Physics-driven Shape Variation Modelling at Early Design Stage (original) (raw)
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Procedia CIRP, 2018
In today's business environment, the trend towards more product variety and customization is unbroken. Due to this development, the need of agile and reconfigurable production systems emerged to cope with various products and product families. To design and optimize production systems as well as to choose the optimal product matches, product analysis methods are needed. Indeed, most of the known methods aim to analyze a product or one product family on the physical level. Different product families, however, may differ largely in terms of the number and nature of components. This fact impedes an efficient comparison and choice of appropriate product family combinations for the production system. A new methodology is proposed to analyze existing products in view of their functional and physical architecture. The aim is to cluster these products in new assembly oriented product families for the optimization of existing assembly lines and the creation of future reconfigurable assembly systems. Based on Datum Flow Chain, the physical structure of the products is analyzed. Functional subassemblies are identified, and a functional analysis is performed. Moreover, a hybrid functional and physical architecture graph (HyFPAG) is the output which depicts the similarity between product families by providing design support to both, production system planners and product designers. An illustrative example of a nail-clipper is used to explain the proposed methodology. An industrial case study on two product families of steering columns of thyssenkrupp Presta France is then carried out to give a first industrial evaluation of the proposed approach.
Towards improvement of geometrical quality for manual assembly parts
2017
Geometrical variation affects all mass-produced products. This variation will lead to deviations from the nominal design of the product both in terms of aesthetical and functional properties. Geometrical variation originates either from the manufacturing of the parts or from the assembly process. In order to minimize the effect of variation robust design principles are often used. In early product development the majority of the properties in the system solutions are fixed and to change these later in the product development will be costly. In order to verify the system solution (locating scheme and tolerances), different simulation techniques are used to predict the behavior of the product. This is done using virtual tools, for example Computer Aided Tolerancing (CAT). In order to gain confidence for such tools it is very important that the simulation results are accurate and that they capture all factors that influence the product. In this thesis the focus has been on geometry as...
Modeling of 2D and 3D assemblies taking into account form errors of plane surfaces
2009
The tolerancing process links the virtual and the real worlds. From the former, tolerances define a variational geometrical language (geometric parameters). From the latter, there are values limiting those parameters. The beginning of a tolerancing process is in this duality. As high precisions assemblies cannot be analyzed with the assumption that form errors are negligible, we propose to apply this process to assemblies with form errors through a new way allowing to parameterize forms and solve their assemblies. The assembly process is calculated through a method allowing to solve the 3D assemblies of pairs of surfaces having form errors using a static equilibrium. We have built a geometrical model based on the modal shapes of the ideal surface. We compute the completely deterministic contact points between this pair of shapes according to a given assembly process. The solution gives an accurate evaluation of the assembly performance. Then we compare the results with or without taking into account form errors. When we analyze a batch of assemblies, the problem is to compute the Non-Conformity Rate (NCR) of a pilot production according to the functional requirements. We input probable errors of surfaces (position, orientation, and form) in our calculus and we evaluate the quality of the results compared to the functional requirements. The pilot production can then be validated or not.
Parametric effect analysis of free-form shape error during sheet metal forming
2017
Compliant sheet metal parts or free-form shaped parts are widely used for automotive bodies, aerospace fuselage/wing or home appliances. Intrinsic flexibility of sheet metal along with forming process variability throws a number of challenges to produce geometrically conforming parts. Additionally, emerging optical non-contact metrology scanners offer to capture entire part geometric quality information which enables virtual design and manufacturing at early stage. This paper focuses on developing a generic functional data analysis based approach to quantify geometric error/shape error which are generated by process or material parameters (such as material thickness, stamping speed and blank holding force) during sheet metal forming process. The research methodology involves: (i) experimental investigation by varying the design parameters; (ii) capturing entire surface based shape error information (i.e. high density cloud-of-points, CoPs) by using optical scanner; (iii) functional ...
