Simulation-Based Tolerance and Assemblability Analyses of Assemblies With Multiple Pin/Hole Floating Mating Conditions

2005 ◽  
Author(s):  
Zhengshu Shen ◽  
Jami J. Shah ◽  
Joseph K. Davidson
Keyword(s):  
Tolerance Analysis ◽  
Virtual Manufacturing ◽  
Product Development Process ◽  
3D Analysis ◽  
Dimensional Problem ◽  
Press Fit ◽  
Simulation Based ◽  
The Difference ◽  
2D And 3D ◽  
Mating Conditions

Development of tolerance analysis methods that are consistent with the ASME and ISO GD&T (geometric dimensioning and tolerancing) standards is a challenging task. Such methods are the basis for creating computer-aided tools for 3D tolerance analysis and assemblability analysis. These tools, along with the others, make it possible to realize virtual manufacturing in order to shorten lead-time and reduce cost in the product development process. Current simulation tools for 3D tolerance analysis and assemblability analysis are far from satisfactory because the underlying variation algorithms are not fully consistent with the GD&T standards. Better algorithms are still to be developed. Towards that goal, this paper proposes an improved simulation-based approach to tolerance and assemblability analyses for assemblies with pin/hole floating mating conditions in mechanical products. A floating pin/hole mating condition is the one where the mating pin should be able to “float” within the mating hole, and thus press-fit is not necessary for the parts to assemble properly. When multiple pin/hole mating pairs are involved in a product, the feasibility of assembly needs to be analyzed. This paper will introduce a more complete method of analyzing assemblability for such assemblies. In most cases, a 3D (3-dimensional) problem can be simplified to 1D (1-dimensional) or 2D (2-dimensional) problem, with the loss of some accuracy. To make a comparison and find out how accurately 1D and 2D analyses can approximate 3D analysis, this paper will provide the variation algorithms for 1D, 2D and 3D simulations. The algorithms developed account not only for bonus/shift tolerances but also for feasibility of assembling. These algorithms are extendable to consider other different GD&T specifications. The assemblability criteria proposed is generally applicable to any assemblies with pin/hole floating mating conditions. Case studies are provided to demonstrate the algorithms developed. The comparison study shows quantitatively the difference in the results from 1D, 2D and 3D simulation based analyses.

A Complete Variation Algorithm for Slot and Tab Features for 3D Simulation-Based Tolerance Analysis

2005 ◽  
Author(s):  
Zhengshu Shen ◽  
Jami J. Shah ◽  
Joseph K. Davidson
Keyword(s):  
Tolerance Analysis ◽  
Virtual Manufacturing ◽  
3D Simulation ◽  
Product Development Process ◽  
Simulation Tools ◽  
Geometric Dimensioning And Tolerancing ◽  
Material Condition ◽  
Tolerance Chart ◽  
Simulation Based ◽  
Mechanical Products

Development of tolerance analysis methods that are consistent with the ASME and ISO GD&T (geometric dimensioning and tolerancing) standards is a challenging task. Such methods are the basis for creating computer-aided tools for 3D tolerance analysis and assemblability analysis. These tools, along with the others, make it possible to realize virtual manufacturing, in order to shorten lead-time and reduce cost in the product development process. Current simulation tools for 3D tolerance analysis and assemblability analysis are far from satisfactory because the underlying variation algorithms are not fully consistent with the GD&T standards. Better algorithms are still to be developed. Towards that goal, this paper proposes a complete algorithm for 3D slot features and tab features (frequently used in mechanical products) for 3D simulation-based tolerance analysis. The algorithms developed account for bonus/shift tolerances (i.e. effects from material condition specifications), and tolerance zone interaction when multiple tolerances are specified on the same feature. A case study is conducted to demonstrate the algorithm developed. The result from this work is compared with that from 1D tolerance chart method. The comparison study shows quantitatively why 1D tolerance chart method, which is popular in industry, is not sufficient for tolerance analysis, which is 3D in nature.

scholarly journals Comparison of 2D and 3D Stability Analyses for Natural Slope

2018 ◽  
Vol 7 (4.35) ◽  
pp. 662
Author(s):  
Erly Bahsan ◽  
Rifani Fakhriyyanti
Keyword(s):  
Three Dimensional ◽  
3D Models ◽  
Soil Parameters ◽  
3D Analysis ◽  
Natural Slope ◽  
Stability Analyses ◽  
The Difference ◽  
2D And 3D ◽  
The Impact ◽  
Natural Slopes

