An Experimental and Finite Element Study of Thermal Fatigue Fracture of PbSn Solder Joints

1993 ◽  
Vol 115 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Yi-Hsin Pao ◽  
Ratan Govila ◽  
Scott Badgley ◽  
Edward Jih
Keyword(s):  
Finite Element ◽  
Solder Alloy ◽  
Thermal Fatigue ◽  
Fracture Behavior ◽  
Hysteresis Loops ◽  
Element Model ◽  
Thermal Cycles ◽  
Stress Strain ◽  
Secondary Cracks ◽  
Pbsn Solder

A solder joint specimen has been designed to determine the stress/strain hysteresis response and fracture behavior of 90 percent wtPb/10 percent wtSn solder alloy. The specimen consists of an Al2O3 beam and an Al 2024-T4 beam bonded together at the ends with solder. The specimen is subjected to thermal cycling to failure between 40°C to 140°C with a 10°C/min ramp rate and 10-minute hold times. Stress/strain hysteresis loops were experimentally determined as a function of thermal cycles. A method based on the stress relaxation data at hold times has been developed to determine the steady state creep parameters of the solder. A constitutive equation for the solder alloy based on elastic and creep deformation has been formulated and implemented in a finite element code, ABAQUS. Good agreement was obtained between the finite element model and the experimental results. In the thermal fatigue test, crack length versus number of thermal cycles was measured for two different shear strain ranges, and the fracture surface was examined with SEM. The SEM results show a combined transgranular and intergranular fracture. In addition, a significant amount of secondary cracks and voids were generated during thermal fatigue which led to material weakening. A thermal fatigue model based on the C* integral, the measured stress history, and creep properties was employed to model the fracture behavior.

КОНСТРУКТИВНО-ТЕХНОЛОГІЧНІ ОСОБЛИВОСТІ ХВОСТО-ВИХ БАЛОК СІТЧАСТОГО ТИПУ З ПОЛІМЕРНИХ КОМПО-ЗИЦІЙНИХ МАТЕРІАЛІВ ВЕРТОЛЬОТІВ ТРАНСПОРТНОЇ КАТЕГОРІЇ

2020 ◽  
pp. 15-30
Author(s):  
А. Г. Гребеников ◽  
И. В. Малков ◽  
В. А. Урбанович ◽  
Н. И. Москаленко ◽  
Д. С. Колодийчик
Keyword(s):  
Finite Element ◽  
Strain State ◽  
Layer Structure ◽  
Metal Structure ◽  
Element Model ◽  
Stress Strain ◽  
Element Analysis ◽  
Mesh Structure ◽  
Stress Strain State ◽  
Mesh Structures

The analysis of the design and technological features of the tail boom (ТB) of a helicopter made of polymer composite materials (PCM) is carried out.Three structural and technological concepts are distinguished - semi-monocoque (reinforced metal structure), monocoque (three-layer structure) and mesh-type structure. The high weight and economic efficiency of mesh structures is shown, which allows them to be used in aerospace engineering. The physicomechanical characteristics of the network structures are estimated and their uniqueness is shown. The use of mesh structures can reduce the weight of the product by a factor of two or more.The stress-strain state (SSS) of the proposed tail boom design is determined. The analysis of methods for calculating the characteristics of the total SSS of conical mesh shells is carried out. The design of the tail boom is presented, the design diagram of the tail boom of the transport category rotorcraft is developed. A finite element model was created using the Siemens NX 7.5 system. The calculation of the stress-strain state (SSS) of the HC of the helicopter was carried out on the basis of the developed structural scheme using the Advanced Simulation module of the Siemens NX 7.5 system. The main zones of probable fatigue failure of tail booms are determined. Finite Element Analysis (FEA) provides a theoretical basis for design decisions.Shown is the effect of the type of technological process selected for the production of the tail boom on the strength of the HB structure. The stability of the characteristics of the PCM tail boom largely depends on the extent to which its design is suitable for the use of mechanized and automated production processes.A method for the manufacture of a helicopter tail boom from PCM by the automated winding method is proposed. A variant of computer modeling of the tail boom of a mesh structure made of PCM is shown.The automated winding technology can be recommended for implementation in the design of the composite tail boom of the Mi-2 and Mi-8 helicopters.

