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.

Assembly tolerance analysis based on the Jacobian model and skin model shapes

2019 ◽  
Vol 39 (2) ◽  
pp. 245-253 ◽  
Author(s):  
Ting Liu ◽  
Yan-Long Cao ◽  
Qijian Zhao ◽  
Jiangxin Yang ◽  
Lujun Cui
Keyword(s):  
Product Life Cycle ◽  
Tolerance Analysis ◽  
Quality Level ◽  
Functional Requirements ◽  
Skin Model ◽  
Content Type ◽  
Kinematic Chains ◽  
Assembly Tolerance ◽  
Geometric Tolerances ◽  
Functional Features

Purpose The purpose of this paper is to carry out an assembly tolerance analysis by means of a combined Jacobian model and skin model shape. The former is based on small displacements modeling of points using 6 × 6 transformation matrices of open kinematic chains in robotics. The latter easily models toleranced features with all kinds of geometric deviations. Design/methodology/approach This paper presents the procedure of performing tolerance analysis by means of the Jacobian model and skin model shape for assemblies. The point cloud-based discrete representative is able to model the actual toleranced surfaces instead of the ideal or associated ones in an assembly, which brings the simulation tools closer to reality. Findings The proposed method has the advantage of skin model shape which is suitable for geometric tolerances management along the product life cycle and contact analysis of kinematic small variations, as well as, with the Jacobian, enabling transformation of locally expressed parts deviations to globally expressed functional requirements. The result of the case study shows the accuracy of the method. Research limitations/implications The proposed approach has not been developed fully; other functional features such as the pyramid are still ongoing challenges. Practical implications It is an effective method for supporting design, manufacturing and inspection by providing a quantitative analysis of the effects of multi-tolerances on the final functional key characteristics and for predicting the quality level. Originality/value The paper is original in taking advantages of both Jacobian model and skin model shape to consider all geometric tolerances in assembly.

scholarly journals Determination of the rational constructive form of cellular communication towers

2019 ◽  
Vol 20 (2) ◽  
pp. 163-173
Author(s):  
Alexander V. Golikov ◽  
Elena A. Mikhalchonok
Keyword(s):  
Cellular Communication ◽  
Geometric Parameters ◽  
Design Stage ◽  
High Rise ◽  
Optimal Values ◽  
Lattice Towers ◽  
Definition Of ◽  
The Relationship ◽  
Communication Towers

The need for reliable supports for locating and maintaining the equipment of cellular opera-tors is increasing every year. The classic version of the supports are lattice towers. At present, optimization of the parameters of lattice towers, which is one of the ways to improve the efficiency of their design and construction, is of great importance. The purpose of the work is chosen definition of a rational constructive form of lattice cellular communication towers. In the work, the calculation and analysis of the tower supports of a prismatic and pyramidal form are made with varying basic geometric parameters of the structure and the ratio of parameters between them. To create basic dependencies, numerical modeling methods are used. According to the results of a critical analysis of the literature on the calculation of lattice supports of high-rise buildings, the absence of recommended optimal values of the geometric parameters of structures and the relationship between them was established. The stress-strain state of the design models of lattice towers of a prismatic and pyramidal shape was assessed with variation of the main overall geometric parameters of the structures. To achieve the goal of finding a rational structural form of lattice supports, two rationalization criteria have been tested and applied - the simultaneous fulfillment of the requirements of both limiting states and minimization of the mass of the structure. The results of the study of lattice tower supports are presented in dimensionless parameters, which can be applied by the engineer when assigning the overall dimensions of the structure at the initial design stage.

scholarly journals Tolerance Analysis of Mechanical Parts

2020 ◽  
Vol 14 (3) ◽  
pp. 265-272
Author(s):  
Živko Kondić ◽  
Đuro Tunjić ◽  
Leon Maglić ◽  
Amalija Horvatić Novak
Keyword(s):  
Tolerance Analysis ◽  
Case Method ◽  
Worst Case ◽  
Mechanical Parts ◽  
Assembly Tolerance ◽  
Huge Impact ◽  
Quality Of Products ◽  
The One

The determination of tolerances has a huge impact on the price and quality of products. The objective of tolerance analysis is to provide the widest possible tolerance range of parts, without disturbing the functionality of the assembly. Tolerance analysis should be performed during the design process because then there is still the possibility for change. For the purpose of carrying out the analysis, three methods will be used: Worst Case method, Root Sum Square method and Monte Carlo Simulation. Methods are explained through simple examples and applied on the one-way clutch.