Slope stability analyses are performed mostly as a two-dimensional (2D) section under the assumption of plane strain conditions, without much consideration to the impact of three-dimensional (3D) shapes. For natural slopes that have the complexities of slope surfaces, 3D modeling may also be considered since it can represent the more realistic geometry of the slope. However, previous studies show that the factor of safety (FS) as a result of 3D analyses mostly overestimated the FS from 2D analyses. This may lead to a long discussion on whether the 3D analysis is still applicable for the natural slopes, and could it represent the same results as the 2D analysis. This study was conducted using the finite element method for calculating the 2D and 3D FS of Pasir Muncang natural slope in order to observe differences of FS resulted from both analyses. A comparison of the FS from the 2D and 3D analyses, and also verification of sensitivity on several factors that impact the 2D and 3D models have been performed. The results of this study has indicated that some factors such as soil parameters, contour interval, and mesh coarseness greatly affect the results of the 2D and 3D calculations. Having carefully selected the aforementioned factors as the inputs for calculations, the difference between the FS values of 3D and 2D analyses becomes smaller. The final result of FS for this case study from the 3D analysis was still higher than the one from the 2D analysis, with the ratio of FS from 3D to FS from 2D was 1.44. It can be inferred that the use of 3D analyses needs more accurate data selections compared to the 2D analyses.  

Comparative Analysis of Chosen Tolerance Stackup Methods and Development of an Improved Tolerance Analysis Method

2015 ◽  
Vol 813-814 ◽  
pp. 954-958
Author(s):  
R. Panneer ◽  
A.M. Jackson
Keyword(s):  
Comparative Analysis ◽  
Tolerance Analysis ◽  
Assembly Tolerance ◽  
Simulation Based ◽  
Design And Manufacturing ◽  
Artificial Neural Network Ann ◽  
And Function ◽  
The Cost ◽  
2D And 3D ◽  
Insight Into

The perception of Tolerance Analysis (TA)/Tolerance Stackup is imperative for every Design and Manufacturing Engineer because Tolerance is the criterion that should be compromised between the cost and function of a product. The literatures relevant to 15 methods of TA which are being used to determine Assembly Tolerance from Component Tolerances are collected and critically analyzed to gain an insight into the existing methods. Out of these methods, four major methods viz., Simulation Based Stack-Up Analysis, Second Order Tolerance Analysis, OpTol - Spatial Tolerance Analysis and Tolerance Analysis of 2D and 3D Assemblies are chosen for further study and comparative analysis. Based on the analysis and based on the identified merits and demerits of these methods, a framework for a new TA Method is developed. Based on the developed framework, a new TA Method using Artificial Neural Network (ANN) is developed and trained which can predict the value of Assembly Tolerance for the known Component Tolerances.

Experimental and computed dipole moments in donor–bridge–acceptor systems with p-phenylene and p-carboranediyl bridges

2009 ◽  
Vol 74 (1) ◽  
pp. 131-146 ◽  
Author(s):  
Ladislav Drož ◽  
Mark A. Fox ◽  
Drahomír Hnyk ◽  
Paul J. Low ◽  
J. A. Hugh MacBride ◽  
...  
Keyword(s):  
Dipole Moment ◽  
Dipole Moments ◽  
Electronic Effects ◽  
Electronic Interactions ◽  
Donor And Acceptor ◽  
Homo And Lumo ◽  
Pull Systems ◽  
The Difference ◽  
Experimental Values ◽  
2D And 3D

Dipole moments were measured for a series of substituted benzenes, biphenyls, terphenyls, C-monoaryl- and C,C′-diaryl-p-carboranes. For the donor–bridge–acceptor systems, Me2N–X–NO2, where X is 1,4-phenylene, biphenyl-4,4′-diyl, terphenyl and 1,4-C6H4-p-CB10H10C-1,4-C6H4, the measured interaction dipole moments are 1.36, 0.74, 0.51 and 0.00 D, respectively. The magnitude of the dipole moment reflects the ability of the bridge to transmit electronic effects between donor and acceptor groups. Thus, whilst the 1,4-phenylene bridges allow moderate electronic interactions between the remote groups, the p-carboranediyl unit is less efficient as a conduit for electronic effects. Averaged dipole moments computed at the DFT (B3LYP/6-31G*) level of theory from two distinct molecular conformers are in good agreement with the experimental values. Examination of the calculated electronic structures provides insight into the nature of the interactions between the donor and acceptor moieties through these 2D and 3D aromatic bridges. The most significant cooperative effect of the bridge on the dipole moment occurs in systems where there is some overlap between the HOMO and LUMO orbitals. This orbital overlap criterion may help to define the difference between “push-pull” systems in which electronic effects are mediated by the bridging moiety, and simpler systems in which the bridge acts as an electronically innocent spacer unit and through-space charge transfer/separation is dominant.

