SHM—Prognostic Analysis of Tapered Attachment Lugs Under Fatigue Loading

Bharath, K.; Kumar, Bhawesh; Chikmath, L.; Dattaguru, B.

doi:10.1007/978-981-10-7197-3_47

Cited by 3 publications

(3 citation statements)

References 13 publications

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“…lug-hole boundary. Convergence study results are chosen from the earlier works depending on suitable number of degrees of freedom (Bharath et al, 2018). The far end of the attachment lugs is supported on rollers; further, the rigid body displacement/motion is suppressed in both the longitudinal and transverse direction (Figure 1).…”

Section: Boundary Conditions and Finite Element Modellingmentioning

confidence: 99%

A study on prognostic analysis of attachment lugs under off-axis loading

Kenchappa

Chikmath

Dattaguru

2019

IJSI

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Purpose Lug joints with fasteners play a crucial role in connecting many major components of the aircraft. Most of the failures in the past were credited to the damages initiating and progressing from these types of joints. Ensuring the structural integrity of these fastener joints is a major issue in many engineering structures, especially in aerospace components, which would otherwise lead to fatal failure. The purpose of this paper is to adopting the prognostic approach for analysing these lug joints with fasteners subjected to off-axis loading by estimating the crack initiation and crack growth life of these joints. This data will be useful to estimate the remaining life of these joints at any given stage of operations, which is mandatory in structural health monitoring (SHM). Design/methodology/approach Straight and tapered lug joints are modelled using the finite element method in MSC PATRAN and analysed in MSC NASTRAN. These lug joints are analysed with a push fit fastener. The contact/separation regions at the pin–lug interface are carefully monitored throughout the analysis for various loading conditions. Critical locations in these lug joints are identified through stress analysis. Fatigue crack initiation and fatigue crack growth analysed is carried out at these locations for different load ratios. A computational method is proposed to estimate the cycles to reach crack initiation and cycles at which the crack in the lug joint become critical by integrating several known techniques. Findings Analysis carried out in this paper describes the importance of tapered lug joints, particularly when subjected to non-conventional way of loading, i.e. off-axis loading. There is a partial loss of contact between pin and lug upon pin loading, and this does not change further with monotonically increasing pin load. But during load reversals, there is a change in contact/separation regions which is effectively handled by inequality constraints in the boundary conditions. Crack growth in these lug joints pertains to mixed-mode cracking and is computed through the MVCCI technique. Originality/value Most of the earlier works were carried out on in-plane pin loading along the axis of symmetry of the lug. The current work considers the off-axis pin loading by loading the lug joints with transverse and oblique pin load. The significance of taper angle under such loading condition is brought in this paper. The results obtained in this paper through prognostic approach are of direct relevance to the SHM and damage tolerance design approach where the safety of the structural components is of foremost priority.

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Section: Boundary Conditions and Finite Element Modellingmentioning

confidence: 99%

A study on prognostic analysis of attachment lugs under off-axis loading

Kenchappa

Chikmath

Dattaguru

2019

IJSI

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“…As a kind of important aircraft structural component, lug joints act as primary load-carrying members and are more susceptible to failure due to fatigue crack. 25 The article is organized as follows: In Section 2, the mathematical background of the heteroscedasticity treatment based on GP quantile regression is described. Section 3, which follows, introduces the fatigue experiment of attachment lugs and the method validation.…”

Section: Introductionmentioning

confidence: 99%

“…As a kind of important aircraft structural component, lug joints act as primary load-carrying members and are more susceptible to failure due to fatigue crack. 25…”

Section: Introductionmentioning

confidence: 99%

A new GW-based heteroscedastic Gaussian process method for online crack evaluation

Wang

Yuan

et al. 2022

Structural Health Monitoring

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Accurate evaluation of fatigue crack by using structural health monitoring (SHM) methods is very important to the life management of aircraft structures. However, fatigue crack propagation is always a complicated process for individual aircraft structures during their long-term service. And the monitoring has to be performed under different environmental and operational conditions. These factors result in the uncertain distribution of the damage index obtained by SHM. The distribution usually changes along with the service time, which can be defined as heteroscedasticity. The heteroscedasticity characteristic of the uncertain distribution of damage index has an important negative impact on the SHM based diagnostics algorithms if not considered during the evaluation. However, till now, few researchers have considered this important aspect. To improve the evaluation accuracy under different environmental and operational conditions for individual aircraft, this paper proposes a new guided wave-based heteroscedastic Gaussian process method. Gaussian process quantile regression is adopted to estimate the conditional quantiles of the damage index distribution during the service to deal with the heteroscedasticity. The method is validated on an attachment lug fatigue test, an important aircraft structural component. The experimental results demonstrate that the proposed method can quantify the heteroscedastic uncertainty associated and obviously improve the quality of crack evaluation. For the serious heteroscedastic specimen, the maximum evaluation is only 0.7 mm reduced from the original 7.4 mm, which is an order of magnitude.

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Prognosis analysis of tapered lugs with interference and clearance fits under fatigue loading

Bharath

Chikmath

2017

ISSS J Micro Smart Syst

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SHM—Prognostic Analysis of Tapered Attachment Lugs Under Fatigue Loading

Cited by 3 publications

References 13 publications

A study on prognostic analysis of attachment lugs under off-axis loading

A study on prognostic analysis of attachment lugs under off-axis loading

A new GW-based heteroscedastic Gaussian process method for online crack evaluation

Prognosis analysis of tapered lugs with interference and clearance fits under fatigue loading

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