Analytical, FEA and Experimental Methods for Computing the Resilience of Tapped Thread Joints

2011 ◽  
Author(s):  
Yosef Amir ◽  
John Reif ◽  
Nicholas Konkle
Keyword(s):  
Analytical Model ◽  
Analytical Methods ◽  
Dissimilar Materials ◽  
Experimental Methods ◽  
Bolted Joint ◽  
Element Analysis ◽  
Fea Modeling ◽  
Screw Joint ◽  
Basic Parameters ◽  
Analytical Approaches

Bolted joint behavior is based on many parameters, many of which are not well known or understood. The basic parameters describing the signature behavior of the bolted joint are the fastener and clamped joint flanges’ resilience. The level of confidence in the resilience parameter defines the confidence level of further analysis performed throughout the design phase. For general cases with simple configurations of the bolt and joint members, well-known analytical methods such as VDI 2230 satisfy the purpose of bolted joint analyses. However, in practice there are cases which deviate from the idealized joint, such as complex bolted joint geometry or dissimilar materials which cannot be simplified for an analytical model. The particular case studied here is that of a screw joint or tapped thread joint (TTJ) where the analytical model is ambiguous. In addition, for TTJs that are critical to safety a high confidence in the result is desired, so finite element analysis (FEA) or experimental methods are preferred to assess the resilience of the clamped and tapped flanges. This paper presents FEA modeling as well as analytical methods for complex joints, particularly for TTJ configurations. Resilience values for FEA and analytical approaches are presented, as well as experimental results for validation.

Joining by Forming of Tubes to Sheets with Counterbored Holes

2018 ◽  
Vol 767 ◽  
pp. 421-428 ◽  
Author(s):  
Luis M. Alves ◽  
Rafael M. Afonso ◽  
Carlos M.A. Silva ◽  
Paulo A.F. Martins
Keyword(s):  
Analytical Model ◽  
Cross Section ◽  
Room Temperature ◽  
Tube Wall ◽  
Rectangular Cross Section ◽  
Dissimilar Materials ◽  
Forming Process ◽  
Element Analysis ◽  
Joining By Forming ◽  
Tube Wall Thickness

This paper presents a new joining by forming process for connecting tubes to sheets. The process consists of forming an annular flange with rectangular cross section by partial sheet-bulk of the tube wall thickness and performing the mechanical interlock by upsetting the free tube end against a flat-bottomed (counterbored) sheet hole. The presentation identifies the variables and the workability limits of the process and includes an analytical model to assist readers in the design of the new joints. The new proposed joining by forming process and the corresponding analytical model are validated by experimentation and numerical simulation using finite element analysis. The process allows connecting tubes to sheets made from dissimilar materials at room temperature, avoids the utilization of addition materials or adhesives and produces joints that are easy to disassembly at the end of live, allowing recyclability of the tubes and sheets.

scholarly journals Analytical Model of Bolted Joint Structure and Its Nonlinear Dynamic Characteristics in Transient Excitation

2016 ◽  
Vol 2016 ◽  
pp. 1-11
Author(s):  
Xin Liao ◽  
Jianrun Zhang ◽  
Xiyan Xu
Keyword(s):  
Dynamic Response ◽  
Analytical Model ◽  
Nonlinear Behavior ◽  
Nonlinear Effects ◽  
Tangential Direction ◽  
Nonlinear Stiffness ◽  
Bolted Joint ◽  
Element Analysis ◽  
Simulation Results ◽  
Cubic Stiffness

The dynamic response of crucial components often depends upon the dynamic behavior of bolted connections. As is usually the case, the accurate modeling of structures with many mechanical joints remains a challenge work. The nonlinear behavior included in assembled structures strongly depends on the interface properties. In this paper, an analytical model of the simple bolted joint beam in tangential direction is first proposed for transient excitation, based on phenomenological model. The fourth-order Runge-Kutta method is employed to calculate the transient response, where the dynamic response of the nonlinear stiffness on system is also investigated. The simulation results show that natural frequency has a certain dependence on cubic stiffness term and cubic stiffness is more suitable for modeling of nonlinear system of a wider frequency range. Thereby, a series Iwan model containing cubic stiffness term is established to describe nonlinear behaviors of bolted joint beams in shear vibration. The amplitude-frequency curves show that the influence of interaction between nonlinear stiffness and damping mechanism on dynamic response characteristics is more obvious. Finally, a new type of nonlinear model is applied into finite element analysis. The results of proposed transient excitation experiment are discussed qualitatively, indicating that nonlinear effects observed agree with the numerical simulation results.

