Tolerance verification through manufactured part modeling

1988 ◽  
Vol 7 (3) ◽  
pp. 223-232 ◽  
Author(s):  
Faryar Etesami
Author(s):  
Jeremiah Vanderlaan ◽  
Josh Richert ◽  
James Morrison ◽  
Thomas Doyle

We are a group of engineering students, in our first year of undergraduate study. We have been selected from one thousand first year students and have competed and won the PACE competition. All engineers share a common general first year, but we have been accepted into Civil and Mechanical engineering. This project was assigned as the final project in the Design and Graphics course. The project we are tasked with, called the Cornerstone Design Project, is to first dissect a product, discover how it works, dimension each part and create a fully assembled model using CAD software (Solid Edge V20 in our case). As part of discovering how it works we must benchmark it so the device can be compared with competing products. The goal of the project is to develop a full understanding of part modeling and assembly in Solid Edge, learn proper measurement techniques, and learn the process of reverse engineering and product dissection. All of these tasks were stepping stones to help us fully understand how the device, and all its components, work.


Author(s):  
F. Etesami

Abstract One of the routine manual tasks in dimensional inspection is the assembly verification of circular features by mechanical gaging. With the aid of coordinate measuring machines or vision systems, this task can be performed more efficiently through simulation or soft-gaging. A formulation is presented for interpretation of 2D position tolerance specifications. Simulated gages are constructed from datum features as a set of constraint relationships. The measure of perfect-form position-imperfection is determined as the distance between the measured and the nominal feature positions subject to datum constraint requirements. The derived formulation is applied to an example part with a hole-slot datum-priority-frame. This formulation results in a three-variable optimization problem which is solved by an Augmented Lagrange Multipliers technique. The extension of the formulation to 3D is also discussed, but without reference to a specific representation.


Author(s):  
Kaushik Kumar ◽  
Divya Zindani ◽  
J. Paulo Davim
Keyword(s):  

Author(s):  
Joseph Pegna

Abstract In the quest for ever finer levels of technology integration, mechanical linkages reach their precision limits at about 5micrometers per meter of workspace. Beyond this physical limit, all six dimensional degrees of freedom need to be precisely ascertained to account for mechanical imperfections. This paper substantiates Wu’s vision of “precision machines without precision machinery.” A formulation and statistical characterization of position and orientation error propagation in rigid bodies are presented for two extreme models of measurement. It is shown that error distribution is uniquely dependent upon the design of the measurement plan. The theoretical foundations presented were evolved in the course of designing precision machinery. Other potential applications include: fixture design, metrology, and geometric tolerance verification.


2021 ◽  
Author(s):  
Alexander Pasternack ◽  
Ines Langer ◽  
Henning W. Rust ◽  
Uwe Ulbrich

<p>Large cities and urban regions are highly sensitive to impacts caused by extreme events (e.g. heavy rainfall). As problems caused by hazardous atmospheric events are expected to intensify due to the Anthropogenic Climate Change, adequate adaptation planning of urban infrastructure is needed. Planning adaptations not only requires further research on potential impacts under changing climate conditions as a basis, but also a check of the practical feasibility for stakeholders.</p><p>Under the BMBF research program “Urban Climate Under Change” ([UC]²), we relate heavy precipitation events over Berlin to the respective fire brigade operations. Here, the precipitation data are based on temporally high resolved radar data. The fire brigade operation data are available on time and location, but the number of recorded events is small, and their distribution is highly overdispersive compared to a Poisson model. To account for this problem we apply a two part hurdle model with one part modeling the probability of the occurrence of fire brigade operations and one part modeling the actual number of operations given that at least one operation occurs. In the corresponding statistical models the parameters of the distributions are described by additive predictors, which are based on precipitation duration and intensity as well as building density. Based on 10 years of data with a cross validation setup, both the occurrence model and the model for the number of operations significantly outperform the reference climatology for certain areas over Berlin.</p>


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