Investigation of Mid-Infrared Millimeter Wave Radome with Polycrystalline Magnesium Fluoride

2015 ◽  
Vol 1120-1121 ◽  
pp. 485-489
Author(s):  
Hao Gu ◽  
Xing Yu ◽  
Li Hua He ◽  
Hong Quan Feng
Keyword(s):  
Millimeter Wave ◽  
Moment Method ◽  
Fast Multipole Method ◽  
Magnesium Fluoride ◽  
Fast Multipole ◽  
Mid Infrared ◽  
Simulation Based ◽  
Multipole Method ◽  
The Difference

In this paper, the radome materials suitable for mid-infrared /millimeter wave multimode were introduced, as well as the properties. In comparison with the difference of the radome materials, the polycrystalline magnesium fluoride was promising for the radome of mid-infrared /millimeter wave multimode. Furthermore, the millimeter wave transparent properties of polycrystalline magnesium fluoride were studied by the simulation based on moment method and multilevel fast multipole method.

Applications of Mating Conditions in Assembly Sequence Planning Task

1998 ◽  
Author(s):  
Pongsak Dulyapraphant ◽  
Tulga Ozsoy
Keyword(s):  
Degrees Of Freedom ◽  
Tolerance Analysis ◽  
Assembly Sequence Planning ◽  
Assembly Model ◽  
Assembly Sequence ◽  
Kinematics Analysis ◽  
Sequence Planning ◽  
Planning Task ◽  
Intuitive Interface ◽  
Mating Conditions

Abstract Because of their intuitive interface, mating conditions have been prevalently used in assembly modelling. Besides their use for modelling purposes, other type of information, such as spatial relationships between parts and local degrees of freedom, can be directly derived from mating conditions. This information in turn can be used in various engineering analysis applications, such as kinematics analysis or automatic tolerance chain generation for tolerance analysis. In this paper, application of mating conditions in an assembly sequence-planning task is investigated. The proposed approach mainly engages the mating information represented in the CAD assembly model to automatically generate sequence plans based on the minimization of the number of assembly directions.

Process Capability Based Tolerance Allocation in Pneumatic Percussive Riveting

2020 ◽  
Author(s):  
Hua Wang ◽  
Jialei Zhang ◽  
Junyang Yu
Keyword(s):  
High Efficiency ◽  
Load Transfer ◽  
Process Capability ◽  
Tolerance Analysis ◽  
Tolerance Allocation ◽  
Hole Drilling ◽  
Case Method ◽  
Pneumatic Hammer ◽  
Worst Case ◽  
Mating Conditions

Abstract Pneumatic percussive riveting is an important way to join the sheet metals. In order to ensure the load transfer and the fatigue performance of riveted joint, the interference of the rivet/hole is strictly specified. The interference of the rivet/hole is highly correlated with the process capability of the pneumatic hammer and the diameter of the pre-hole. It is a critical step to choose the appropriate pneumatic hammer to ensure the interference requirements. Energy per blow of the pneumatic hammer is a proclaimed parameter from the riveting hammer manufacturer. It is difficult for the designer to choose the riveting hammer in practical riveting scheme based on energy per blow. Tolerance analysis is an efficient way to model the manufacturing variation and implement process control. This paper presents the tolerance allocation of the pneumatic percussive riveting based on the process capability of the pneumatic hammer. In order to obtain the designed interferences of the rivet/hole, a tolerance chain is built with the process capability of the pneumatic hammer, the diameter of the pre-hole and the diameter of the rivet shank. The process capability of the pneumatic hammer is represented with the interferences of the rivet/hole after riveting. It is an intuitive parameter for the designer to choose the riveting hammer in practical riveting scheme. The process capability of the pneumatic hammer is obtained from the designed riveting experiments with the pneumatic percussive riveting platform. The diameter of the pre-hole affects the interference of the rivet/hole also. The tolerance for manual hole-drilling should be determined to assure the interference requirements and high drilling operation efficiency simultaneously. The variation of the pre-hole is obtained from the manual drilling experiments and diameter measurements. Different hole-drilling results in different mating conditions between the pre-hole and the rivet. The fit conditions of different pre-holes are modeled and the final interferences after riveting are analyzed. Worst case method and statistical analysis method are two common methods for tolerance analysis. For the manual hole-drilling and the pneumatic percussive riveting, worst case method is employed to analyze the constructed tolerance chain in order to accomplish the interferences of the rivet/hole. The different analyzed dimensions, rivet-hole clearances and pre-hole drilling variation, are investigated respectively. The reported work enhances the understanding of the tolerance allocation for the pneumatic percussive riveting. The interference based process capability of the pneumatic hammer provides good reference for pneumatic hammer choosing in riveting scheme. The reported tolerance chain of the interference could be used for the tolerance determination of manual hole-drilling with good quality and high efficiency.