Application of Coupled Structural Acoustic Analysis and Sensitivity Calculations to a Tire Noise Problem

2012 ◽  
Vol 40 (1) ◽  
pp. 25-41 ◽  
Author(s):  
H. M. R. Aboutorabi ◽  
L. Kung
Keyword(s):  
Performance Improvement ◽  
Acoustic Analysis ◽  
Simulation Analysis ◽  
Analysis Method ◽  
Vehicle Manufacturer ◽  
Element Analysis ◽  
Equipment Manufacturer ◽  
Tire Noise ◽  
Fea Modeling ◽  
Testing Instruments

Abstract REFERENCE: H. M. R. Aboutorabi and L. Kung, “Application of Coupled Structural Acoustic Analysis and Sensitivity Calculations to a Tire Noise Problem,” Tire Science and Technology, TSTCA, Vol. 40, No. 1, January – March 2012, pp. 25–41. ABSTRACT: Tire qualification for an original equipment (OE) program consists of several rounds of submissions by the tire manufacturer for evaluation by the vehicle manufacturer. Tires are evaluated both subjectively, where the tire performance is rated by an expert driver, and objectively, where sensors and testing instruments are used to measure the tire performance. At the end of each round of testing the evaluation results are shared and requirements for performance improvement for the next round are communicated with the tire manufacturer. As building and testing is both expensive and time consuming predictive modeling and simulation analysis that can be applied to the performance of the tire is of great interest and value. This paper presents an application of finite element analysis (FEA) modeling along with experimental verification to solve tire noise objections at certain frequencies raised by an original equipment manufacturer (OEM) account. Coupled structural-acoustic analysis method was used to find modal characteristics of the tire at the objectionable frequencies. Sensitivity calculations were then carried out to evaluate the strength of contribution from each tire component to the identified modes. Based on these findings changes to the construction were proposed and implemented that addressed the noise issue.

Evaluation of web reinforcements in prestressed concrete box girders through shear-transverse bending domains

2020 ◽  
pp. 136943322098170
Author(s):  
Michele Fabio Granata ◽  
Antonino Recupero
Keyword(s):  
Analytical Model ◽  
Prestressed Concrete ◽  
3D Analysis ◽  
Box Girders ◽  
Element Analysis ◽  
Cross Sectional ◽  
Interaction Domains ◽  
Global And Local ◽  
Resultant Forces

In concrete box girders, the amount and distribution of reinforcements in the webs have to be estimated considering the local effects due to eccentric external loads and cross-sectional distortion and not only the global effect due to the resultant forces of a longitudinal analysis: shear, torsion and bending. This work presents an analytical model that allows designers to take into account the interaction of all these effects, global and local, for the determination of the reinforcements. The model is based on the theory of stress fields and it has been compared to a 3D finite element analysis, in order to validate the interaction domains. The results show how the proposed analytical model allows an easy and reliable reinforcement evaluation, in agreement with a more refined 3D analysis but with a reduced computational burden.

DIMENSIONING OF ORTHOTROPICALLY STIFFENED CFRP SHELLS OF LARGE LAUNCH VEHICLES FOR LOAD INTRODUCTION AND STABILITY

2010 ◽  
Vol 10 (04) ◽  
pp. 601-621 ◽  
Author(s):  
ANDREAS RITTWEGER ◽  
SUSANNE CHRISTIANSON ◽  
HUBA ÖRY
Keyword(s):  
Analytical Methods ◽  
Flux Distribution ◽  
Fe Analysis ◽  
Launch Vehicles ◽  
Local Instability ◽  
Axial Loads ◽  
Ring Frame ◽  
Final Design ◽  
Shell Equations ◽  
Analytical Approaches

The dimensioning of an orthotropically stiffened cylindrical CFRP shell subjected to the introduction of concentrated axial loads using rapid analytical methods is presented. For stress calculation the shell equations are simplified by applying the semibending theory and integrated by employing the transfer matrix method. Analytical approaches are used for stability verification. The dimensioning considers required constraints in the force flux distribution, strength of the laminate, general instability, panel instability (from ring frame to ring frame) and local instability. The rapid analytical methods allow mass optimization. The final design is confirmed by detailed FE analysis. A comparison of the FE analysis with the analytical results is shown.

