mechanical loads are applied and the material strongly cyclically hardens. Only small movements are required. Stationary thermal cycling is less likely to produce ratcheting. The calculations are compared with two sets of experimental data, which serve to confirm these conclusions.

Analysis and design of thermo-mechanical interfaces

2012 ◽  
Vol 60 (2) ◽  
pp. 205-213
Author(s):  
K. Dems ◽  
Z. Mróz
Keyword(s):  
Optimality Conditions ◽  
Mechanical Loading ◽  
Material Properties ◽  
Structural Response ◽  
External Boundary ◽  
Mechanical Loads ◽  
Internal Interface ◽  
Analysis And Design ◽  
First Order ◽  
Mechanical Nature

Abstract. An elastic structure subjected to thermal and mechanical loading with prescribed external boundary and varying internal interface is considered. The different thermal and mechanical nature of this interface is discussed, since the interface form and its properties affect strongly the structural response. The first-order sensitivities of an arbitrary thermal and mechanical behavioral functional with respect to shape and material properties of the interface are derived using the direct or adjoint approaches. Next the relevant optimality conditions are formulated. Some examples illustrate the applicability of proposed approach to control the structural response due to applied thermal and mechanical loads.

Failure Prediction of Flip Chip Packages Using Finite Element Technique

2002 ◽  
Author(s):  
Abm Hasan ◽  
H. Mahfuz ◽  
M. Saha ◽  
S. Jeelani
Keyword(s):  
Finite Element ◽  
Flip Chip ◽  
Thermal Loading ◽  
Failure Modes ◽  
Element Model ◽  
Thermally Induced ◽  
Operational Life ◽  
Flip Chip Assembly ◽  
The Individual ◽  
Element Technique

Flip-chip electronic package undergoes thermal loading during its curing process and operational life. Due to the thermal expansion coefficient (CTE) mismatch of various components, the flip-chip assembly experiences various types of thermally induced stresses and strains. Experimental measurement of these stresses and strains is extremely tedious and rigorous due to the physical limitations in the dimensions of the flip-chip assembly. While experiments provide accurate assessment of stresses and strains at certain locations, a parallel finite element (FE) analysis and analytical study can complementarily determine the displacement, strain and stress fields over the entire region of the flip-chip assembly. Such combination of experimental, finite element and analytical studies are ideal to yield a successful stress analysis of the flip-chip assembly under the various loading conditions. In this study, a two-dimensional finite element model of the flip-chip consisting of the silicon chip, underfill, solder ball, copper pad, solder mask and substrate has been developed. Various stress components under thermal loading condition ranging from −40°C to 150°C have been determined using both the finite element and analytical methods. Stresses such as (σ11, σ12, ε12 etc. are extracted and analyzed for the individual components as well as the entire assembly, and the weakest positions of the flip-chip have been discovered. Detailed description of FE modeling is presented and the different failure modes of chip assembly are discussed.

Computation of Ratchet Limits for Structures Subjected to Cyclic Loading and Temperature

2002 ◽  
Author(s):  
A. R. S. Ponter ◽  
H. Chen ◽  
M. Habibullah
Keyword(s):  
Finite Element ◽  
Cyclic Loading ◽  
Mechanical Loading ◽  
Limit Theorems ◽  
Thermal Loading ◽  
Loading History ◽  
Cyclic Thermal Loading ◽  
Elastic Plastic ◽  
Plastic Structure ◽  
Shakedown Limit

The paper discusses methods of evaluating the ratchet limit for an elastic/plastic structure subjected to cyclic thermal and mechanical loading. A recently developed minimization theorems by Ponter and Chen [2] provides a generalization of the shakedown limit theorems for histories of load in excess of shakedown. This allows the development of programming methods that locate the ratchet boundary in excess of shakedown. Examples of applications are provided including the performance of a cracked body subjected to cyclic thermal loading. Finally, the theory is used to discuss Kalnins’ [4] proposal that short cut finite element solutions may be used to assess whether a particular loading history lies within a ratchet limit.

scholarly journals Dynamic behaviors of cylindrical shells with geometric imperfection

