A tolerance analysis model of CAD assemblies considering thermo-mechanical deformations of non-rigid parts

2021 ◽  
Author(s):  
A. Korbi ◽  
A. Soued ◽  
A. Ben Makhlouf ◽  
M. Graa ◽  
M. Tlija ◽  
...  
Keyword(s):  
Tolerance Analysis ◽  
Analysis Model ◽  
Mechanical Deformations

A Method for Integrating Form Errors Into Geometric Tolerance Analysis

2005 ◽  
Author(s):  
Robert Scott Pierce ◽  
David Rosen
Keyword(s):  
Manufacturing Process ◽  
High Speed ◽  
Tolerance Analysis ◽  
Analysis Model ◽  
Geometric Tolerance ◽  
Form Errors ◽  
Product Function ◽  
Component Models ◽  
Insight Into

In this research we describe a computer-aided approach to geometric tolerance analysis for assemblies and mechanisms. This new tolerance analysis method is based on the “generate-and-test” approach. A series of as-manufactured component models are generated within a NURBS-based solid modeling environment. These models reflect errors in component geometry that are characteristic of the manufacturing processes used to produce the components. The effects of different manufacturing process errors on product function is tested by simulating the assembly of these imperfect-form component models and measuring geometric attributes of the assembly that correspond to product functionality. A tolerance analysis model is constructed by generating-and-testing a sequence of component variants that represent a range of manufacturing process capabilities. The generate-and-test approach to tolerance analysis is demonstrated using a case study that is based on a high-speed stapling mechanism. As-manufactured models that correspond to two different levels of manufacturing precision are generated and assembly between groups of components with different precision levels is simulated. Misalignment angles that correspond to functionality of the stapling mechanism are measured at the end of each simulation. The results of these simulations are used to build a tolerance analysis model and to select a set of geometric form and orientation tolerances for the mechanism components. It is found that this generate-and-test approach yields insight into the interactions between individual surface tolerances that would not be gained using more traditional tolerance analysis methods.

New Tolerance Analysis Model for Normal Mean Shift in Manufacturing Process

2008 ◽  
Vol 594 ◽  
pp. 339-350 ◽  
Author(s):  
Chang Hsin Kuo ◽  
Jhy Cherng Tsai
Keyword(s):  
Normal Distribution ◽  
Uniform Distribution ◽  
Manufacturing Process ◽  
Mean Shift ◽  
Tolerance Analysis ◽  
Analysis Model ◽  
Normal Mean ◽  
The Mean ◽  
The Difference ◽  
Conventional Models

In this paper, we discuss the tolerance analysis methods for the component with a mean shift or drift. A new tolerance analysis model that assumes the mean shift in normal distribution rather than in uniform distribution is proposed. Simulation shows that the difference between the uniform distribution and normal distribution is 1.7%, which can be ignored, for mean shift to one standard deviation (σ). However, the difference becomes significant when the mean shift increases. The difference increases to 5.2% with 1.5σ shift, to 10.9% for 2σ shift, and up to 30.4% for 3σ shift. As normal distribution is a better model for statistical mean shift in manufacturing process, this investigation shows that the proposed tolerance analysis model can give a better model compared to conventional models.

Tolerance simulation of composite wingbox assembly considering preloading-modified distribution

2016 ◽  
Vol 36 (3) ◽  
pp. 224-232 ◽  
Author(s):  
Hua Wang ◽  
Jun Liu
Keyword(s):  
Probability Distribution ◽  
Tolerance Analysis ◽  
Tolerance Allocation ◽  
Analysis Model ◽  
Element Analysis ◽  
Content Type ◽  
Analysis Process ◽  
Final Assembly ◽  
Thickness Variations ◽  
Input Probability

Purpose Tolerance simulation’s reliability depends on the concordance between the input probability distribution and the real variation. The prescribed clamp force introduced changes in parts’ variation, which should be reflected in the input probability distribution for the tolerance simulation. The paper aims to present a tolerance analysis process of the composite wingbox assembly considering the preloading-modified distribution and especially focuses on the spring-in deviation of the thin-walled C-section composite beam (TC2B). Design/methodology/approach Based on finite element analysis model of TC2B, the preloading-modified probability distribution function (PDF) of the spring-in deviation is obtained. Thickness variations of the TC2B are obtained from the data of the downscaled composite wingbox. These variations are input to the computer-aided tolerance tools, and the final assembly variations are obtained. The assembly of the downscaled wingbox illustrates the effect of preloading on the probability distribution of the spring-in deviation. Findings The results have shown that the final assembly variations estimated with the modified probability distribution is more reliable than the variation of the initial normal distribution. Originality/value The tolerance simulation work presented in the paper will enhance the understanding of the composite parts assembling with spring-in deviations, improve the chance to choose assembling processes that allow specifications to be met and help with tolerance allocation in composites assembly.

scholarly journals Automated Point-based Tolerance Analysis Model Creation for Sheet Metal Parts

Procedia CIRP ◽  
2015 ◽  
Vol 27 ◽  
pp. 65-70 ◽  
Author(s):  
F. Litwa ◽  
M. Gottwald ◽  
M. Bohn ◽  
J.F. Klinger ◽  
M. Walter ◽  
...  
Keyword(s):  
Sheet Metal ◽  
Tolerance Analysis ◽  
Analysis Model ◽  
Metal Parts ◽  
Sheet Metal Parts

Tolerance Analysis: A New Model Based on Variational Solid Modelling

2010 ◽  
Author(s):  
Massimiliano Marziale ◽  
Wilma Polini
Keyword(s):  
Product Quality ◽  
Tolerance Analysis ◽  
Solid Modeling ◽  
Cost Ratio ◽  
Solid Modelling ◽  
Analysis Model ◽  
Worst Case ◽  
Quality Cost ◽  
New Model ◽  
Statistical Approaches

In mechanical fields products are usually made by assembling many parts. The dimensional and geometrical variations of each part has to be limited by tolerances able to ensure their manufacture, assembling, interchange-ability and a certain level of product quality. The tolerance analysis is the fundamental tool to foresee the effects of the tolerances assigned to the single components on the whole assembly and to optimize its quality-cost ratio. This work presents a new tolerance analysis model able to overcome the limits of the actual ones. It is based on the variational solid modeling and on the simplified hypothesis that each feature maintains its nominal shape. Its application is general. It allows to perform analysis by both worst case and statistical approaches. It may consider all the tolerance kinds, the Envelope and the Independence principles, the interaction among the tolerance zones and the joints with clearance among the components.