Detailed Stress Analysis of a Spherical Acrylic Submersible by 3-D Finite Element Modeling

1999 ◽  
Author(s):  
Partha S. Das
Keyword(s):  
Finite Element ◽  
Numerical Modeling ◽  
Dissimilar Materials ◽  
Analysis Model ◽  
Element Analysis ◽  
Finite Element Analysis Model ◽  
New Model ◽  
Ocean Exploration ◽  
Near Future ◽  
First Time

Abstract Harbor Branch Oceanographic Institution (HBOI) designed, built and has operated two JOHNSON-SEA-LINK (JSL) manned submersibles for the past 25 years. The JSL submersibles each incorporate a 66–68 in. (1.6764–1.7272 m) OD, 4–5.25 in. (0.1016–0.13335 m) thick acrylic two-man sphere as a Pressure Vessel for Human Occupancy (PVHO). This type of spherical acrylic sphere or submersible was first introduced in around 1970 and is known as Naval Experimental Manned Observatory (NEMO) submersibles. As the demand increases for ocean exploration to 3000 ft. (914.4 m) depth to collect samples, to study the ocean surfaces, the problem of developing cracks at the interface of these manned acrylic submersibles following few hundred dives have become a common phenomena. This has drawn considerable attentions for reinvestigation of the spherical acrylic submersible in order to overcome this crack generation problem at the interface. Therefore, a new full-scale 3-D nonlinear FEA (Finite Element Analysis) model, similar to the spherical acrylic submersible that HBOI uses for ocean exploration, has been developed for the first time in order to simulate the structural behavior at the interface and throughout the sphere, for better understanding of the mechanical behavior. Variation of the stiffness between dissimilar materials at the interface, lower nylon gasket thickness, over designed aluminum hatch are seemed to be few of the causes for higher stresses within acrylic sphere at the nylon gasket/acrylic interface. Following the basic understanding of the stresses and relative displacements at the interface and within different parts of the submersible, various models have been developed on the basis of different shapes and thickness of nylon gaskets, openings of the acrylic sphere, hatch geometry and its materials, specifically to study their effect on the overall performance of the acrylic submersible. Finally, the new model for acrylic submersible has been developed by redesigning the top aluminum hatch and hatch ring, the sphere openings at both top and bottom, as well as the nylon gasket inserts. Altogether this new design indicates a significant improvement over the existing spherical acrylic submersible by reducing the stresses at the top gasket/acrylic interface considerably. Redesigning of the bottom penetrator plate, at present, is underway. In this paper, results from numerical modeling only are reported in details. Correlation between experimental-numerical modeling results for the new model will be reported in the near future.

scholarly journals Nonlinear Axial Stiffness Characteristics of Axisymmetric Bolted Joints

1990 ◽  
Vol 112 (3) ◽  
pp. 442-449 ◽  
Author(s):  
I. R. Grosse ◽  
L. D. Mitchell
Keyword(s):  
Finite Element ◽  
Linear Theory ◽  
Design Theory ◽  
Joint Stiffness ◽  
Bolted Joints ◽  
Axial Stiffness ◽  
Outer Diameter ◽  
Bolted Joint ◽  
Element Analysis ◽  
Stiffness Characteristics

A critical assessment of the current design theory for bolted joints which is based on a linear, one-dimensional stiffness analysis is presented. A detailed nonlinear finite element analysis of a bolted joint conforming to ANSI standards was performed. The finite element results revealed that the joint stiffness is highly dependent on the magnitude of the applied load. The joint stiffness changes continuously from extremely high for small applied loads to the bolt stiffness during large applied loads, contrary to the constant joint stiffness of the linear theory. The linear theory is shown to be inadequate in characterizing the joint stiffness. The significance of the results in terms of the failure of bolted joints is discussed. A number of sensitivity studies were carried out to assess the effect of various parameters on the axial joint stiffness. The results revealed that bending and rotation of the joint members, interfacial friction, and the bolt/nut threading significantly influence the axial stiffness characteristics of the bolted joint. The two-dimensional, axisymmetric finite element model includes bilinear gap elements to model the interfaces. Special orthotropic elements were used to model the bolt/nut thread interaction. A free-body-diagram approach was taken by applying loads to the outer diameter of the joint model which correspond to internal, uniformly distributed line-shear and line-moment loads in the joint. A number of convergence studies were performed to validate the solution.

