Fuzzy Tolerance Analysis of 3-D Mechanical Assemblies

1997 ◽  
Author(s):  
K. Srikanth ◽  
F. W. Liou ◽  
S. N. Balakrishnan
Keyword(s):  
Fuzzy Logic ◽  
Manufacturing Process ◽  
Three Dimensional ◽  
Tolerance Analysis ◽  
Tolerance Design ◽  
Cost Information ◽  
Assembly Tolerance ◽  
Mechanical Assemblies ◽  
Representation Scheme ◽  
Tolerance Assignment

Abstract Tolerance design is interdisciplinary in nature and is characterized by a highly uncertain environment. In recent years, fuzzy logic has appeared as a credible alternative for tolerance design. In this paper a fuzzy based tolerance representation scheme is presented to model three dimensional (3-D) tolerances. With this representation, relative assembly tolerance constraints can be expressed. A fuzzy tolerance generation and assignment process for assembly is discussed. Fuzzy tolerance equations are generated for 3-D assembly considerations. Manufacturing process information, along with uncertain cost information modeled in fuzzy terms, is added to the system to arrive at a cost-optimal tolerance assignment.

Computer Aided Tolerance Analysis of Parts and Assemblies

1989 ◽  
Author(s):  
R. T. Scott ◽  
G. A. Gabriele
Keyword(s):  
Real World ◽  
Probability Distributions ◽  
Three Dimensional ◽  
Tolerance Analysis ◽  
The Real ◽  
Assembly Tolerance ◽  
Computer Aided ◽  
Probability Information ◽  
Exact Constraint

Abstract An exact constraint scheme based on the physical contacting constraints of real part mating features is used to represent the process of assembling the parts. To provide useful probability information about how assembly dimensions are distributed when the parts are assembled as intended, the real world constraints that would prevent interference are ignored. This work addresses some limitations in the area of three dimensional assembly tolerance analysis. As a result of this work, the following were demonstrated: 1. Assembly of parts whose assembly mating features are subjected to variation; 2. Assemble parts using a real world set of exact constraints; 3. Provide probability distributions of assembly dimensions.

Computer-Aided Monte Carlo Aircraft Tolerance Design Based on UG

2011 ◽  
Vol 338 ◽  
pp. 300-303
Author(s):  
Chang Hong Guo ◽  
Ping Xi ◽  
Zhen Yu Wang ◽  
Xing Dong Li
Keyword(s):  
Monte Carlo ◽  
Three Dimensional ◽  
Integrated Design ◽  
Tolerance Analysis ◽  
Digital Design ◽  
Tolerance Design ◽  
Computer Aided ◽  
Design And Manufacture

Along with the CAD technology being popularized, three-dimensional design of aircraft is ultimately realized into digital design. However, aircraft tolerances have not been designed by computer. They are mainly based on lots of manual calculations and not coordinated with integrated design and hold back the development of aircraft digital design and manufacture technologies. This paper introduces how to develop computer-aided aircraft tolerance analysis and distribution modules on UG and introduces Monte Carlo tolerance analysis technology. Running instances of aircraft tolerance design are illustrated in the paper.

A Comprehensive Tolerancing System for 3D Mechanical Assemblies

2010 ◽  
Vol 139-141 ◽  
pp. 1289-1293 ◽  
Author(s):  
Dong Ya Yang ◽  
Jun Gong
Keyword(s):  
Design Principle ◽  
Tolerance Analysis ◽  
Automatic Generation ◽  
Geometric Feature ◽  
Design Practice ◽  
Simulation Environment ◽  
Assembly Tolerance ◽  
Detail Design ◽  
Comprehensive Method ◽  
Mechanical Assemblies

A comprehensive tolerancing system is presented with its design principle, system architecture and key functions. The following functional modules, automatic generation of dimension chain, equivalent variational mechanism (EVM) modeling and visualized 3D tolerance analysis, are described in detail. Design intent is expressed by assembly tolerance specifications, which may be added to the model and used in computing predicted quality levels. A comprehensive method, based on equivalent replacement, has been developed for modeling variations in 3D mechanical assemblies. The models are constructed of common engineering elements: dimension chain, kinematic joints, assembly datums, dimensional and geometric feature tolerances, and assembly tolerance limits. The method is consistent with engineering design practice and is well suited for integration with commercial CAD systems. To make the tolerancing system robust and efficient, new functionalities are added to well-known CAD software and simulation environment. Tested by many samples, this system shows good robustness and practicability.