A Method for Integrating Form Errors Into Geometric Tolerance Analysis

2007 ◽  
Vol 130 (1) ◽  
Author(s):  
Robert Scott Pierce ◽  
David Rosen
Keyword(s):  
High Speed ◽  
Tolerance Analysis ◽  
Manufacturing Processes ◽  
Analysis Model ◽  
Geometric Tolerance ◽  
Form Errors ◽  
Product Function ◽  
Computer Aided ◽  
Component Models

In this research, we describe a computer-aided approach to geometric tolerance analysis for assemblies and mechanisms. A series of as-manufactured component models are generated within a NURBS-based solid modeling environment. These models reflect errors in component geometry that are characteristic of the manufacturing processes used to produce the components. The effects of different manufacturing process errors on product function are tested by simulating the assembly of imperfect-form component models and by measuring geometric attributes of the assembly that correspond to product functionality. A tolerance analysis model is constructed by generating and testing component variants that represent different manufacturing precision levels. The application of this approach to tolerance analysis is demonstrated using a case study that is based on a high-speed stapling mechanism.

Tolerance Analysis of a Three-Hinge Door System

2002 ◽  
Author(s):  
Xianmin Zhang ◽  
Arthur G. Erdman ◽  
Hong Zhang
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Tolerance Analysis ◽  
Positioning Error ◽  
Analysis Model ◽  
The Monte Carlo Method ◽  
Input Variables ◽  
Alignment Errors ◽  
Assembly Analysis

Tolerance analysis for assembly of a three co-linear hinges door system is studied in this paper. An analysis model is developed, in which the typical alignment errors between the pins and cylinders are included. The successful assembly conditions are presented. Simulations are carried out based on the models and the Monte Carlo method that predict successful assembly. Analysis results show that the positioning error, the distance between the axis of the pin and surface of the leaf, the thickness of the leaf and the depth of the mortise are the top 3 sensitive input variables in the system.

Computer-Aided Design/Tolerancing Integration: A Novel Tolerance Analysis Model of Assemblies With Composite Positional Defects and Deformations of Nonrigid Parts

2021 ◽  
Vol 143 (8) ◽  
Author(s):  
A. Korbi ◽  
M. Tlija ◽  
B. Louhichi
Keyword(s):  
Computer Aided Design ◽  
Tolerance Analysis ◽  
Cad Model ◽  
Analysis Model ◽  
Tolerance Zone ◽  
Manufacturing Defects ◽  
Material Condition ◽  
Computer Aided ◽  
Positional Tolerance ◽  
Aided Design

Abstract Nowadays, the tolerancing integration in computer-aided design (CAD) tools remains among the major goals of mechanical manufacturers. In the virtual product development, ideal and rigid models are used in the digital mockup (DMU). Hence, research works developed integrated CAD models for tolerance analysis, while considering manufacturing defects. However, the tolerance analysis in the case of composite positional tolerance for feature patterns, commonly used in the industry, becomes a difficult activity with the consideration of parts deformations. Thus, this paper presents a novel CAD model for the tolerance analysis considering composite positional defect of features set and nonrigid component deformations due to external mechanical loads. The modeling of rigid components with dimensional defects is established based on the numerical perturbation method. Indeed, the relationships between driving and driven dimensions are determined to obtain the configurations in maximum and least material of the CAD model. Thereafter, the geometrical deviations are modeled by face displacements. The modeling of composite positional errors is performed while respecting the feature relating position tolerance zone framework and the pattern-location tolerance zone framework constraints, as well as the maximum or least material condition. The deviations caused by nonrigid part deformations are considered by the integration of finite element results into the CAD model. The realistic configurations of the assembly are obtained after the updating of mating constraints between rigid and nonrigid parts with defects. The composite positional tolerance is analyzed with the simulation of relative motion between parts. A case study is proposed to evaluate the developed tolerancing method.

scholarly journals A NURBS-based solid modeling to enhance rapid prototyping in the restoration of decorative elements

2020 ◽  
Author(s):  
Michele Calì ◽  
Salvatore Massimo Oliveri ◽  
Placido Calì ◽  
Rita Ambu
Keyword(s):  
Experimental Data ◽  
Rapid Prototyping ◽  
Tolerance Analysis ◽  
Solid Modeling ◽  
High Accuracy ◽  
Three Dimensions ◽  
Reconstruction Method ◽  
Solid Modelling ◽  
Analysis Model ◽  
Computer Aided

Abstract In this research, we describe a computer-aided approach to improve the reconstruction method of decorum in architectural surfaces and sculpture. The effects of withdrawal caused by catalysis of mold in silicone was evaluated and simulated by a NURBS-based solid modelling. A tolerance analysis model was developed to predict manufacturing precision levels. In particular, differential increment along three dimensions was performed considering different volume distributions. The methodology was validated by experimental data obtained during the coffered ceiling restoration of Teatro Massimo Vittorio Emanuele in Palermo. The proposed methodology allowed the reconstruction of decorations or fragments of decoration with high accuracy.

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