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.

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 novel method to design tolerance of aero-engine casing by integrating 3-D assembly tolerance with performance instability

2021 ◽  
pp. 095440542110609
Author(s):  
Hehe Kang ◽  
Zhi-Min Li ◽  
Tao Liu ◽  
Wei Yuan ◽  
Yuping Wu
Keyword(s):  
Natural Frequency ◽  
Dynamic Performance ◽  
Tolerance Analysis ◽  
Frequency Distributions ◽  
Assembly Tolerance ◽  
Aero Engine ◽  
Novel Method ◽  
Tolerance Model ◽  
Assembly Deviation ◽  
The Given

Assembly quality of aero-engine casing plays a key role in the whole aero-engine, since it is directly related to the final function and dynamic performance. However, during the design phase, the tolerance analysis is usually conducted independently without any consideration of the effect on the dynamic characteristic. This paper aims to integrate manufacturing precision with dynamic performance instability together. First, the 3-D tolerance model of the aero-engine casing is constructed based on the Jacobian-Torsor theory. The target deviation from the tolerance model is defined as the input variable into the vibratory governing equation. Then, the effect of 3-D assembly deviation on the natural frequency is studied. The corresponding frequency distributions for different vibration modes are illustrated. Finally, the mapping relationship between assembly tolerance and fluctuation ratio of natural frequency is established through the 3-D fitted surface. Under the given constraint of performance stability, the optimized tolerance zone is obtained. This work provides a significant guidance for performance improvement and tolerance design in the aero-engine casing assembly.

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.

Integrated approach for assembly tolerance analysis

2001 ◽  
Vol 39 (7) ◽  
pp. 1517-1535 ◽  
Author(s):  
K. Srikanth ◽  
F. W. Liou ◽  
S. N. Balakrishnan
Keyword(s):  
Tolerance Analysis ◽  
Integrated Approach ◽  
Assembly Tolerance

Process Signature Modeling for Tolerance Analysis

2010 ◽  
Vol 10 (2) ◽  
Author(s):  
R. Ascione ◽  
W. Polini ◽  
Q. Semeraro
Keyword(s):  
Concurrent Engineering ◽  
Manufacturing Process ◽  
Tolerance Analysis ◽  
Actual Surface ◽  
Contact Points ◽  
Geometric Tolerances ◽  
Systematic Pattern ◽  
Process Signature ◽  
Nominal Surface

Many well-known approaches exist in the literature for tolerance analysis. All the methods proposed in the literature consider the dimensional and the geometric tolerances applied to some critical points (contact points among profiles belonging to couples of parts) on the surface of the assembly components. These points are generally considered uncorrelated since the nominal surface is considered. Therefore, the methods proposed in the literature do not consider the actual surface due to a manufacturing process. Every manufacturing process leaves on the surface a signature, i.e., a systematic pattern that characterizes all the features machined with that process. The aim of the present work is to investigate the effects of considering the manufacturing signature in solving a tolerance stack-up function. A case study involving three parts has been defined and solved by means of a method of the literature, the variational method, with and without considering the correlation among the points of the same surface due to the manufacturing signature. This work represents a first step toward the integration of the design and the manufacturing in a concurrent engineering approach.

scholarly journals BIM and DfMA: A Paradigm of New Opportunities

2021 ◽  
Vol 13 (17) ◽  
pp. 9591
Author(s):  
Sepehr Abrishami ◽  
Rocío Martín-Durán
Keyword(s):  
Literature Review ◽  
Conceptual Framework ◽  
Energy Use ◽  
Integrated Approach ◽  
Design Stage ◽  
Extensive Literature ◽  
Sources Of Information ◽  
Construction Methods ◽  
Wide Range

The main goal of this study is to explore the adoption of a design for manufacturing and assembly (DfMA) and building information management (BIM) approach during the whole lifecycle of assets. This approach aims to tackle issues inherent in the design of traditional construction methods, such as low productivity and quality, poor predictability and building performance, and energy use, through the implementation of a BIM library of off-site components. In recent years, a renewed interest has been directed to the attempt to provide solutions to these urgent problems through the adoption of new advancements in technologies. However, while there are studies focussing on a BIM-DfMA approach, there is a lack of research regarding how this approach should be adopted during the whole lifecycle of the assets. Furthermore, to the best of our knowledge, defining an efficient way of developing a component-based BIM object library has not yet been included in any of the available studies. A mixed methodology approach has been used in this research. A conceptual framework was developed as the result of an extensive literature review to investigate new advancements in the AEC sector. Following the literature review, the framework was tested and validated through a case study based on the production and adoption of a BIM library of off-site components at the design stage of an asset. The architecture, engineering, and construction (AEC) industry has recognised the necessity of a new approach that helps to resolve the well-known issues presented in traditional methods of construction. The conceptual framework and case study proposed presents a valuable new method of construction that support the implementation of a BIM and DfMA approach, highlighting their benefits. This framework has been created using many valuable and reliable sources of information. The result of this research supports the idea of a novel new construction method that focuses on a manufacturing-digital-driven industry, with the use of DfMA in a BIM-integrated approach. This novel method will add significance and be beneficial for a wide range of aspects in the construction sector, contributing to the theoretical and practical domain.