Visualized Equivalent Variational Modeling in Tolerance Analysis of 3D Mechanical Assemblies

2011 ◽  
Vol 201-203 ◽  
pp. 229-233
Author(s):  
Dong Ya Yang ◽  
Jun Gong
Keyword(s):  
Kinematic Model ◽  
Tolerance Analysis ◽  
Geometric Feature ◽  
Velocity Analysis ◽  
Assembly Tolerance ◽  
Variational Modeling ◽  
Mechanical Assemblies ◽  
Dimensional Variation ◽  
Kinematic Joint

This paper introduces a new, visualized approach for including all the geometric feature variations in the tolerance analysis of mechanical assemblies. It focuses on how to characterize geometric feature variations in vector-loop-based assembly tolerance models. The characterization will be used to help combine the effects of all variations within an assembly in order to perform tolerance analysis of mechanical assemblies by employing commercial 3D kinematic software (e.g. ADAMS). Equivalent variational modeling, based on TAKS method, has been developed for modeling variations in 3D mechanical assemblies. Create a library of Equivalent Variational Joints (EVJs) to allow inclusion all kinds of variations in analysis, and allow the kinematic model to include both geometric and dimensional variation in a velocity analysis. EVJ, for use in tolerance analysis, was developed for commonly used 3D kinematic joint types, and was implemented with examples to explain their use to form Equivalent Variational Mechanisms (EVMs).

scholarly journals Reliability-based tolerance redesign of mechanical assemblies using Jacobian-Torsor model

2021 ◽  
Vol 104 (2) ◽  
pp. 003685042110132
Author(s):  
Bingxiang Wang ◽  
Xianzhen Huang ◽  
Miaoxin Chang
Keyword(s):  
Optimization Model ◽  
Economic Effect ◽  
Tolerance Analysis ◽  
Lambert W Function ◽  
Mechanical Assembly ◽  
Assembly Tolerance ◽  
Tolerance Optimization ◽  
Geometric Tolerances ◽  
Mechanical Assemblies ◽  
Proposed Model

The purpose of this paper is to present a new method to redesign dimensional and geometric tolerances of mechanical assemblies at a lower cost and with higher reliability. A parametric Jacobian-Torsor model is proposed to conduct tolerance analysis of mechanical assembly. A reliability-based tolerance optimization model is established. Differing from previous studies of fixed process parameters, this research determines the optimal process variances of tolerances, which provide basis for the subsequent assembly tolerance redesign. By using the Lambert W function and the Lagrange multiplier method, the analytical solution of the parametric tolerance optimization model is obtained. A numerical example is presented to demonstrate the effectiveness of the model, while the results indicate that the total cost is reduced by 10.93% and assembly reliability improves by 2.12%. This study presents an efficient reliability-based tolerance optimization model. The proposed model of tolerance redesign can be used for mechanical assembly with a better economic effect and higher reliability.

Tolerance-based Variations in Solid Modeling

2003 ◽  
Vol 3 (4) ◽  
pp. 345-352 ◽  
Author(s):  
G. Moroni ◽  
W. Polini
Keyword(s):  
Tolerance Analysis ◽  
Design Stage ◽  
Tolerance Design ◽  
Functional Requirements ◽  
Mechanical Parts ◽  
Assembly Tolerance ◽  
Geometric Tolerances ◽  
Design Requirements ◽  
Optimal Values ◽  
Definition Of

Information on tolerances and attributes of mechanical parts and assemblies is crucial for many activities in a product’s life cycle. Tolerance design is a complex task because many factors (functional, technological and economical) should be considered. It is an iterative process, starting from a first tolerances assignment and ending with the definition of their optimal values. Once all tolerances have been assigned to each part of an assembly, tolerance analysis is performed. This stage aim is to evaluate if the combined effects of the assigned tolerances let the design requirements be met. Then, feasible and economical aspects are considered on the basis of both available processes and cost evaluations. The whole tolerance design stage is usually defined as tolerance synthesis. The focus of this work is the discussion of the algorithms to model the geometrical variations, of each part of an assembly, allowed by geometric tolerances. This involves the change of the boundary nominal representation of a part face on the basis of the assigned dimensional and geometric tolerances. At present, the developed algorithms are able to simulate flatness, location and orientation. The modified parts, generated by tolerance simulation, may be used to evaluate the overall assemblability and, then, to verify the assembly functional requirements.

