Nonrigid parts’ specification and inspection methods: notions, challenges, and recent advancements

SAE Technical Paper Series

Desrochers

et al. 2013

Self Cite

Aerospace panels are commonly restrained on complex inspection fixture jigs during the measurement process. Forces used to restrain the parts are also monitored as mandated by thier functional requirements. Given the difficulties in measuring these types of parts, this paper reviews the available fixtureless inspection methods with a focus on the challenges of their implementation, and their aptitude to be used to estimate the profile and the necessary restraining forces of an aerospace panel. To perform this investigation, finite element analysis is used to predict the constrained shape of four (4) simulated free-state aerospace panels, with two different type of boundary conditions, in five scenarios. From those analyses, the importance and limits of current finite element boundary setting methods embedded in fixtureless inspection methods for nonrigid parts are highlighted.

Section: Introductionmentioning

confidence: 99%

Section: By a Forcementioning

confidence: 99%

Aerospace Panels Fixtureless Inspection Methods with Restraining Force Requirements; A Technology Review

Abenhaim

SAE Technical Paper Series

Desrochers

et al. 2013

Self Cite

“…Currently, a flexible workpiece must be constrained or clamped during the measurement process in order to simulate the use state. To that end, expensive and special inspection fixtures need to be designed and manufactured [1]. On the other hand, some inspection stages cannot be fully automated with this conventional approach.…”

Section: Introductionmentioning

confidence: 99%

Performance study of dimensionality reduction methods for metrology of nonrigid mechanical parts

Radvar-Esfahlan

Int. J. Metrol. Qual. Eng.

2013

The geometric measurement of parts using a coordinate measuring machine (CMM) has been generally adapted to the advanced automotive and aerospace industries.However, for the geometric inspection of deformable free-form parts, special inspection fixtures, in combination with CMM's and/or optical data acquisition devices (scanners), are used. As a result, the geometric inspection of flexible parts is a consuming process in terms of time and money. The general procedure to eliminate the use of inspection fixtures based on distance preserving nonlinear dimensionality reduction (NLDR) technique was developed in our previous works. We sought out geometric properties that are invariant to inelastic deformations. In this paper we will only present a systematic comparison of some well-known dimensionality reduction techniques in order to evaluate their accuracy and potential for non-rigid metrology.We will demonstrate that even though these techniques may provide acceptable results through artificial data on certain fields like pattern recognition and machine learning,

“…Abenhaim et al [11] presented a review of the previous researches for the fixtureless inspection of non-rigid parts and proposed a classification of the specification methods used for the GD&T of non-rigid parts under the ASME and ISO standards. In the following, we will introduce the primary methods, based on the simulated displacement approach, developed for the geometric inspection of non-rigid parts without the use of inspection fixtures.…”

Section: Review Of Previous Researchmentioning

confidence: 99%

“…This factor is a relative concept based on the relation between an imposed force and its persuaded displacement [11]. Based on the displacements of parts induced by a reasonable force (50 N) during inspection, the parts are considered rigid/non-rigid (flexible)/extremely non-rigid (see Table 1).…”

Section: Introductionmentioning

confidence: 99%

Fixtureless profile inspection of non-rigid parts using the numerical inspection fixture with improved definition of displacement boundary conditions

Sabri

Int J Adv Manuf Technol

Pham

et al. 2015

Quality control is an important factor for manufacturing companies looking to prosper in an era of globalization, market pressures, and technological advance. The functionality and product quality cannot be guaranteed without this important aspect. Manufactured parts have deviations from their nominal (CAD) shape caused by the manufacturing process. Thus, geometric inspection is a very important element in the quality control of mechanical parts. We have focused here on the profile inspection of non-rigid parts which are widely used in the aeronautic and automotive industries. Non-rigid parts can have different forms in a freestate condition compared with their nominal models due to residual stress and gravity loads. To solve this problem, dedicated inspection fixtures are generally used in industry to compensate for the displacement of such parts for simulating the use state in order to perform geometric inspections. These fixtures and the inspection process are expensive and time-consuming. Our aim is therefore to develop an inspection method which eliminates the need for specialized fixtures by acquiring a point cloud from the displaced part using a contactless measuring system such as optical scanning and comparing it with the CAD model for the identification of deviations. Using a non-rigid registration method and finite element analysis, we will numerically inspect the profile of a non-rigid part. To do so, a simulated displacement is performed using an improved definition of boundary conditions for simulating unfixed parts. In this paper, we will apply an improved method on two industrial non-rigid parts with free-form surfaces simulated with different types of displacement, defect, and measurement noise.