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.

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.

Assembly Tolerance Analysis for Injection Molded Modular, Polymer Microfluidic Devices

2008 ◽  
Author(s):  
Byoung Hee You ◽  
Daniel S. Park ◽  
P.-C. Chen ◽  
Sudheer D. Rani ◽  
Dimitris E. Nikitopoulos ◽  
...  
Keyword(s):  
Tolerance Analysis ◽  
Microfluidic Devices ◽  
Cost Effective ◽  
Assembly Tolerance ◽  
Assembly Accuracy ◽  
Assembly Features ◽  
Injection Molded ◽  
Assembly Feature ◽  
Tolerance Model ◽  
Vertical Gap

Validation of a tolerance analysis for the assembly of modular, polymer microfluidic devices was performed using simulations and experiments. A set of three v-groove and hemisphere-tipped post joints was adopted as a model assembly features. An assembly function with assembly feature dimensions and locations was modeled kinematically. Monte Carlo methods were applied to the assembly function to simulate variation of the assembly. Assembly accuracy was evaluated assuming that the variations of the assembly features were randomly distributed. The estimated mismatches were 118 ± 30 μm and 19 ± 13 μm along the X- and Y-axes, respectively. The estimated vertical gap between the modules at the alignment standards along the X- and Y-axes 312 ± 37 μm and 313 ± 37 μm, compared to the designed value of 287 μm. To validate the tolerance model, two micromilled brass mold inserts containing the assembly features and alignment standards were used to double-sided injection mold polymer parts. The accuracy of the assembly of the modular microdevices was estimated by measuring the mismatch and vertical gaps between alignment standards on each axis. The measured lateral mismatches were 103 ± 6 μm and 16 ± 4 μm along the X- and Y-axes, respectively. The vertical gaps measured for the assemblies were 316 ± 4 μm and 296 ± 9 μm at the X- and Y-axes, compared to the designed distance of 287 μm. Simulation and experimental results were in accordance with each other. The models can be used to predict the assembly tolerance of polymer microfluidic devices and have significant potential for enabling the realization of cost-effective mass production of modular instruments.

A novel method for single and multiple damage detection in beams using relative natural frequency changes

2019 ◽  
Vol 132 ◽  
pp. 335-352 ◽  
Author(s):  
Ganggang Sha ◽  
Maciej Radzieński ◽  
Maosen Cao ◽  
Wiesław Ostachowicz
Keyword(s):  
Damage Detection ◽  
Natural Frequency ◽  
Novel Method ◽  
Frequency Changes

scholarly journals A novel method for the analytical solution of fractional Zakharov–Kuznetsov equations

2019 ◽  
Vol 2019 (1) ◽  
Author(s):  
Rasool Shah ◽  
Hassan Khan ◽  
Dumitru Baleanu ◽  
Poom Kumam ◽  
Muhammad Arif
Keyword(s):  
Present Method ◽  
Decomposition Method ◽  
Fractional Derivatives ◽  
Adomian Decomposition Method ◽  
Current Method ◽  
Analytical Technique ◽  
Suggested Technique ◽  
Adomian Decomposition ◽  
Novel Method ◽  
The Given

AbstractIn this article, an efficient analytical technique, called Laplace–Adomian decomposition method, is used to obtain the solution of fractional Zakharov– Kuznetsov equations. The fractional derivatives are described in terms of Caputo sense. The solution of the suggested technique is represented in a series form of Adomian components, which is convergent to the exact solution of the given problems. Furthermore, the results of the present method have shown close relations with the exact approaches of the investigated problems. Illustrative examples are discussed, showing the validity of the current method. The attractive and straightforward procedure of the present method suggests that this method can easily be extended for the solutions of other nonlinear fractional-order partial differential equations.

scholarly journals An evolutionary approach to the vehicle route planning in e-waste mobile collection on demand

2021 ◽  
Vol 25 (8) ◽  
pp. 6665-6680
Author(s):  
Krzysztof Szwarc ◽  
Piotr Nowakowski ◽  
Urszula Boryczka
Keyword(s):  
Tabu Search ◽  
Quality Evaluation ◽  
Memetic Algorithm ◽  
Route Planning ◽  
Memetic Algorithms ◽  
Approximate Methods ◽  
On Demand ◽  
Suboptimal Solutions ◽  
Novel Method ◽  
The Given