Fuzzy Sensitivity Analysis in the Context of Dimensional Management

2018 ◽  
Vol 5 (1) ◽  
Author(s):  
Thomas Oberleiter ◽  
Björn Heling ◽  
Benjamin Schleich ◽  
Kai Willner ◽  
Sandro Wartzack
Keyword(s):  
Tolerance Analysis ◽  
Design Stage ◽  
Special Focus ◽  
Total System ◽  
Early Design Stage ◽  
Technical Requirements ◽  
Geometric Deviations ◽  
Weak Points ◽  
Dimensional Management ◽  
The Impact

Real components always deviate from their ideal dimensions. This makes every component, even a serial production, unique. Although they look the same, differences can always be observed due to different scattering factors and variations in the manufacturing process. All these factors inevitably lead to parts that deviate from their ideal shape and, therefore, have different properties than the ideal component. Changing properties can lead to major problems or even failure during operation. It is necessary to specify the permitted deviations to ensure that every single product nevertheless meets its technical requirements. Furthermore, it is necessary to estimate the consequences of the permitted deviations, which is done via tolerance analysis. During this process, components are assembled virtually and varied with the uncertainties specified by the tolerances. A variation simulation is one opportunity to calculate these effects for geometric deviations. Since tolerance analysis enables engineers to identify weak points in an early design stage, it is important to know the contribution that every single tolerance has on a certain quality-relevant characteristic, to restrict or increase the correct tolerances. In this paper, a fuzzy-based method to calculate the sensitivity is introduced and compared with the commonly used extended Fourier amplitude sensitivity test (EFAST) method. Special focus of this work is the differentiation of the sensitivity for the total system and the sensitivities for the subsystems defined by the α-cuts of the fuzzy numbers. It discusses the impact of the number of evaluations and nonlinearity on sensitivity for EFAST and the fuzzy-based method.

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.

A New Tolerance Analysis Method for Designers and Manufacturers

1987 ◽  
Vol 109 (2) ◽  
pp. 112-116 ◽  
Author(s):  
W. H. Greenwood ◽  
K. W. Chase
Keyword(s):  
Tolerance Analysis ◽  
New Method ◽  
Analysis Method ◽  
Worst Case ◽  
Assembly Tolerance ◽  
Naturally Occurring ◽  
Methods Of Analysis

Even when all manufactured parts for an assembly are produced within limits, these parts still may not assemble properly if the assembly tolerance analysis was inadequately performed. Naturally occurring shifts in a process can produce biased distributions which can result in increased assembly problems and a greater number of rejects than anticipated. The most common methods of analysis of assembly tolerance buildup are worst case and root sum squares. The limitations of each of these methods are discussed and a simple new method is proposed which accounts for expected bias. This new method includes both worst case and root sum squares as extreme cases.

Comparison of Different Sensitivity Analysis Methods in the Context of Dimensional Management

2017 ◽  
Author(s):  
Björn Heling ◽  
Thomas Oberleiter ◽  
Benjamin Schleich ◽  
Kai Willner ◽  
Sandro Wartzack
Keyword(s):  
Tolerance Analysis ◽  
Sensitivity Analyses ◽  
Design Stage ◽  
Fuzzy Arithmetic ◽  
Early Design Stage ◽  
Technical Requirements ◽  
Strongly Connected ◽  
Geometric Deviations ◽  
Comparison Of The Results ◽  
Dimensional Management

Although mass production parts look the same, every manufactured part is unique, at least on a closer inspection. The reason for this is that every manufactured part is inevitable subjected to different scattering influencing factors and variation in the manufacturing process, such as varying temperatures or tool wear. All these factors inevitably lead to parts, which deviate from their ideal shape. Products, which are built from these deviation-afflicted parts consequently show deviations from their ideal properties. To ensure that every single product nevertheless meets its technical requirements, it is necessary to specify the permitted deviations. Furthermore it is necessary to estimate the consequences of the permitted deviations, which is done via tolerance analysis. During this process the imperfect parts are assembled virtually and the effects of the geometric deviations can be calculated during a variation simulation. Since the tolerance analysis is to enable engineers to identify weak points in an early design stage it is important to know which contribution every single tolerance has on a certain quality-relevant characteristic, to restrict or increase the correct tolerances. In this paper two different approaches are shown and compared to represent the statistical behavior and the strongly connected sensitivity analyses. In particular a newly developed approach, which is based on fuzzy arithmetic, is compared to the established EFAST-method. The exemplary application of both methods and the comparison of the results are illustrated on a case study.

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