scholarly journals Tetraconatan phylogeny with special focus on Malacostraca and Branchiopoda: highlighting the strength of taxon-specific matrices in phylogenomics

2018 ◽  
Vol 285 (1885) ◽  
pp. 20181524 ◽  
Author(s):  
Martin Schwentner ◽  
Stefan Richter ◽  
D. Christopher Rogers ◽  
Gonzalo Giribet
Keyword(s):  
Amino Acid ◽  
Analytical Methods ◽  
Special Focus ◽  
Evolutionary Models ◽  
Phylogenomic Analyses ◽  
New Generation ◽  
Analytical Approaches ◽  
Internal Relationships ◽  
Complete Matrix ◽  
Phylogenomic Study

Understanding the evolution of Tetraconata or Pancrustacea—the clade that includes crustaceans and insects—requires a well-resolved hypothesis regarding the relationships within and among its constituent taxa. Here, we assembled a taxon-rich phylogenomic dataset focusing on crustacean lineages based solely on genomes and new-generation Illumina-generated transcriptomes, including 89 representatives of Tetraconata. This constitutes, to our knowledge, the first phylogenomic study specifically addressing internal relationships of Malacostraca (with 26 species included) and Branchiopoda (36 species). Seven matrices comprising 81–684 orthogroups and 17 690–242 530 amino acid positions were assembled and analysed under five different analytical approaches. To maximize gene occupancy and to improve resolution, taxon-specific matrices were designed for Malacostraca and Branchiopoda. Key tetraconatan taxa (i.e. Oligostraca, Multicrustacea, Branchiopoda, Malacostraca, Thecostraca, Copepoda and Hexapoda) were monophyletic and well supported. Within Branchiopoda, Phyllopoda, Diplostraca, Cladoceromorpha and Cladocera were monophyletic. Within Malacostraca, the clades Eumalacostraca, Decapoda and Reptantia were well supported. Recovery of Caridoida or Peracarida was highly dependent on the analysis for the complete matrix, but it was consistently monophyletic in the malacostracan-specific matrices. From such examples, we demonstrate that taxon-specific matrices and particular evolutionary models and analytical methods, namely CAT-GTR and Dayhoff recoding, outperform other approaches in resolving certain recalcitrant nodes in phylogenomic analyses.

Role of Out-of-Plane Coefficient of Thermal Expansion in Electronic Packaging Modeling

1999 ◽  
Vol 122 (2) ◽  
pp. 121-127 ◽  
Author(s):  
Manjula N. Variyam ◽  
Weidong Xie ◽  
Suresh K. Sitaraman
Keyword(s):  
Thermal Expansion ◽  
Electronic Packaging ◽  
Thermal Loading ◽  
Coefficient Of Thermal Expansion ◽  
Plane Deformation ◽  
Three Dimensional ◽  
Dissimilar Materials ◽  
3D Models ◽  
Material Behavior ◽  
Element Analysis

Components in electronic packaging structures are of different dimensions and are made of dissimilar materials that typically have time, temperature, and direction-dependent thermo-mechanical properties. Due to the complexity in geometry, material behavior, and thermal loading patterns, finite-element analysis (FEA) is often used to study the thermo-mechanical behavior of electronic packaging structures. For computational reasons, researchers often use two-dimensional (2D) models instead of three-dimensional (3D) models. Although 2D models are computationally efficient, they could provide misleading results, particularly under thermal loading. The focus of this paper is to compare the results from various 2D, 3D, and generalized plane-deformation strip models and recommend a suitable modeling procedure. Particular emphasis is placed to understand how the third-direction coefficient of thermal expansion (CTE) influences the warpage and the stress results predicted by 2D models under thermal loading. It is seen that the generalized plane-deformation strip models are the best compromise between the 2D and 3D models. Suitable analytical formulations have also been developed to corroborate the findings from the study. [S1043-7398(00)01402-X]

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