Integration of tolerances in the mechanical product process: Assembly with defects modelling
2013
a. Mechanical Engineering Laboratory, National Engineering School of Monastir, Monastir University, Av. Ibn Eljazzar, 5019 Monastir, Tunisia. a, b. LIPPS, ETS, 1100, Notre-Dame Ouest, Montreal, H3C1K3, Quebec, Canada. Borhen.louhichi@etsmtl.ca, abdelmajid.benamara@enim.rnu.tn Abstract: The part and assembly requirements are specified by the tolerances. In the Digital Mock-Up (DMU), the product is designed on nominal configuration and the tolerances are formally allocated to the CAD model. Thus, the impacts of the tolerance stack-up on the advanced phase of the product design (Dynamic computation, F.E Analysis...) are neglected. The DMU improvement requires the tolerance integration in CAD model. A developed model allows obtaining the components with defects according to dimensional and geometrical tolerances specified in the nominal model. In CAD model, the assembly of the components with dimensional and geometrical defects requires the updating of the assembly mating constraints. T...
Compensation for Geometrical Deviations in Additive Manufacturing
Technologies, 2019
The design of additive manufacturing processes, especially for batch production in industrial practice, is of high importance for the propagation of new additive manufacturing technology. Manual redesign procedures of the additive manufactured parts based on discrete measurement data or numerical meshes are error prone and hardly automatable. To achieve the required final accuracy of the parts, often, various iterations are necessary. To address these issues, a data-driven geometrical compensation approach is proposed that adapts concepts from forming technology. The measurement information of a first calibration cycle of manufactured parts is the basis of the approach. Through non-rigid transformations of the part geometry, a new shape for the subsequent additive manufacturing process was derived in a systematic way. Based on a purely geometrical approach, the systematic portion of part deviations can be compensated. The proposed concept is presented first and was applied to a samp...
Journal of Manufacturing Systems, 2008
Rigid and compliant models have been developed in parallel in the literature for variation analysis of different assembly processes. For a complex assembly system, it is desirable to balance accuracy and simplicity by introducing a rigid-compliant hybrid model. This paper develops a new method aimed at providing an interface between rigid and compliant assembly models. Part geometric errors (PGE) and rigid body kinematics stackup error (RE) are simulated and integrated in rigid assembly processes. A covariance matrix of PGE and RE is then constructed, providing input to subsequent compliant assembly models. Algorithms are developed (1) to predict RE by using the stream of variation (SOVA) model; (2) to simulate PGE based on statistical modal analysis (SMA) and specified tolerances; and (3) to integrate RE and PGE in rigid assembly processes for covariance matrix construction. This is an initial step toward the development of a rigid-compliant hybrid assembly model for variation analysis in multistation manufacturing systems (MMS).
Assembly sequence influence on geometric deviations propagation of compliant parts
International Journal of Production Research, 2011
This paper presents a non-rigid part variation simulation method for fulfilling functionnal requirements on compliant assemblies. This method is based on the propagation of different geometrical deviations (manufacturing and assembly process defects) using the Method of Influence Coefficient. Tolerance analysis of compliant assemblies is also achieved very early in the design stage. As a consequence, designers and manufacturing engineers can efficiently analyse the assembly design principles both in terms of installed stresses and geometric variation clearance. They can also set optimised' sequences that enable to get rid of geometric variations.
Computer-Aided Design
Geometric and dimensional variations in objects are caused by inevitable uncertainties in manufacturing processes and often lead to product quality issues. Failing to model the effect object shape errors, i.e., geometric and dimensional errors of parts, early during design phase inhibits the ability to predict such quality issues; consequently leading to expensive design changes after freezing of design. State-of-Art methodologies for modelling and simulating object shape error have limited defect fidelity, data versatility, and designer centricity that prevent their effective application during early design phase. Overcoming these limitations a novel Morphing Gaussian Random Field (MGRF) methodology for object shape error modelling and simulation is presented in this paper. The MGRF methodology has (i) high defect fidelity and is capable of simulating various part defects including local and global deformations, and technological patterns; (ii) high data versatility and can effectively simulate non-ideal parts under the constraint of limited data availability and can utilise historical non-ideal part data of similar parts; (iii) designer centric capabilities such as performing 'what if?' analysis of practically relevant defects, and model parameters that are physically meaningful; and (iv) capability to generate non-ideal parts conforming to statistical form tolerance specification without additional modelling effort. The aforementioned capabilities enable MGRF methodology to accurately model and simulate the effect of object shape variations on product quality during the early design phase. This is achieved by first, modelling the spatial correlation in the deviations of the part from its design nominal using Gaussian Random Field and then, utilising the modelled spatial correlations to generate non-ideal parts by conditional simulations. Practical applications of developed MGRF methodology and its advantages are demonstrated using sport-utility-vehicle door parts.