Finite element evaluation of elasto-plastic accommodation energies during solid state transformations: Coherent, spherical precipitate in finite matrix

1996 ◽  
Vol 44 (2) ◽  
pp. 437-444 ◽  
Author(s):  
Subhajyoti Sen ◽  
R. Balasubramaniam ◽  
Raju Sethuraman
Keyword(s):  
Finite Element ◽  
Solid State ◽  
Finite Matrix ◽  
Spherical Precipitate

Simple Benchmark Problems for Finite Element Weld Residual Stress Simulation

2013 ◽  
Author(s):  
Mike C. Smith ◽  
Steve Bate ◽  
P. John Bouchard
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Phase Transformation ◽  
Solid State ◽  
Residual Stresses ◽  
Benchmark Problems ◽  
Transient Temperature ◽  
Beam Specimen ◽  
Weld Residual Stress ◽  
Solid State Phase Transformation

Finite element methods are used increasingly to predict weld residual stresses. This is a relatively complex use of the finite element method, and it is important that its practitioners are able to demonstrate their ability to produce accurate predictions. Extensively characterised benchmark problems are a vital tool in achieving this. However, existing benchmarks are relatively complex and not suitable for analysis by novice weld modellers. This paper describes two benchmarks based upon a simple beam specimen with a single autogenous weld bead laid along its top edge. This geometry may be analysed using either 3D or 2D FE models and employing either block-dumped or moving heat source techniques. The first, simpler, benchmark is manufactured from AISI 316 steel, which does not undergo solid state phase transformation, while the second, more complex, benchmark is manufactured from SA508 Cl 3 steel, which undergoes solid state phase transformation during welding. A number of such beams were manufactured using an automated TIG process, and instrumented with thermocouples and strain gauges to record the transient temperature and strain response during welding. The resulting residual stresses were measured using diverse techniques, and showed markedly different distributions in the austenitic and ferritic beams. The paper presents the information necessary to perform and validate finite element weld residual stress simulations in both the simple austenitic beam and the more complex ferritic beam, and provides performance measures for the austenitic beam problem.

Sensitivity Analysis on Solder Joint Fatigue Life of Solid State Drives by Finite Element Method and Monte Carlo Simulation

2017 ◽  
Author(s):  
Y. J. Cho ◽  
J. W. Jang ◽  
G. H. Jang
Keyword(s):  
Finite Element Method ◽  
Monte Carlo Simulation ◽  
Finite Element ◽  
Monte Carlo ◽  
Fatigue Life ◽  
Solid State ◽  
Thermal Cycling ◽  
Solder Ball ◽  
Solid State Drives ◽  
Element Method

We proposed a method to estimate a distribution of fatigue life of solid state drives (SSDs) due to thermal cycling excitation by using finite element method and Monte Carlo simulation. In the developed finite element model, we utilized the Anand model to represent the viscoplastic behavior of the solder balls, and we also utilized the Prony series to represent the viscoelastic behavior of the polymer material in underfill. We determined a fatigue life of the SSD by using the Morrow’s energy-based fatigue model. Finally, we determined a distribution of fatigue life considering the manufacturing tolerance of the design variables and the variation of material properties in the Monte Carlo simulation. Finite element analysis shows that the outermost solder ball at the corner of dynamic random access memory was the most vulnerable component under the thermal cycling excitation. We also show that temperature profile and diameter of solder ball affect dominantly the fatigue life of the SSD.

scholarly journals Experimental Analysis of Self Piercing Riveted Joint

2019 ◽  
pp. 303-310
Author(s):  
R. T. Kolhe ◽  
V. L. Kadlag
Keyword(s):  
Finite Element ◽  
Solid State ◽  
Adhesive Bonding ◽  
Oil And Gas ◽  
Tensile Force ◽  
Statistical Design ◽  
Element Model ◽  
Tensile Tests ◽  
State Process

Joining is an important process in a number of industries, such as aerospace, automotive, oil, and gas. Many products cannot be fabricated as a single piece, so components are fabricated first and assembled later. Joining technology can be classified as a liquid-solid-state process and mechanical means. Liquid-solid-state joining includes welding, brazing, soldering, and adhesive bonding. Mechanical joining includes fasteners, bolts, nuts, and rivets. Metal joining is a process that uses heat to melt or heat metal just below the melting temperature. The main principle is a shear condition of material. In case of shear test of conventional riveting joints, their strength is determined by the mechanical properties of the fastener material is high. Hence, it is expedient to have more insight on the fracture mechanism of various joints during tensile tests. This paper discusses the strength of self piercing rivets of sheet materials that is aluminum alloy, and their arrangements. This thesis presents a study of the effect of controllable self piercing rivet parameters, mainly tensile force, rivet length, rivet diameter tolerance, hole countersunk depth and hole diameter tolerance, on the quality of formed rivet. The quality of a formed rivet is determined by the geometry of its head formation and the extent to which the hole is filled. The study determines. The study is performed using finite element simulation of the riveting process. Theoretical relations between tensile force and formed rivet geometry derived in this study is used to validate the finite element model. Statistical design of experiment is employed to analyze the simulation data of riveting and determine the effect of individual factors, their interactions and relationship with the quality of formed self piercing rivet. The results demonstrate that the correct formation of rivet head geometry depends upon all the factors studied.

Neutronic and Thermal-Mechanical Coupling Schemes for Heat Pipe Cooled Reactor Designs

2020 ◽  
Author(s):  
Yugao Ma ◽  
Minyun Liu ◽  
Wenbin Han ◽  
Biheng Xie ◽  
Xiaoming Chai ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Monte Carlo ◽  
Solid State ◽  
Heat Pipe ◽  
Mechanical Response ◽  
Thermal Analyses ◽  
Monte Carlo Program ◽  
Relaxation Methods ◽  
Water Reactors

Abstract Space fission power systems can enable ambitious solar-system and deep-space science missions. The heat pipe cooled reactor is one of the most potential candidates for near-term space power supply, featured with safety, simplicity, reliability, and modularity. Heat pipe cooled reactors are solid-state and high temperature (up to 1500 K) reactors, where the thermal expansion is remarkable and the mechanical response significantly influences the neutronics and thermal analyses. Due to the considerable difference between heat pipe cooled reactors and traditional water reactors in the structure and design concept, the coupling solutions for light water reactors cannot be directly applied to heat pipe cooled reactor analyses. Therefore, new coupling framework and program need to consider the coupling effects among neutronics, heat transfer as well as mechanics. Based on the Monte Carlo program RMC and commercial finite element program ANSYS Mechanical APDL, this work introduces the three coupling fields of neutronics (N), thermal (T), and mechanics (M) for heat pipe cooled reactors. The neutronic and thermal-mechanical (N/T-M) coupling strategy is developed theoretically, focusing on the formulation of the nonlinear problem, iteration schemes, and relaxation methods. Besides, the finite element method and the Monte Carlo program use different meshes and geometry construction methods. The spatial mapping and geometry reconstruction are also essential for the N/T-M coupling, which is discussed and established in detail. Furthermore, the N/T-M coupling methods are applied to the preliminary self-designed 10 kWe space heat pipe cooled reactor. Coupling shows that the thermal-mechanical feedback in the solid-state reactor has negative reactivity feedback (−2007 pcm) while it has a deterioration in heat transfer due to the expansion in the gas gap.

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