2019 ◽  
Vol 293 ◽  
pp. 01003
Author(s):  
J F Jia ◽  
A D Lai ◽  
D L Rong ◽  
Z H Zhou ◽  
X S Xu
Keyword(s):  
Numerical Simulation ◽  
Finite Element Method ◽  
Finite Element ◽  
Cylindrical Shells ◽  
Vibrational Modes ◽  
Engineering Structures ◽  
Geometric Imperfections ◽  
Geometric Imperfection ◽  
Local Vibrational Modes ◽  
The Relationship

For finding out the relationship between vibrational modes and geometric imperfections, the dynamic behavior of cylindrical shells with a local imperfection is analyzed by using numerical simulation of finite element method in this paper. The results show that there are some differences in vibrational modes between cylindrical shells with and without imperfections. They appear that main corrugation of the mode of the higher orders for the shell with a local imperfection can be fastened on the region of the imperfection but the low order ones. The results also show that the vibrational modes of shells depend upon the size, shape and location of the imperfections. The local vibrational modes are discovered and are more obvious for the imperfection of the larger size. These results are helpful to the design of engineering structures.

MODELING OF ALKALI-SILICA REACTION IN A TWO-PHASED MATERIAL MODEL

2015 ◽  
Vol 76 (9) ◽  
Author(s):  
Zarina Itam ◽  
Hazran Husain
Keyword(s):  
Material Properties ◽  
Mesoscale Model ◽  
Damage Model ◽  
Material Model ◽  
Silica Content ◽  
Alkali Silica Reaction ◽  
Complex Phenomenon ◽  
Damage Propagation ◽  
Element Technique ◽  
The Relationship

Alkali-silica reaction causes major problems in concrete structures due to the rapidity of its deformation. Factors that affect ASR include the alkali and silica content, relative humidity, temperature and porosity of the concrete, making the relationship a complex phenomenon to be understood. Hence, the finite element technique was used to build models to study the damage propagation due to ASR. Seeing that ASR initializes in the mesoscopic regions of the concrete, the damage model for ASR at the mesoscale level is studied. The heterogeneity of the mesoscale model shows how difference in material properties between aggregates and the cementitious matrix facilitates ASR expansion. With this model mesoscopic, two-phased material model, the ASR phenomenon under thermo-chemo-hygro-mechanical loading can be understood.

The Finite Element Analysis of New Forged Coupler Knuckle

2013 ◽  
Vol 367 ◽  
pp. 122-125
Author(s):  
Guang Xin Wang ◽  
Xiang Shun Bu ◽  
Lin Jie Li ◽  
Li Li Zhu
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Direct Relationship ◽  
Element Analysis ◽  
Compression Load ◽  
The Finite Element Analysis ◽  
Simulation Results ◽  
Element Technique ◽  
Working Situation ◽  
Made In

As one of the most important load-bearing parts, coupler knuckle has a direct relationship with the safety in operation and reliability of the freight trains. A new forged coupler knuckle is made in order to meet the challenge to export ore train to Australia. Using the finite element technique, the stress characteristics of forged coupler knuckle under 1225kN load in tension and 1500kN compression load are evaluated. Simplify the load and boundary condition depend on the real working situation, the numerical simulation results coincide with experimental data.

Analytical evaluation of thermally induced residual stresses in ground components

2003 ◽  
Vol 217 (5) ◽  
pp. 471-482 ◽  
Author(s):  
D G Walsh ◽  
A A Torrance ◽  
J Tiberg
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Critical Temperature ◽  
Yield Strength ◽  
Residual Stresses ◽  
Material Properties ◽  
Analytical Evaluation ◽  
Simple Method ◽  
Thermally Induced

Although thermally induced tensile residual stresses have been known to occur in ground components, it has not been possible to predict the critical temperature at which these stresses begin to manifest themselves in the workpiece. In this paper, a model of the formation of thermally induced tensile residual stresses is proposed and a simple method of calculating the critical temperature above which tensile residual stresses occur is developed. The analysis makes use of dimensional methods to characterize the critical temperature. In addition, a formula characterizing the yield strength as a function of temperature was developed. The model was then validated using finite element techniques and some experimental data. The analysis reveals that it is possible to determine the critical temperature above which tensile residual stresses will be manifested based on readily available material properties. A case study illustrates the application of the technique.

