Tolerance analysis with the 1D angular dimension chain: Application

A Golay3 multi-mirror telescope (MMT) system is designed in this paper. The fill factor of the Golay3 MMT is derived from the angular resolution of the telescope. An initial configuration is established according to the paraxial optical theory. A three-element aspheric corrector group is designed and placed in the converging light cone to enlarge the field of view (FOV) of the Golay3 MMT. The tolerance analysis for each surface of the Golay3 MMT is conducted using the Monte Carlo method. The design results show the FOV of the Golay3 MMT system can be increased to 1.5° with the insertion of a three-element aspheric corrector group. The results of the tolerance analysis indicate that most tolerances are loose, while some decenter tolerances relating with the aspheric surfaces are relatively tight, but still within an acceptable range.

Download Full-text

NON-NORMAL STATISTICAL TOLERANCE ANALYSIS USING ANALYTICAL CONVOLUTION METHOD

Journal of Advanced Manufacturing Systems ◽

10.1142/s0219686708001218 ◽

2008 ◽

Vol 07 (01) ◽

pp. 127-130 ◽

Cited By ~ 2

Author(s):

S. G. LIU ◽

P. WANG ◽

Z. G. LI

Keyword(s):

Normal Distribution ◽

Closed Loop ◽

Tolerance Analysis ◽

Accurate Method ◽

Probability Density Functions ◽

Triangular Distribution ◽

Normal Distributions ◽

Statistical Tolerance ◽

Statistical Tolerance Analysis ◽

Convolution Method

In statistical tolerance analysis, it is usually assumed that the statistical tolerance is normally distributed. But in practice, there are many non-normal distributions, such as uniform distribution, triangular distribution, etc. The simple way to analyze non-normal distributions is to approximately represent it with normal distribution, but the accuracy is low. Monte-Carlo simulation can analyze non-normal distributions with higher accuracy, but is time consuming. Convolution method is an accurate method to analyze statistical tolerance, but there are few reported works about it because of the difficulty. In this paper, analytical convolution is used to analyze non-normal distribution, and the probability density functions of closed loop component are obtained. Comparing with other methods, convolution method is accurate and faster.

Download Full-text

Process Signature Modeling for Tolerance Analysis

Journal of Computing and Information Science in Engineering ◽

10.1115/1.3402641 ◽

2010 ◽

Vol 10 (2) ◽

Cited By ~ 1

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.

Download Full-text