Structural Abstraction in Snap-fit Analysis

2000 ◽  
Vol 122 (4) ◽  
pp. 395-402 ◽  
Author(s):  
Gaurav Suri ◽  
Anthony F. Luscher
Keyword(s):  
Finite Element ◽  
Accurate Estimation ◽  
Test Cases ◽  
Finite Element Models ◽  
Feature Models ◽  
Engineering Activity ◽  
End Conditions ◽  
Unrealistic Assumption ◽  
Fixed End ◽  
Plastic Parts

Snap-fit design has always been more of an art instead of an engineering activity. Research in this area focuses on generating finite element models for predicting the performance of snap-fit features. Such research typically uses fixed-end conditions at the base of the snap-fit feature. Often this is an unrealistic assumption, because snap-fits are usually molded on plastic parts with significant flexibility. The performance of snap-fits can be significantly influenced by this additional flexibility. To predict this performance of snap-fits it often becomes necessary to analyze the entire part, which can be a costly and time consuming process. There is no general methodology in the open literature to incorporate base-part flexibility into the design of snap-fit features. Existing work in this area is inaccurate and limited to certain base-part and snap-fit topologies. This paper proposes a new methodology called structural abstraction for incorporating base-part flexibility into snap-fit feature models. This methodology abstracts base-parts as spring elements with various stiffnesses. The underlying theory and the relevant relationships are developed and the approach is validated using several test cases. Independence of the approach to both base-part and snap-fit topologies is established and shown to be a major advantage of this technique. Use of this methodology will improve snap-fit analysis and give a more accurate estimation of retention strength. It is shown that in certain cases the improvement in accuracy over conventional finite element models of snap-fits can be as high as 70 percent. [S1050-0472(00)02504-6]

Structural Abstraction in Snap-Fit Analysis

1999 ◽  
Author(s):  
Gaurav Suri ◽  
Anthony F. Luscher
Keyword(s):  
Science Research ◽  
Accurate Estimation ◽  
Test Cases ◽  
Finite Element Models ◽  
Q Factor ◽  
Feature Models ◽  
End Conditions ◽  
Unrealistic Assumption ◽  
Fixed End ◽  
Plastic Parts

Abstract Snap-fit design has always been more of an art rather than a pure engineering science. Research in this area focuses on generating finite element models for predicting the performance of snap-fit features. Such research typically uses fixed end conditions at the base of the snap-fit feature. Often this is an unrealistic assumption, because snap-fits are usually molded on plastic parts with significant flexibility. The performance of snap-fits can be significantly influenced by this additional flexibility. To predict the performance of snap-fits in complex plastic parts, it has often been necessary to analyze the entire part, which can be a costly and time consuming process. There is no general methodology in the open literature to incorporate base-part flexibility into the design of snap-fit features. Existing work in this area such as Q-Factor charts, is inaccurate and specific to certain base-part and snap-fit topologies. This paper proposes a new methodology called structural abstraction for incorporating base-part flexibility into feature models. This methodology abstracts base-parts as spring elements with various stiffnesses. The theory behind this approach and the relevant relationships are developed and the approach is validated using several test cases. Independence of the approach to both base-part and snap-fit topologies is established and shown to be a major advantage of this technique. Use of this methodology will improve snap-fit analysis and give a more accurate estimation of retention strength. It is shown that in certain cases the improvement in accuracy can be as high as 70 percent or more.

The prediction of vehicle vibration transmitted to the occupant using a modular transfer matrix

2021 ◽  
pp. 107754632199759
Author(s):  
Jianchun Yao ◽  
Mohammad Fard ◽  
John L Davy ◽  
Kazuhito Kato
Keyword(s):  
Finite Element ◽  
Transfer Matrix ◽  
Dynamic Performance ◽  
Complex Structure ◽  
Vehicle Body ◽  
Computational Time ◽  
Accurate Estimation ◽  
Finite Element Models ◽  
Transfer Matrices ◽  
Body Vibration

Industry is moving towards more data-oriented design and analyses to solve complex analytical problems. Solving complex and large finite element models is still challenging and requires high computational time and resources. Here, a modular method is presented to predict the transmission of vehicle body vibration to the occupants’ body by combining the numerical transfer matrices of the subsystems. The transfer matrices of the subsystems are presented in the form of data which is sourced from either physical tests or finite element models. The structural dynamics of the vehicle body is represented using a transfer matrix at each of the seat mounting points in three triaxial (X–Y–Z) orientations. The proposed method provides an accurate estimation of the transmission of the vehicle body vibration to the seat frame and the seated occupant. This method allows the combination of conventional finite element analytical model data and the experimental data of subsystems to accurately predict the dynamic performance of the complex structure. The numerical transfer matrices can also be the subject of machine learning for various applications such as for the prediction of the vibration discomfort of the occupant with different seat and foam designs and with different physical characteristics of the occupant body.

