A frame for a computer aided inspection planning system

Coordinate Measuring Machine (CMM) inspection planning is an activity performed by well-trained operators, but different measurement techniques, using the same data analysis algorithms yield in different measurement results. This is a well-recognized source of uncertainty in coordinate measurement. A CMM, provided with an automatic inspection planning (CAIP) system, permits to implement more accurate and efficient operating procedures and to fit higher quality assurance standards and tighter production timings. In this paper we present a frame of a CAIP system, able to deal with almost all the decisional stages of CMM inspection. Moreover, original approaches have been developed and presented in inspection feature selection, part set -up, probe configuration, and path planning

fea integration in the tolerance analysis using skin model shapes

Abstract Many research works on tolerance analysis have been carried out in the last thirty years. In this paper, a new idea is proposed, aiming to investigate the effect of form error and mechanical behavior of parts on the stack-up result by combining the recent novelties on the tolerance analysis of rigid and flexible bodies. The real parts are simulated considering the non-nominal Skin Model Shape and the mechanical properties in order to simulate the assembly of a realistic case study. A manufacturing signature model to generate the features with geometric deviations and Finite Element Analysis (FEA) are used

Computer-Aided Techniques for Geometry Assurance

Geometry assurance can be described as a number of activities, all contributing to minimize the effect of geometrical variation in a final product. This work aims to introduce a new type of comparison between a computer-aided technique for geometry assurance and some models proposed by the literature. In particular, the aim of this work is to solve, through a computer-aided technique, some case studies that were already solved by different methods of the literature. The different case studies that have been introduced and solved in this paper aim to highlight the potentialities and the limits in using a computer-aided technique for geometry assurance. Because this type of comparison is not present in the literature yet, this work wants to place the emphasis on the fact that till now there is not a unique approach to solve problems of geometry assurance and no approach can be defined as better than another, in terms of results

Robust Design of a Fixture Configuration in the Presence of form Deviations

During machining, the tool path is defined with respect to the workpiece reference frame. The workpiece's boundary surfaces have form deviations, and the geometry and the position of the locators are imperfect. The resulting misalignment produces geometrical errors in the features machined on the workpiece. The main purpose of this work is to investigate how the geometric errors of a machined surface are related to the main sources of the locator errors and to the form deviations of the workpiece. A mathematical framework is presented for an analysis of the relationship among the manufacturing errors, the part form deviations, and the locator errors

3D Tolerance Analysis with Manufacturing Signature and Operating Conditions

The present work shows a method to integrate the manufacturing signature and the operating conditions into a model for 3D tolerance analysis of rigid parts. The paper presents an easy way to manage the actual surfaces due to a manufacturing process and the operating conditions, such as gravity and friction, inside the variational model for a 3D tolerance analysis. The used 3D case study is deliberately simple in order to develop a conceptual demonstration. The obtained results have been compared with those due to a geometrical model that reproduces what happens during assembly. It has been considered as reference case

experimental investigation of hydrothermal ageing on single lap bonded cfrp joints

Abstract Composite materials are increasingly being used in various field of engineering interest over recent decades. As an alternative to fastening, bonding is one of the most promising assembly techniques of composite materials since it allows a uniform distribution of forces, it has a greater ability to dampen vibration and it does not raise any problems of corrosion typical of metal fasteners. Currently the use of composite materials is limited by the incomplete knowledge of their behaviour in an aggressive environment. For example, the factors influencing the durability of the bonded joints are mainly temperature and humidity, but it is usually impossible to predict their effect without performing experiments. In this work is investigated how the hydrothermal ageing can affect the mechanical resistance of CFRP single lap joints. The parameters chosen for the activity consist in two types of adhesives (AF 163-2K film and EA 9309NA paste) and three ageing environments (thermal cycles from -28 °C to 85 °C in air, distilled water and salt water)

evaluation of the spring in of cfrp thin laminates in dependence on process variation

Abstract The cure process of CFRP laminates induces residual stress inside the parts that causes geometrical unconformities. The most important unconformity is the spring-in that means the deviation of the flange-to-flange angle from the design angle. The spring-in value depends on some process parameters, such as the lay-up sequence of the plies, as demonstrated in previous works. The aim of this work is to study the dependence of the spring-in on the deviations in the orientation of the plies due to a hand process. A numerical tool was developed and experimentally tested

Performance Index of Natural Stones-GFRP Hybrid Structures

Natural stone is a material that presents durableness over time and high aesthetic characteristic, but it is brittle and its tensile strength is significantly lower than compressive one: these peculiarities must be taken into account for material usage; in fact, for applications requiring high flexural and tensile strength, as thin sections or long spans, the particular mechanical behavior of the natural stone constitutes an issue to be overcome. A solution to the above mentioned problem is presented in the present paper: a natural stone tile is reinforced by bonding a sandwich structural laminate made of composite materials. In such manner, a double result is obtained: the mechanical strength increment and the and the tile specific weight decrement. In particular, two different types of sandwich structures, made of glass/epoxy laminates and honeycomb or foam core, were bonded to the lower surfaces of marble and granite tiles; then, 3-point bending tests were carried out on specimens extracted from the produced hybrid tiles. A performance index, considering both strength and weight of tiles, was introduced and the comparison with specimens extracted from traditional unreinforced tiles demonstrated that the considered reinforcement increases the structural characteristics of stone tiles up to an order of magnitude

Influence of hydrothermal ageing on single lap bonded CFRP joints

Nowadays adhesive are widely used in structural applications, in particular for assembly composite materials. In fact, this technique allows to obtain a more uniform load in the joint, to realise a joint with an higher specific strength and to avoid drilling parts as in the case of bolted joints. However, the mechanical properties of bonded parts over time are not well understood if they are subjected to a more or less aggressive environment. Generally, the main factors of influence regarding the durability of bonded joints are humidity and temperature, but their effects are not always clear if these two factors act simultaneously. In this work the effect of hydrothermal ageing on the mechanical resistance of single lap bonded CFRP joints has been investigated. In particular two types of adhesives (AF 163-2K film and EA 9309NA paste) and three ageing environments (thermal cycles from -28 °C to 85 °C in air, distilled water and salt water) have been chosen for the activity