AbstractThe article discusses the utilitarian problem of the mobile collection of waste electrical and electronic equipment. Due to its $$\mathcal {NP}$$ NP -hard nature, implies the application of approximate methods to discover suboptimal solutions in an acceptable time. The paper presents the proposal of a novel method of designing the Evolutionary and Memetic Algorithms, which determine favorable route plans. The recommended methods are determined using quality evaluation indicators for the techniques applied herein, subject to the limits characterizing the given company. The proposed Memetic Algorithm with Tabu Search provides much better results than the metaheuristics described in the available literature.

scholarly journals Surface Fitting for non-Grid Data from in-Situ Measuring Systems of Aero-engine Blade

2020 ◽  
Vol 206 ◽  
pp. 03023
Author(s):  
Qing Mao ◽  
Sen Wang ◽  
Shugui Liu
Keyword(s):  
Dynamic Performance ◽  
Surface Fitting ◽  
Data Conversion ◽  
Machining Accuracy ◽  
Nurbs Surface ◽  
Grid Data ◽  
Measuring Systems ◽  
Aero Engine ◽  
Engine Blade

High machining accuracy of aero-engine blade largely determines the carrying capacity, endurance, acceleration and the dynamic performance of the aero-engine, so a reliable machining error inspection and evaluation technique is imperative. In order to give a reliable error evaluation, the non- uniform rational B-spline (NURBS) technique is adopted to reconstruct the surface within a specified accuracy. Usually, data points measured from aero-engine blade are non-grid data in situ measuring systems. To overcome the difficulty of NURBS surface fitting from non-grid data, a new method based on data conversion is proposed, in which chord length parameterization and uniform parameter sampling are combined together to realize the data convertation, and subsequently hierarchical fitting strategy is applied to finish the NURBS surface reconstruction. The way proposed for data conversion is easy to realize, and by which gemetrical features of original measured data are also reserved well, which make the whole method outstanding in low time cost. Experimental results show that the method is fast, effective. The source code has been implemented in VC++, while the resulting pictures are constructed in Matlab with the obtained control points, knot vectors, and the orders.

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.

scholarly journals Hierarchical Classification Based on Label Distribution Learning

2019 ◽  
Vol 33 ◽  
pp. 5533-5540 ◽  
Author(s):  
Changdong Xu ◽  
Xin Geng
Keyword(s):  
Hierarchical Classification ◽  
Experimental Results ◽  
Challenging Problem ◽  
Training Set ◽  
True Label ◽  
Major Bottleneck ◽  
Novel Method ◽  
Class Labels ◽  
Label Distribution ◽  
The Given

Hierarchical classification is a challenging problem where the class labels are organized in a predefined hierarchy. One primary challenge in hierarchical classification is the small training set issue of the local module. The local classifiers in the previous hierarchical classification approaches are prone to over-fitting, which becomes a major bottleneck of hierarchical classification. Fortunately, the labels in the local module are correlated, and the siblings of the true label can provide additional supervision information for the instance. This paper proposes a novel method to deal with the small training set issue. The key idea of the method is to represent the correlation among the labels by the label distribution. It generates a label distribution that contains the supervision information of each label for the given instance, and then learns a mapping from the instance to the label distribution. Experimental results on several hierarchical classification datasets show that our method significantly outperforms other state-of-theart hierarchical classification approaches.

The Optimization of Thermocouple Galvanometer System Dynamics When Measuring Temperature Transients

1973 ◽  
Vol 6 (9) ◽  
pp. 384-388
Author(s):  
W. H. McKenzie ◽  
A. H. Richards
Keyword(s):  
System Dynamics ◽  
Natural Frequency ◽  
Time Constant ◽  
Exponential Type ◽  
Natural Frequencies ◽  
Low Voltage ◽  
Damping Ratio ◽  
Dynamic Performance ◽  
Ultra Violet ◽  
Dimensional Parameter

When using thermocouples directly connected to ultra-violet galvanometers for recording temperature transients, the low-voltage outputs necessitate the use of galvanometers with low natural frequencies. This puts a limitation on the overall dynamic performance. In a particular application, the user has to select the damping resistor for the galvanometer and the work describes how this is done so that the system is optimised for minimum integrated errors during a transient. The transient considered was of an exponential type which occurs frequently in practice and it is shown that the correct damping ratio and hence damping resistor for the galvanometer depends upon the non-dimensional parameter defined by the product of the natural frequency of the galvanometer and the time constant of the exponential. The results show that the usual value of damping ratio of 0·64 based on minimum sinusoidal distortion has to be modified for best dynamic performance. However, if the non-dimensional parameter is sufficiently large, higher values of damping can be used, which produce a large trace with acceptably small errors.

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.

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