An accurate estimation of bone density improves the accuracy of subject-specific finite element models

2008 ◽  
Vol 41 (11) ◽  
pp. 2483-2491 ◽  
Author(s):  
Enrico Schileo ◽  
Enrico Dall’Ara ◽  
Fulvia Taddei ◽  
Andrea Malandrino ◽  
Tom Schotkamp ◽  
...  
Keyword(s):  
Finite Element ◽  
Bone Density ◽  
Accurate Estimation ◽  
Finite Element Models ◽  
Subject Specific

Multiparametric Analysis of Resonance Peak Vibrations for Nonlinear Jointed Structures

2011 ◽  
Author(s):  
E. P. Petrov
Keyword(s):  
Finite Element ◽  
Degrees Of Freedom ◽  
Frequency Domain Analysis ◽  
Resonance Peak ◽  
Test Cases ◽  
Finite Element Models ◽  
Contact Interface ◽  
Interface Elements ◽  
Practical Test ◽  
Nonlinear Contact

A methodology has been developed to analyse and to optimize the resonance peak amplitudes and frequencies for essentially nonlinear periodic vibrations of jointed structures. The frequency domain analysis of realistic finite element models of jointed structures which can contain millions of degrees of freedom is performed. The detailed description of friction, gap and other types of the nonlinear contact interfaces in jointed structures is provided by contact interface elements. The resonance peak characteristics are calculated directly as functions of several parameters of contact interfaces and excitation. The efficiency of the methodology is demonstrated on a representative set of practical test cases.

Power Flow and Mechanical Intensity Calculations in Structural Finite Element Analysis

1990 ◽  
Vol 112 (4) ◽  
pp. 542-549 ◽  
Author(s):  
S. A. Hambric
Keyword(s):  
Finite Element ◽  
Power Flow ◽  
Shell Element ◽  
Test Cases ◽  
Finite Element Models ◽  
Element Analysis ◽  
Flow Paths ◽  
Input And Output ◽  
Test Models ◽  
Intensity Calculations

The identification of power flow paths in dynamically loaded structures is an important, but currently unavailable, capability for the finite element analyst. For this reason, methods for calculating power flows and mechanical intensities in finite element models are developed here. Formulations for calculating input and output powers, power flows, and mechanical intensities for beam and plate/shell element types are derived. NASTRAN is used to calculate the required velocity, force, and stress results of an analysis, which a post-processor then uses to calculate power flow quantities. Test models include a simple truss and a beam-stiffened cantilever plate. Both test cases showed reasonable power flow fields over low to medium frequencies.

ACCURACY OF SUBJECT-SPECIFIC FINITE ELEMENT MODELS IS IMPROVED BY ACCURATE ESTIMATION OF BONE DENSITY

2008 ◽  
Vol 41 ◽  
pp. S99
Author(s):  
Enrico Schileo ◽  
Enrico Dall'Ara ◽  
Fulvia Taddei ◽  
Andrea Malandrino ◽  
Tom Schotkamp ◽  
...  
Keyword(s):  
Finite Element ◽  
Bone Density ◽  
Accurate Estimation ◽  
Finite Element Models ◽  
Subject Specific

A Finite Element Analysis of the General Rolling Contact Problem for a Viscoelastic Rubber Cylinder

1988 ◽  
Vol 16 (1) ◽  
pp. 18-43 ◽  
Author(s):  
J. T. Oden ◽  
T. L. Lin ◽  
J. M. Bass
Keyword(s):  
Finite Element ◽  
Variational Principles ◽  
Standing Waves ◽  
Rolling Contact ◽  
Finite Element Models ◽  
Viscoelastic Cylinder ◽  
Element Analysis ◽  
Elastic Rubber ◽  
Frictional Effects ◽  
Rough Foundation

Abstract Mathematical models of finite deformation of a rolling viscoelastic cylinder in contact with a rough foundation are developed in preparation for a general model for rolling tires. Variational principles and finite element models are derived. Numerical results are obtained for a variety of cases, including that of a pure elastic rubber cylinder, a viscoelastic cylinder, the development of standing waves, and frictional effects.

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