Influence of manufacturing tolerance on aircraft direct operating cost (DOC)

Curran, Richard; Kundu, Ajoy Kumar; Raghunathan, Srinivasan; Eakin, D.E.; McFadden, Richard H.

doi:10.1016/s0924-0136(03)00073-6

Cited by 20 publications

(17 citation statements)

References 19 publications

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“…Even fewer techniques account for the concurrent effect of tolerance on the performance, quality and manufacturing cost. Curran et al 5 investigated the influence of tolerance on the direction operating cost (DOC) of an aircraft by extrapolating the results from the study performed on engine nacelle structure, and showed that relatively small relaxation in the tolerances resulted in reduced costs of production that lowered the DOC. Furthermore, Kundu and Curran 6 proposed a concept of global 'Design for Customer' approach that conjoins various individual design for customer approaches, such as 'Design for Performance', 'Design for Quality', 'Design for Cost', 'Design for Safety" to allocate the manufacturing tolerances.…”

Section: Fig 2 Cross-sectional View Of a Plate With Fastener Hole Atmentioning

confidence: 99%

Aircraft Tolerance Optimization Considering Quality, Manufacturing & Performance

Bhachu

Waycaster

Haftka

et al. 2013

54th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference

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Manufacturing tolerance allocation is a design challenge that plays an important role in balancing the cost and weight objectives for an aircraft. The purpose of this paper is to explore an approach to optimize manufacturing tolerances by combining the individual objectives of the quality, manufacturing and design teams. We illustrate this approach on a fatigue critical lap joint structure that consists of a wing spar and a strap that must tolerate the manufacturing errors associated with location and size of the fastener holes. These errors are modeled with industrial data collected from the wing assemblies of a business jet. A cost model is formulated in terms of the quality cost, manufacturing cost and performance cost, and optimal tolerance is found by minimizing the sum of these costs (i.e. total cost). It was found that as the aircraft size grows bigger the weight increases more quickly than the quality cost requiring the use of tighter tolerance. A sensitivity analysis is also performed to identify the input variables that have significant impact on the optimal tolerance and corresponding total cost. Nomenclatured = Fastener hole diameter e = Fastener edge distance h = Spar height L = Spar length nf = Total no. of fasteners nf-pf = Total no. of fasteners per foot PQN = Probability of quality notification PCV = Probability of constraint violation t = Thickness T = Tolerance w = Width w 0 = Zero tolerance width W = Weight Iini = Initial inspection interval I*ini = Initial inspection constraint C = Cost ET = Engineering time LT = Labor time EC = Engineering cost (hourly) LC = Labor time cost (hourly) λ = Tradeoff ratio

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Section: Fig 2 Cross-sectional View Of a Plate With Fastener Hole Atmentioning

confidence: 99%

Aircraft Tolerance Optimization Considering Quality, Manufacturing & Performance

Bhachu

Waycaster

Haftka

et al. 2013

54th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference

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“…In literature, research on cost modelling is rich and varied, both from a general perspective (as discussed in Section 2.1) and from more applied perspectives, for instance through-life costing (Curran et al 2003(Curran et al , 2007b(Curran et al , 2008a, manufacturing cost estimation (Curran et al 2006a(Curran et al , 2006b(Curran et al , 2008c and composite material costing (Curran et al 2008b In fact, the cost model addresses the medium level of fidelity gap that has been identified in Section 2.1. Furthermore, its results enable the parameterisation of the costs and times associated with the discrete manufacturing processes for composite parts.…”

Section: Cost Model Evolutionmentioning

confidence: 99%

Knowledge-based cost modelling of composite wing structures

Verhagen

García²,

Mariot³

et al. 2012

International Journal of Computer Integrated Manufacturing

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The progressive industrialisation of composite-built aircraft is putting manufacturing engineers on a steep learning curve. An opportunity exists to use knowledge management tools to capture, share and reuse knowledge over multiple aircraft programs and maintain the constant flow of learning gained during aircraft program delivery. This article reports on research to develop a knowledge-based cost modelling capability for composite part concept evaluation. The approach integrates a knowledge management environment with a process-based cost estimation tool encoded in very large spreadsheets. To achieve this, the complexity of the cost model is managed by modularising it into simple, re-useable components. The knowledge management environment is then used to manage the knowledge life cycle, knowledge exploitation and knowledge visibility of those components. The result is a flexible cost modelling tool composed of traceable, verifiable and reliable knowledge elements that provides through-life knowledge support for cost engineering. Validation is achieved through functional application of the solution for composite wing top cover cost modelling.

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“…Actually there are many merits for mounting lenses in these kinds of compliant means, but the mounting stiffness needs to be carefully designed in application. This is because if the stiffness is high, tolerances of the mechanical references need to be stringent, which will be costly in manufacturing [13][14][15][16]. Low mounting stiffness will relax mechanical tolerances, but every lens in a lithographic objective vibrates relatively easily due to the dynamic environment, and the focal plane of the optical system vibrates too.…”

Section: Introductionmentioning

confidence: 99%

Inverse axial mounting stiffness design for lithographic projection lenses

2014

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In order to balance axial mounting stiffness of lithographic projection lenses and the image quality under dynamic working conditions, an easy inverse axial mounting stiffness design method is developed in this article. Imaging quality deterioration at the wafer under different axial vibration levels is analyzed. The desired image quality can be determined according to practical requirements, and axial vibrational tolerance of each lens is solved with the damped least-squares method. Based on adaptive interval adjustment, a binary search algorithm, and the finite element method, the axial mounting stiffness of each lens can be traveled in a large interval, and converges to a moderate numerical solution which makes the axial vibrational amplitude of the lens converge to its axial vibrational tolerance. Model simulation is carried out to validate the effectiveness of the method.

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Influence of manufacturing tolerance on aircraft direct operating cost (DOC)

Cited by 20 publications

References 19 publications

Aircraft Tolerance Optimization Considering Quality, Manufacturing & Performance

Aircraft Tolerance Optimization Considering Quality, Manufacturing & Performance

Knowledge-based cost modelling of composite wing structures

Inverse axial mounting stiffness design for lithographic projection lenses

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