A variational model for 3D tolerance analysis with manufacturing signature and operating conditions

2018 ◽  
Vol 38 (1) ◽  
pp. 10-19 ◽  
Author(s):  
Andrea Corrado ◽  
Wilma Polini ◽  
Giovanni Moroni ◽  
Stefano Petrò
Keyword(s):  
Three Dimensional ◽  
Reference Value ◽  
Tolerance Analysis ◽  
Geometrical Model ◽  
Operating Conditions ◽  
Variational Model ◽  
Assembly Process ◽  
Functional Requirements ◽  
Content Type ◽  
Mechanical Assemblies

Purpose The purpose of this work is to present a variational model able to deal with form tolerances and assembly conditions. The variational model is one of the methods proposed in literature for tolerance analysis, but it cannot deal with form tolerances and assembly conditions that may influence the functional requirements of mechanical assemblies. Design/methodology/approach This work shows how to manage the actual surfaces generated by the manufacturing process and the operating conditions inside the variational model that has been modified to integrate the manufacturing signature left on the surfaces of the parts and the operating conditions that arise during an actual assembly, such as gravity and friction. Moreover, a geometrical model was developed to numerically simulate what happens in a real assembly process and to give a reference value. Findings The new variational model was applied to a three-dimensional case study. The obtained results were compared to those of the geometrical model and to those of the variational model to validate the new model and to show the improvements. Research limitations/implications The proposed approach may be extended to other models of literature. However, its limitation is that it is able to deal with a sphere–plane contact. Practical implications Tolerance analysis is a valid tool to foresee geometric interferences among the components of an assembly before getting the physical assembly. It involves a decrease in the manufacturing costs. Originality/value The main contributions of the study are the insertion of a systematic pattern characterizing the features manufactured by a process, assembly operating conditions and development of a geometrical model to reproduce what happens in a real assembly process.

Technique of Extrusion Die Tolerance Analysis Based on CAT

2014 ◽  
Vol 941-944 ◽  
pp. 1777-1781
Author(s):  
Yuan Lou Gao ◽  
Zhe Li ◽  
Xin Wang
Keyword(s):  
Manufacturing Process ◽  
Tolerance Analysis ◽  
Chemical Characteristics ◽  
Tolerance Design ◽  
Generation Algorithm ◽  
Extrusion Die ◽  
Tolerance Modeling ◽  
Screw Extrusion ◽  
Computer Aided ◽  
Manual Calculation

As traditional screw extrusion die tolerance analysis has characteristics like manual calculation, experience dependence so far, this paper aims at applying CAT (Computer Aided Tolerancing) into extrusion field with the assistance of tolerance modeling and self-generation algorithm of retrieval dimension chain to analyze tolerance and reassign tolerance based on the technology used for aircraft assembly referring to chemical characteristics of the manufacturing process. Practice on production line testified the rationality of improved tolerance design.

Three Dimensional Assembly Tolerance Analysis of Gear Drivetrain

2013 ◽  
Vol 655-657 ◽  
pp. 1656-1661
Author(s):  
Xiao Long Li ◽  
Gui Hua Li ◽  
Jun Ying Wang ◽  
Hui Wang
Keyword(s):  
Three Dimensional ◽  
Tolerance Analysis ◽  
Assembly Tolerance ◽  
Analysis Process ◽  
Assembly Accuracy ◽  
3D Assembly ◽  
Prediction And Control ◽  
And Control ◽  
Assembly Error ◽  
Assembly Analysis

Assembly accuracy has a crucial impact on the movement, load and fatigue of gear drivetrain. In this paper, a methodology on the accuracy prediction and control of complex drivetrain is presented. The proposed approach tries to simplify the assembly tolerance computation but grasping main assembly error factors in the assembly process of gear drivetrain. Jacobian -Torsor method is used in the analysis process, and results show a proper performance which indicates a potential opportunity for further deep and wide research on the 3D assembly analysis and simplification method.

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