A comprehensive study of three dimensional tolerance analysis methods

This paper reviews four major methods for tolerance analysis and compares them. The methods discussed are: (1) one-dimensional tolerance charts; (2) parametric tolerance analysis, especially parametric analysis based on the Monte Carlo simulation; (3) vector loop (or kinematic) based tolerance analysis; and (4) ASU Tolerance-Map® (T-Map®) (Patent pending; nonprovisional patent application number: 09/507, 542 (2002)) based tolerance analysis. Tolerance charts deal with worst-case tolerance analysis in one direction at a time and ignore possible contributions from the other directions. Manual charting is tedious and error prone, hence, attempts have been made for automation. The parametric approach to tolerance analysis is based on parametric constraint solving; its inherent drawback is that the accuracy of the simulation results are dependent on the user-defined modeling scheme, and its inability to incorporate all Y14.5 rules. The vector loop method uses kinematic joints to model assembly constraints. It is also not fully consistent with Y14.5 standard. The ASU T-Map® based tolerance analysis method can model geometric tolerances and their interaction in truly three-dimensional context. It is completely consistent with Y14.5 standard but its use by designers may be quite challenging. The T-Map® based tolerance analysis method is still under development. Despite the shortcomings of each of these tolerance analysis methods, each may be used to provide reasonable results under certain circumstances. Through a comprehensive comparison of these methods, this paper will offer some recommendations for selecting the best method to use for a given tolerance accumulation problem.

Download Full-text

Three-dimensional tolerance analysis of discrete surface structures based on the torsor cluster model

Assembly Automation ◽

10.1108/aa-11-2019-0205 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Chuanyuan Zhou ◽

Zhenyu Liu ◽

Chan Qiu ◽

Jianrong Tan

Keyword(s):

Mathematical Model ◽

Cluster Model ◽

Three Dimensional ◽

Tolerance Analysis ◽

Analysis Method ◽

Discrete Elements ◽

Content Type ◽

Dimensional Tolerance ◽

Discrete Surfaces ◽

Discrete Surface

Purpose The purpose of this paper is to propose a novel mathematical model to present the three-dimensional tolerance of a discrete surface and to carry out an approach to analyze the tolerance of an assembly with a discrete surface structure. A discrete surface is a special structure of a large surface base with several discrete elements mounted on it, one, which is widely used in complex electromechanical products. Design/methodology/approach The geometric features of discrete surfaces are separated and characterized by small displacement torsors according to the spatial relationship of discrete elements. The torsor cluster model is established to characterize the integral feature variation of a discrete surface by integrating the torsor model. The influence and accumulation of the assembly tolerance of a discrete surface are determined by statistical tolerance analysis based on the unified Jacobian-Torsor method. Findings The effectiveness and superiority of the proposed model in comprehensive tolerance characterization of discrete surfaces are successfully demonstrated by a case study of a phased array antenna. The tolerance is evidently and intuitively computed and expressed based on the torsor cluster model. Research limitations/implications The tolerance analysis method proposed requires much time and high computing performance for the calculation of the statistical simulation. Practical implications The torsor cluster model achieves the three-dimensional tolerance representation of the discrete surface. The tolerance analysis method based on this model predicts the accumulation of the tolerance of components before their physical assembly. Originality/value This paper proposes the torsor cluster as a novel mathematical model to interpret the tolerance of a discrete surface.

Download Full-text

A quasi-Monte Carlo statistical three-dimensional tolerance analysis method of products based on edge sampling

Assembly Automation ◽

10.1108/aa-09-2020-0144 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Chuanyuan Zhou ◽

Zhenyu Liu ◽

Chan Qiu ◽

Jianrong Tan

Keyword(s):