Delamination in the scoring and folding of paperboard

TAPPI Journal ◽  
2012 ◽  
Vol 11 (1) ◽  
pp. 61-66 ◽  
Author(s):  
DOEUNG D. CHOI ◽  
SERGIY A. LAVRYKOV ◽  
BANDARU V. RAMARAO
Keyword(s):  
Finite Element ◽  
Plane Deformation ◽  
Strain Analysis ◽  
Local Strain ◽  
Uniaxial Stress ◽  
Material Model ◽  
Element Model ◽  
Plastic Behavior ◽  
Stress Strain ◽  
Strain Fields

Delamination between layers occurs during the creasing and subsequent folding of paperboard. Delamination is necessary to provide some stiffness properties, but excessive or uncontrolled delamination can weaken the fold, and therefore needs to be controlled. An understanding of the mechanics of delamination is predicated upon the availability of reliable and properly calibrated simulation tools to predict experimental observations. This paper describes a finite element simulation of paper mechanics applied to the scoring and folding of multi-ply carton board. Our goal was to provide an understanding of the mechanics of these operations and the proper models of elastic and plastic behavior of the material that enable us to simulate the deformation and delamination behavior. Our material model accounted for plasticity and sheet anisotropy in the in-plane and z-direction (ZD) dimensions. We used different ZD stress-strain curves during loading and unloading. Material parameters for in-plane deformation were obtained by fitting uniaxial stress-strain data to Ramberg-Osgood plasticity models and the ZD deformation was modeled using a modified power law. Two-dimensional strain fields resulting from loading board typical of a scoring operation were calculated. The strain field was symmetric in the initial stages, but increasing deformation led to asymmetry and heterogeneity. These regions were precursors to delamination and failure. Delamination of the layers occurred in regions of significant shear strain and resulted primarily from the development of large plastic strains. The model predictions were confirmed by experimental observation of the local strain fields using visual microscopy and linear image strain analysis. The finite element model predicted sheet delamination matching the patterns and effects that were observed in experiments.

scholarly journals On the issue of dynamic loading of supporting structures of special wheeled chassis

2019 ◽  
pp. 73-83
Author(s):  
V. I. Tarichko ◽  
P. I. Shalupina
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Dynamic Loading ◽  
Strain State ◽  
Element Model ◽  
Stress Strain ◽  
Full Size ◽  
Equivalent Stresses ◽  
Stress Strain State ◽  
Supporting Structures

The paper focuses on a method for assessing the dynamic loading of the frame of a special wheeled chassis when it moves on roads of various categories. Based on the developed finite element model of the frame, we obtained and analyzed full-size patterns of the stress-strain state of the frame and oscillograms of equivalent stresses in the most loaded zones of the frame.

Improved Correlation of Measured and Predicted Hysteresis Loops in a Multiaxial Fretting Fatigue Test Rig for Spline Couplings

2007 ◽  
Vol 7-8 ◽  
pp. 37-42
Author(s):  
D. Houghton ◽  
P.M. Wavish ◽  
Edward J. Williams ◽  
Sean B. Leen
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Fatigue Test ◽  
Hysteresis Loops ◽  
Element Model ◽  
Fretting Fatigue ◽  
Global Model ◽  
Test Rig ◽  
Force Displacement

This paper investigates the comparison of the measured and predicted force-displacement loops of a multiaxial representative fretting fatigue test rig for aeroengine spline couplings. A local finite element model of the fretting specimen and the fretting bridge is outlined. A more extensive model of the fretting test rig is then introduced. This global model also includes the loading structures. The model captures the compliance of the fretting test rig and improves the correlation of the observed hysteresis. This method allows the slip amplitude at the contacts to be quantified.

scholarly journals Field Variable Associations With Scratch Orientation Dependence of UHMWPE Wear: A Finite Element Analysis

2008 ◽  
Vol 130 (6) ◽  
Author(s):  
Matthew C. Paul ◽  
Liam P. Glennon ◽  
Thomas E. Baer ◽  
Thomas D. Brown
Keyword(s):  
Finite Element ◽  
Computational Models ◽  
Three Dimensional ◽  
Element Model ◽  
Field Variable ◽  
Orientation Dependence ◽  
Normal Strain ◽  
Stress Strain ◽  
Element Analysis ◽  
Local Direction

