Stress Singularity Effect on Beam Flanges in Moment Connections

2005 ◽  
Vol 8 (2) ◽  
pp. 143-156 ◽  
Author(s):  
J. Kent Hsiao ◽  
Janice J. Chambers ◽  
William J. Schultz
Keyword(s):  
Finite Element ◽  
Steel Plate ◽  
Stress Singularity ◽  
Northridge Earthquake ◽  
Finite Element Analyses ◽  
Stress Singularities ◽  
Moment Connections ◽  
Nonlinear Static ◽  
Ductility Capacity ◽  
Free Edges

The ductility capacity of the directly welded flange connection was found to be insufficient after the 1994 Northridge earthquake. The Enlarged End Section (EES) connection which considers the stress singularity effect on beam flanges can be utilized as a means to improve the performance of welded moment connections. The corner of a steel plate contains stress singularities (unbounded stresses) when the corner is bounded by free-free edges and when the angle of the corner is larger than 180°. Also, the corner of a steel plate contains stress singularities when the corner is bounded by fixed-free edges and when the angle of the corner is larger than 61.3°. Nonlinear static finite element analyses of two types of beam-to-column moment connections were conducted. These two types of connections are (1) the constant-beam-section connection, and (2) the Enlarged End Section connection. The result of the finite element analyses shows that the Enlarged End Section connection exhibits much higher strength and ductility capacities.

Finite Element Analysis of Stress Singularities in Attached Flip Chip Packages

2000 ◽  
Vol 122 (4) ◽  
pp. 301-305 ◽  
Author(s):  
A. Q. Xu ◽  
H. F. Nied
Keyword(s):  
Contact Angle ◽  
Finite Element ◽  
Glass Fiber ◽  
Flip Chip ◽  
Three Dimensional ◽  
Stress Singularity ◽  
Local Stress ◽  
Stress Singularities ◽  
Element Analysis ◽  
Three Dimensional Finite Element

Cracking and delamination at the interfaces of different materials in plastic IC packages is a well-known failure mechanism. The investigation of local stress behavior, including characterization of stress singularities, is an important problem in predicting and preventing crack initiation and propagation. In this study, a three-dimensional finite element procedure is used to compute the strength of stress singularities at various three-dimensional corners in a typical Flip-Chip assembled Chip-on-Board (FCOB) package. It is found that the stress singularities at the three-dimensional corners are always more severe than those at the corresponding two-dimensional edges, which suggests that they are more likely to be the potential delamination sites. Furthermore, it is demonstrated that the stress singularity at the upper silicon die/epoxy fillet edge can be completely eliminated by an appropriate choice in geometry. A weak stress singularity at the FR4 board/epoxy edge is shown to exist, with a stronger singularity located at the internal die/epoxy corner. The influence of the epoxy contact angle and the FR4 glass fiber orientation on stress state is also investigated. A general result is that the strength of the stress singularity increases with increased epoxy contact angle. In addition, it is shown that the stress singularity effect can be minimized by choosing an appropriate orientation between the glass fiber in the FR4 board and the silicon die. Based on these results, several guidelines for minimizing edge stresses in IC packages are presented. [S1043-7398(00)00904-X]

REINFORCEMENT OF AGEING SHIP STRUCTURES

2021 ◽  
Vol 160 (A3) ◽  
Author(s):  
D Chichì ◽  
Y Garbatov
Keyword(s):  
Monte Carlo Simulation ◽  
Finite Element ◽  
Ultimate Strength ◽  
Steel Plate ◽  
Plate Thickness ◽  
Compressive Load ◽  
Finite Element Models ◽  
Uniform Corrosion ◽  
Finite Element Analyses ◽  
Longitudinal Stiffeners

The objective of the present study is to investigate the possibility to recover the ultimate strength of a rectangular steel plate with a manhole shape opening subjected to a uniaxial compressive load and non-uniform corrosion degradation reinforced by additional stiffeners. Finite element analyses have been carried out to verify the possible design solutions. A total of four finite element models are generated, including 63 sub-structured models. The non-uniform corrosion has been generated by the Monte Carlo simulation. The reinforcement process covers three scenarios that include mounting of two longitudinal stiffeners, two longitudinal and two transverse stiffeners and the flange on the opening. The positioning of the stiffeners has also been studied. A total of 10 cases has been selected and tested for the numerical experiment. Three different assessments have been performed to evaluate the ultimate strength, weight and cost. Two additional studies on the effect of the plate thickness and slenderness have been also carried out.