scholarly journals Application of a Perception Neuron® System in Simulation-Based Surgical Training

2019 ◽  
Vol 8 (1) ◽  
pp. 124 ◽  
Author(s):  
Hyun Kim ◽  
Nhayoung Hong ◽  
Myungjoon Kim ◽  
Sang Yoon ◽  
Hyeong Yu ◽  
...  
Keyword(s):  
Motion Capture ◽  
Da Vinci ◽  
Training Model ◽  
Dominant Hand ◽  
Simulation Methods ◽  
Surgical Trainees ◽  
Simulation Based ◽  
Da Vinci Skills Simulator ◽  
The Difference ◽  
The Relationship

While multiple studies show that simulation methods help in educating surgical trainees, few studies have focused on developing systems that help trainees to adopt the most effective body motions. This is the first study to use a Perception Neuron® system to evaluate the relationship between body motions and simulation scores. Ten medical students participated in this study. All completed two standard tasks with da Vinci Skills Simulator (dVSS) and five standard tasks with thyroidectomy training model. This was repeated. Thyroidectomy training was conducted while participants wore a perception neuron. Motion capture (MC) score that indicated how long the tasks took to complete and each participant’s economy-of-motion that was used was calculated. Correlations between the three scores were assessed by Pearson’s correlation analyses. The 20 trials were categorized as low, moderate, and high overall-proficiency by summing the training model, dVSS, and MC scores. The difference between the low and high overall-proficiency trials in terms of economy-of-motion of the left or right hand was assessed by two-tailed t-test. Relative to cycle 1, the training model, dVSS, and MC scores all increased significantly in cycle 2. Three scores correlated significantly with each other. Six, eight, and six trials were classified as low, moderate, and high overall-proficiency, respectively. Low- and high-scoring trials differed significantly in terms of right (dominant) hand economy-of-motion (675.2 mm and 369.4 mm, respectively) (p = 0.043). Perception Neuron® system can be applied to simulation-based training of surgical trainees. The motion analysis score is related to the traditional scoring system.

Cross-sectional Cathodoluminescence Study in Ga-polar and N-polar GaN Epilayers

2000 ◽  
Vol 639 ◽  
Author(s):  
X. L. Du ◽  
D. H. Lim ◽  
K. Xu ◽  
B. L. Liu ◽  
A. W. Jia ◽  
...  
Keyword(s):  
Defect Formation ◽  
Growth Mode ◽  
Ion Scattering ◽  
Island Growth ◽  
Cross Sectional ◽  
Ion Scattering Spectroscopy ◽  
Low Pressure Mocvd ◽  
The Difference ◽  
Film Substrate ◽  
2D And 3D

ABSTRACTHighly spatial resolved cross-sectional cathodoluminescence (CL) has been used to study the difference in the defect-formation and growth-mechanism between Ga-polar and N-polar GaN epitaxial layers. These epilayers were grown on sapphire substrates by low pressure MOCVD. Their polarities were controlled by the sapphire nitridation and the trimethylaluminum (TMAl) pre-flow just before the conventional two-step growth, and were confirmed with the coaxial impact collision ion scattering spectroscopy (CAICISS). For the Ga-polar GaN epilayers, cross-sectional CL images show distinct two layers, the upper layer with dark lines along c-direction and the layer close to the film-substrate interface with pyramidal dark regions. These two layers correspond to quasi 2D and 3D growth mode respectively. Whereas, the crosssectional CL image taken on the N-polar epilayers is predominated with small dark spots which were randomly distributed throughout the whole GaN epilayer, illustrating the predominant island growth mode in N-polar films.

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