Scratches on the metal bearing surface of metal-on-polyethylene total joint replacements have been found to appreciably accelerate abrasive/adhesive wear of polyethylene, and constitute a source of the considerable variability of wear rate seen within clinical cohorts. Scratch orientation with respect to the local direction of relative surface sliding is presumably a factor affecting instantaneous debris liberation during articulation. A three-dimensional local finite element model was developed, of orientation-specific polyethylene articulation with a scratched metal counterface, to explore continuum-level stress/strain parameters potentially correlating with the orientation dependence of scratch wear in a corresponding physical experiment. Computed maximum stress values exceeded the yield strength of ultra-high molecular weight polyethylene (UHMWPE) for all scratch orientations but did not vary appreciably among scratch orientations. Two continuum-level parameters judged most consistent overall with the direction dependence of experimental wear were (1) cumulative compressive total normal strain in the direction of loading, and (2) maximum instantaneous compressive total normal strain transverse to the sliding direction. Such stress/strain metrics could be useful in global computational models of wear acceleration, as surrogates to incorporate anisotropy of local metal surface roughening.

Simulation of Fracture Behavior in the Microstructure of Ceramic Tool Materials

2012 ◽  
Vol 457-458 ◽  
pp. 89-92
Author(s):  
Ting Ting Zhou ◽  
Chuan Zhen Huang ◽  
Han Lian Liu ◽  
Jun Wang ◽  
Bin Zou ◽  
...  
Keyword(s):  
Finite Element ◽  
Grain Boundary ◽  
Fracture Resistance ◽  
Fracture Behavior ◽  
Single Phase ◽  
Voronoi Tessellation ◽  
Element Model ◽  
Cohesive Element ◽  
Ceramic Tool ◽  
Tool Materials

In the paper, the Voronoi tessellation model is used to represent the microstructure of ceramic tool materials. And a finite element model based on cohesive element method has been developed to investigate the fracture behavior of the microstructure. The influences of mesh densities and cohesive parameters on the cracking patterns have been discussed. It is found that the enhancement of the grain boundary strength is beneficial for raising the fracture resistance of single-phase ceramic tool materials.

scholarly journals An experimental study of the stress-strain state of the engine piston skirt on the engineless stand

2019 ◽  
Vol 20 (4) ◽  
pp. 285-292
Author(s):  
Sergei V. Smirnov ◽  
Vladimir V. Kopylov ◽  
Alexander R. Makarov ◽  
Alexander A. Vorobyev ◽  
Kirill V. Shkarin
Keyword(s):  
Finite Element ◽  
Strain State ◽  
Combustion Engine ◽  
Experimental Studies ◽  
Element Model ◽  
Design Development ◽  
Stress Strain ◽  
Piston Skirt ◽  
Stress Strain State ◽  
The Cost

The article describes the features developed by the authors of the profiling method of the piston skirt, provides the main parameters that affect the lubrication conditions of the piston skirt and the magnitude of mechanical losses. In computational studies, the basic formulas are given for determining the thickness of the oil layer in a piston skirt - cylinder sleeve conjunction to assess the nature of friction. To determine the deformations, the finite element method is used on the spatial model of the piston. To verify the finite element model, a stand for experimental studies was developed. The article describes the developed stand, the methodology and results of experimental studies of the stress-strain state of the two-piece piston skirt obtained at this stand and a comparative analysis of the results of the calculated and experimental studies of the stress-strain state of the two-piece piston skirt of a diesel engine. The research results showed that the developed stand can be used to verify mathematical models for calculating the stress-strain state of the piston skirt in the pilot production of internal combustion engine pistons to accelerate and reduce the cost of the piston design development process, as well as the results of experimental studies obtained at the stand, can be used as initial data for the developed mathematical model of the dynamics of the movement of the piston and the profiling of the piston skirt.

scholarly journals STRESS-STRAIN STATE OF FRAME STRUCTURES AT THE DIFFERENT SNOW PRESSURE

2019 ◽  
Vol 7 (2) ◽  
pp. 5-9
Author(s):  
Галина Кравченко ◽  
Galina Kravchenko ◽  
Елена Труфанова ◽  
Elena Trufanova ◽  
Денис Суслопаров ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Strain State ◽  
Element Model ◽  
Frame Structures ◽  
Stress Strain ◽  
Snow Load ◽  
Stress Strain State ◽  
Snow Pressure ◽  
Snow Loading

The multi-variant loading of the large-span unique steel covering of the stadium under snow load is considered. The spatial finite element model is developed using LIRA software. The analysis of the existing schemes application of snow loading is carried out according to the codes. Four snow load cases on the stadium's covering are assumed for analysis. The analysis of the stress-strain state of the stadium structures, the selection and verification of sections of the steel covering are performed. The results show that it is necessary to simulate behaviour of a structure under all possible load cases.

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