Geometric tolerance analysis through Jacobian model for rigid assemblies with translational deviations

2016 ◽  
Vol 36 (1) ◽  
pp. 72-79 ◽  
Author(s):  
Wilma Polini ◽  
Andrea Corrado
Keyword(s):  
Tolerance Analysis ◽  
Geometric Error ◽  
Functional Requirements ◽  
Content Type ◽  
Geometric Tolerances ◽  
Mechanical Assemblies ◽  
Geometric Deviations ◽  
2D And 3D ◽  
Practical Implications

Purpose – The purpose of this paper is to carry out a tolerance analysis with geometric tolerances by means of the Jacobian model. Tolerance analysis is an important task to design and to manufacture high-precision mechanical assemblies; it has received considerable attention by the literature. The Jacobian model is one of the methods proposed by the literature for tolerance analysis. The Jacobian model cannot deal with geometric tolerances for mechanical assemblies. The geometric tolerances may not be neglected for assemblies, as they significantly influence their functional requirements. Design/methodology/approach – This paper presents how it is possible to deal with geometric tolerances when a tolerance analysis is carried out by means of a Jacobian model for a 2D and 3D assemblies for which the geometric tolerances applied to the components involve only translational deviations. The three proposed approaches modify the expression of the stack-up function to overcome the shortage of Jacobian model that the geometric error cannot be processed. Findings – The proposed approach has been applied to a case study. The results of the case study show how, when a statistical approach is implemented, the Jacobian model with the three developed methods gives results very similar to those due to other models of the literature, such as vector loop and variational. Research limitations/implications – In particular, the proposed approach may be applied only when the applied geometrical tolerances involve translational variations in 3D assemblies. 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 of the manufacturing costs. Originality/value – The original contribution of the paper is due to three methods to make a Jacobian model able to consider form and geometric deviations.

A generic integrated approach of assembly tolerance analysis based on skin model shapes

2020 ◽  
pp. 095440542095886
Author(s):  
Yang Yi ◽  
Xiaojun Liu ◽  
Tingyu Liu ◽  
Zhonghua Ni
Keyword(s):  
Tolerance Analysis ◽  
Integrated Approach ◽  
Design Stage ◽  
Variation Theory ◽  
Contact Method ◽  
Skin Model ◽  
Manufacturing Defects ◽  
Assembly Tolerance ◽  
Contact Points ◽  
Assembly Deviation

Nowadays, assembly tolerance analysis has become a challenging problem to predict the accuracy of a final assembly and examine whether specified tolerances satisfy assembly functional requirements (AFRs) for ensuring product assembly performance. Skin model shapes can be addressed to represent part geometric tolerances with manufacturing defects, thereby providing high fidelity surfaces that can replace nominal or ideal surfaces and significantly improve the accuracy and reliability of assembly tolerance analysis. However, their application in easy-to-use assembly simulation is limited by the level of detail required for manufacturing defect simulation and the complicated calculation process for integrating these defects into the tolerance analysis. Therefore, to overcome these issues in predicting assembly deviations in the early design stage, we propose a generic integrated approach of assembly tolerance analysis based on skin model shapes. First, two methods are introduced for modelling and generating skin model shapes according to different mate types of assembly key features. Second, a calculation method of assembly deviation propagation is developed by the integration of skin model shapes and stream-of-variation theory with accuracy and efficiency guarantees. Besides, a slightly modified relative contact positioning method is presented, based on different surface and progressive contact method, to obtain deterministic contact points and contact positioning errors between key mating joint surfaces. And then, the deviation values of AFRs are calculated, considering the inevitable manufacturing and assembly process errors. Finally, a typical mechanical assembly on assembly tolerance analysis is used as a case study to demonstrate the effectiveness of the proposed approach.

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.

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.