Monte Carlo ◽

Three Dimensional ◽

Sampling Strategy ◽

Tolerance Analysis ◽

Analysis Method ◽

Content Type ◽

Dimensional Tolerance ◽

Quasi Monte Carlo ◽

Edge Sampling ◽

The Impact

Purpose The conventional statistical method of three-dimensional tolerance analysis requires numerous pseudo-random numbers and consumes enormous computations to increase the calculation accuracy, such as the Monte Carlo simulation. The purpose of this paper is to propose a novel method to overcome the problems. Design/methodology/approach With the combination of the quasi-Monte Carlo method and the unified Jacobian-torsor model, this paper proposes a three-dimensional tolerance analysis method based on edge sampling. By setting reasonable evaluation criteria, the sequence numbers representing relatively smaller deviations are excluded and the remaining numbers are selected and kept which represent deviations approximate to and still comply with the tolerance requirements. Findings The case study illustrates the effectiveness and superiority of the proposed method in that it can reduce the sample size, diminish the computations, predict wider tolerance ranges and improve the accuracy of three-dimensional tolerance of precision assembly simultaneously. Research limitations/implications The proposed method may be applied only when the dimensional and geometric tolerances are interpreted in the three-dimensional tolerance representation model. Practical implications The proposed tolerance analysis method can evaluate the impact of manufacturing errors on the product structure quantitatively and provide a theoretical basis for structural design, process planning and manufacture inspection. Originality/value The paper is original in proposing edge sampling as a sampling strategy to generating deviation numbers in tolerance analysis.

Download Full-text

The Influence of Blade Wakes on the Performance of Interturbine Diffusers

Journal of Turbomachinery ◽

10.1115/1.2836649 ◽

1996 ◽

Vol 118 (2) ◽

pp. 347-352 ◽

Cited By ~ 19

Author(s):

R. G. Dominy ◽

D. A. Kirkham

Keyword(s):

Performance Modeling ◽

Three Dimensional ◽

Secondary Flows ◽

Two Dimensional ◽

Correct Performance ◽

Analysis Methods ◽

Flow Factor ◽

The Mean ◽

Lp Turbine

Interturbine diffusers provide continuity between HP and LP turbines while diffusing the flow upstream of the LP turbine. Increasing the mean turbine diameter offers the potential advantage of reducing the flow factor in the following stages, leading to increased efficiency. The flows associated with these interturbine diffusers differ from those in simple annular diffusers both as a consequence of their high-curvature S-shaped geometry and of the presence of wakes created by the upstream turbine. It is shown that even the simplest two-dimensional wakes result in significantly modified flows through such ducts. These introduce strong secondary flows demonstrating that fully three-dimensional, viscous analysis methods are essential for correct performance modeling.

Download Full-text

Three dimensional tolerance investigations on assembly of ITER vacuum vessel

2009 23rd IEEE/NPSS Symposium on Fusion Engineering ◽

10.1109/fusion.2009.5226502 ◽

2009 ◽

Cited By ~ 1

Author(s):

J. Reich ◽

J-J. Cordier ◽

B. Macklin ◽

B. Giraud ◽

D. Wilson ◽

...

Keyword(s):

Three Dimensional ◽

Vacuum Vessel ◽

Dimensional Tolerance

Download Full-text

A review on the role of 3D printing in the fight against COVID-19: safety and challenges

Rapid Prototyping Journal ◽

10.1108/rpj-08-2020-0198 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Sapam Ningthemba Singh ◽

Vavilada Satya Swamy Venkatesh ◽

Ashish Bhalchandra Deoghare

Keyword(s):

Supply Chain ◽

3D Printing ◽

Three Dimensional ◽

Content Type ◽

Medical Supplies ◽

Future Challenges ◽

Safety And Reliability ◽

3D Printed ◽

Comprehensive Study

Purpose During the COVID-19 pandemic, the three-dimensional (3D) printing community is actively participating to address the supply chain gap of essential medical supplies such as face masks, face shields, door adapters, test swabs and ventilator valves. This paper aims to present a comprehensive study on the role of 3D printing during the coronavirus (COVID-19) pandemic, its safety and its challenges. Design/methodology/approach This review paper focuses on the applications of 3D printing in the fight against COVID-19 along with the safety and challenges associated with 3D printing to fight COVID-19. The literature presented in this paper is collected from the journal indexing engines including Scopus, Google Scholar, ResearchGate, PubMed, Web of Science, etc. The main keywords used for searches were 3D printing COVID-19, Safety of 3D printed parts, Sustainability of 3D printing, etc. Further possible iterations of the keywords were used to collect the literature. Findings The applications of 3D printing in the fight against COVID-19 are 3D printed face masks, shields, ventilator valves, test swabs, drug deliveries and hands-free door adapters. As most of these measures are implemented hastily, the safety and reliability of these parts often lacked approval. The safety concerns include the safety of the printed parts, operators and secondary personnel such as the workers in material preparation and transportation. The future challenges include sustainability of the process, long term supply chain, intellectual property and royalty-free models, etc. Originality/value This paper presents a comprehensive study on the applications of 3D printing in the fight against COVID-19 with emphasis on the safety and challenges in it.

Download Full-text