Reinforcement of Ageing Ship Structures

2018 ◽  
Vol Vol 160 (A3) ◽  
Author(s):  
D Chichì ◽  
Y Garbatov
Keyword(s):  
Monte Carlo Simulation ◽  
Finite Element ◽  
Ultimate Strength ◽  
Steel Plate ◽  
Plate Thickness ◽  
Compressive Load ◽  
Finite Element Models ◽  
Uniform Corrosion ◽  
Finite Element Analyses ◽  
Longitudinal Stiffeners

The objective of the present study is to investigate the possibility to recover the ultimate strength of a rectangular steel plate with a manhole shape opening subjected to a uniaxial compressive load and non-uniform corrosion degradation reinforced by additional stiffeners. Finite element analyses have been carried out to verify the possible design solutions. A total of four finite element models are generated, including 63 sub-structured models. The non-uniform corrosion has been generated by the Monte Carlo simulation. The reinforcement process covers three scenarios that include mounting of two longitudinal stiffeners, two longitudinal and two transverse stiffeners and the flange on the opening. The positioning of the stiffeners has also been studied. A total of 10 cases has been selected and tested for the numerical experiment. Three different assessments have been performed to evaluate the ultimate strength, weight and cost. Two additional studies on the effect of the plate thickness and slenderness have been also carried out.

Stress singularities at the free surface of an axisymmetric two-material creep test specimen

1997 ◽  
Vol 32 (2) ◽  
pp. 107-117 ◽  
Author(s):  
T H Hyde ◽  
W Sun
Keyword(s):  
Free Surface ◽  
Steady State ◽  
Creep Test ◽  
Test Specimen ◽  
Stress Singularity ◽  
Finite Element Analyses ◽  
Stress Singularities ◽  
Material Creep ◽  
Power Law Creep ◽  
Relative Creep

The nature of the stress singularity that occurs at the surface of an axisymmetric, two-material creep test specimen has been investigated. Steady state finite element analyses were obtained for this purpose, using Norton's power law creep equations having the same stress exponent for each material. The strength of the singularity was found to be strongly dependent upon the relative creep strengths of the two materials, but was surprisingly insensitive to the relative dimensions of the two materials. The implications of the results for practical situations are discussed.

Design of flexure revolute joint based on compliance and stiffness ellipsoids

2021 ◽  
pp. 095441002110169
Author(s):  
Jing Zhang ◽  
Hong-wei Guo ◽  
Juan Wu ◽  
Zi-ming Kou ◽  
Anders Eriksson
Keyword(s):  
Finite Element ◽  
Single Point ◽  
Synthesis Method ◽  
Nonlinear Finite Element ◽  
Finite Element Analyses ◽  
Rotational Stiffness ◽  
Rotational Angle ◽  
Parameterized Model ◽  
Flexure Joints ◽  
Translational Stiffness

In view of the problems of low accuracy, small rotational angle, and large impact caused by flexure joints during the deployment process, an integrated flexure revolute (FR) joint for folding mechanisms was designed. The design was based on the method of compliance and stiffness ellipsoids, using a compliant dyad building block as its flexible unit. Using the single-point synthesis method, the parameterized model of the flexible unit was established to achieve a reasonable allocation of flexibility in different directions. Based on the single-parameter error analysis, two error models were established to evaluate the designed flexure joint. The rotational stiffness, the translational stiffness, and the maximum rotational angle of the joints were analyzed by nonlinear finite element analyses. The rotational angle of one joint can reach 25.5° in one direction. The rotational angle of the series FR joint can achieve 50° in one direction. Experiments on single and series flexure joints were carried out to verify the correctness of the design and analysis of the flexure joint.

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