Crack Non-Circularity and Finite Erosion Effects on the 3D SIFs of a Bauschinger Modified Pressurized Thick-Walled Cylinder

2015 ◽  
Author(s):  
Qin Ma ◽  
Cesar Levy ◽  
Mordechai Perl
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Fatigue Life ◽  
Numerical Analysis ◽  
Material Properties ◽  
Thermal Loading ◽  
Circular Crack ◽  
Finite Element Package ◽  
Pressurized Cylinder ◽  
Walled Cylinder

Our previous studies have demonstrated that the 3D SIFs of a pressurized cylinder can be greatly affected by many factors. While an autofrettage process may introduce favorable residual stresses at the bore of the cylinder, other factors such as erosions and cracks, once introduced, may greatly reduce the effectiveness of the autofrettage results. In this study, we focus on how the non-circularity of cracks affects the 3D SIFs for a cylinder that contains finite erosions while keeping other conditions and material properties unchanged. Numerical analysis was performed using ANSYS, a standard commercially available finite element package. The residual stress due to any autofrettage process was simulated using the equivalent thermal loading. A closer look was given to problems with different crack configurations and how non-circularity of cracks affects the overall fatigue life of the cylinder when combined with other factors in comparison with circular crack only configurations.

FEM-Based Simulation of Temperature in Speed Stroke Grinding with 3D Transient Moving Heat Sources

2011 ◽  
Vol 223 ◽  
pp. 733-742 ◽  
Author(s):  
Barbara Linke ◽  
Michael Duscha ◽  
Anh Tuan Vu ◽  
Fritz Klocke
Keyword(s):  
Finite Element ◽  
Material Properties ◽  
Material Removal ◽  
Structural Changes ◽  
Numerical Technique ◽  
Temperature Fields ◽  
Fe Model ◽  
Measured Temperature ◽  
Temperature Dependent ◽  
Removal Rates

The grinding process is one of the most important finishing processes to obtain high surface quality. Nowadays, grinding is also considered as a high performance process with high material removal rates. Nevertheless, to avoid thermally-induced structural changes poses a major challenge for this manufacturing technology. Until now, the Finite Element Method (FEM) has been widely applied as a proper numerical technique to predict workpiece properties in machining processes. However, actual models in grinding are limited to conventional grinding processes with simple workpiece profiles and low table speeds. In this paper, finite element simulations are expanded to 3-dimensional (3D) models with temperature-dependent material properties and heat source profiles derived from experimental results, i.e. tangential forces. Both temperature simulation and measurement were conducted for deep grinding, pendulum grinding and speed stroke grinding in the table speed range of vw= 12 m/min to 180 m/min and specific material removal rates of Q’w= 40 mm³/mms. Overall, the simulation results show a good agreement with the measured temperature and surface integrity after grinding. This research indicates that a 3D FE model with temperature dependent material properties can predict realistic temperature fields in speed stroke grinding. Therefore, the experiment and measurement costs and time can be reduced by FEM simulation.

Stability of Ring-Stiffened Tubular Members Under External Pressure

1995 ◽  
Vol 117 (2) ◽  
pp. 150-155 ◽  
Author(s):  
S. A. Karamanos ◽  
J. L. Tassoulas
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Stability Analysis ◽  
External Pressure ◽  
Nonlinear Finite Element ◽  
Steel Tubes ◽  
Deformation Plasticity ◽  
The Stability ◽  
Element Technique ◽  
Stiffened Steel

This paper presents results of a rigorous nonlinear finite element technique for the stability analysis of ring-stiffened steel tubes under external pressure. Large deformation, plasticity, as well as residual stresses and imperfections, are taken into account. Both internal and external stiffeners are simulated. A study of various parameters which affect pressure capacity is summarized, along with a comparison with available experimental data.

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