Tolerance Design for Optimal Dimensional Quality of Machine Parts

2016 ◽  
Vol 841 ◽  
pp. 65-71
Author(s):  
Gabriel Frumuşanu ◽  
Alexandru Epureanu
Keyword(s):  
Tolerance Analysis ◽  
Life Cycles ◽  
Manufacturing Cost ◽  
Tolerance Design ◽  
Functional Requirements ◽  
Conceptual Approach ◽  
Geometrical Features ◽  
Geometric Deviations ◽  
Tolerance Zones ◽  
New Criterion

The mechanical systems consist of assembled parts, between which diverse interactions take place. Tolerance analysis purpose is to study the effects of part geometric deviations on assembly functional requirements. In the current approaches from this field, the part geometrical deviations are toleranced without considering the evolution of the geometrical deviations during product exploitation. As consequence, between two parts identical as type but with different values of their geometrical features, inside the designed tolerance zones, any difference is made despite they might have significantly different life cycles or manufacturing costs. This paper presents a new conceptual approach concerning parts tolerance design, based on a new criterion, namely the dimensional quality, defined by two important features: life cycle and manufacturing cost. The main issue of this approach is the optimal relation between the manufacturing tolerance zones and the acceptable functional deviation domain. The new concept implementation is sampled in the case of an articulated arm.

scholarly journals THE BUILT ENVIRONMENT OF FARM WINERIES: AN ANALYSIS METHODOLOGY FOR DEFINING META-DESIGN REQUIREMENTS

2012 ◽  
Vol 42 (3) ◽  
pp. 25
Author(s):  
Patrizia Tassinari ◽  
Sergio Galassi ◽  
Stefano Benni ◽  
Daniele Torreggiani
Keyword(s):  
Building Design ◽  
Landscape Design ◽  
Functional Requirements ◽  
Production Parameters ◽  
Farm Production ◽  
Analysis Methodology ◽  
Emilia Romagna Region ◽  
Main Production ◽  
Design Requirements ◽  
Definition Of

The study represents the first step of a broader research aimed at outlining specific building and landscape design criteria for small to medium-sized farm wineries. With reference to a study area of the Emilia- Romagna region (Italy) representative of the regional wine-growing and producing sector, the specific aims of the study are the identification and quantification of the main production parameters, and the formulation of a preliminary framework of dimensional and functional requirements of wineries. We acquired, georeferenced, and analysed the available databases about wine farm production and sizes. We analysed a representative sample of such farms and the national and local codes about building design for that sector. The study has led to the definition of the main characters of the production process and a layout of the main parameters influencing the design process.

scholarly journals SIMULTANEOUS DEFINITION OF KEY CHARACTERISTICS IN ORDER TO FACILITATE ROBUST DESIGN IN EARLY PRODUCT DEVELOPMENT STAGES

2021 ◽  
Vol 1 ◽  
pp. 2691-2700
Author(s):  
Stefan Goetz ◽  
Dennis Horber ◽  
Benjamin Schleich ◽  
Sandro Wartzack
Keyword(s):  
Product Development ◽  
Robust Design ◽  
Language Processing ◽  
Design Stage ◽  
Concept Design ◽  
Clear Definition ◽  
Implicit Information ◽  
Key Characteristics ◽  
Associated Functions ◽  
Definition Of

AbstractThe success of complex product development projects strongly depends on the clear definition of target factors that allow a reliable statement about the fulfilment of the product requirements. In the context of tolerancing and robust design, Key Characteristics (KCs) have been established for this purpose and form the basis for all downstream activities. In order to integrate the activities related to the KC definition into product development as early as possible, the often vaguely formulated requirements must be translated into quantifiable KCs. However, this is primarily a manual process, so the results strongly depend on the experience of the design engineer.In order to overcome this problem, a novel computer-aided approach is presented, which automatically derives associated functions and KCs already during the definition of product requirements. The approach uses natural language processing and formalized design knowledge to extract and provide implicit information from the requirements. This leads to a clear definition of the requirements and KCs and thus creates a founded basis for robustness evaluation at the beginning of the concept design stage. The approach is exemplarily applied to a window lifter.

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