Fatigue strength and weight optimization of threaded connections in tie-rods for aircraft structures

Winklberger, Markus; Heftberger, Peter; Sattlecker, Mario; Schagerl, Martin

doi:10.1016/j.proeng.2018.02.037

Cited by 12 publications

(6 citation statements)

References 4 publications

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“…These fatigue tests include necked lug specimens with three different geometries, labeled D27, D29 and D31 according to the outer lug diameter D, Table 1. Features without dimensions are a standard groove for a sealing ring and a M10-thread for mounting the necked lug to the tie-rod tube [15]. These features are assumed to have no influence on the fatigue and fracture behavior of the investigated necked lugs.…”

Section: Fatigue Tests 21 Specimen Detailsmentioning

confidence: 99%

“…The fatigue tests are conducted using a hydraulic multipurpose test rig accommodating a servo hydraulic cylinder from manufacturer Zwick Roell with a maximum load capability of 100 kN. Special clamping devices are used along with an alignment device to assure axial loading of specimens [15], Figure 2. In constant amplitude fatigue tests a frequency of 10 Hz for load amplitudes of 5.78 kN-22.5 kN is used.…”

Section: Test Setup and Proceduresmentioning

confidence: 99%

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On the fatigue and fracture behavior of necked double shear lugs for aircraft applications

Winklberger

Schagerl

2020

Materialwissenschaft Werkst

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The fatigue and fracture behavior of double shear lugs subjected to axial loading is investigated. The focus is on specific shapes, so‐called waisted or necked lugs. These structural components used in aircraft interior are prone to fatigue loads. Three different sizes of necked double shear lugs made of high strength aluminum 2024‐T351 and steel 17–4 PH are tested using constant amplitude cyclic loadings with a load ratio R = 0.01. Measurement data is used to identify the number of cycles to crack initiation and final fracture. Fatigue tests show that cracks initiate either at the inside or outside surface of necked lugs. However, no clear dependency on the load amplitude, lug size and material could be found. Numerical simulations using both conventional finite element method (FEM) and extended finite element method (XFEM) are performed to calculate the stress intensity factors (SIFs) for multiple crack lengths of straight and necked double shear lugs. Calculated stress intensity factors for straight lugs fit well to stress intensity factors reported in literature. Stress intensity factor curves of inside and outside cracks of necked lugs plotted with respect to crack length, cross each other, which could have an influence on the fracture behavior observed in fatigue tests.

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Section: Fatigue Tests 21 Specimen Detailsmentioning

confidence: 99%

Section: Test Setup and Proceduresmentioning

confidence: 99%

On the fatigue and fracture behavior of necked double shear lugs for aircraft applications

Winklberger

Schagerl

2020

Materialwissenschaft Werkst

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“…In contrast to the flat lug considered in this contribution lugs in real applications are commonly made by turning with a following milling process. Furthermore, necked double shear lugs in real applications usually have a threaded shaft and are equipped with spherical bearings [ 31 ]. However, the simplified shape of the chosen lug has multiple advantages for presented investigations: (i) the production effort is minimized, (ii) the simple shape can be easily meshed for FE simulations, (iii) the application of PWAS is eased due to flat surfaces and (iv) the possibility to use simple analytical approaches for investigation.…”

Section: Lug Geometry and Materialsmentioning

confidence: 99%

Crack Identification in Necked Double Shear Lugs by Means of the Electro-Mechanical Impedance Method

Winklberger

Kralovec

Humer

et al. 2020

Sensors

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This contribution investigates fatigue crack detection, localization and quantification in idealized necked double shear lugs using piezoelectric transducers attached to the lug shaft and analyzed by the electro-mechanical impedance (EMI) method. The considered idealized necked lug sample has a simplified geometry and does not includes the typical bearing. Numerical simulations with coupled-field finite element (FE) models are used to study the frequency response behavior of necked lugs. These numerical analyses include both pristine and cracked lug models. Through-cracks are located at 90∘ and 145∘ to the lug axis, which are critical spots for damage initiation. The results of FE simulations with a crack location at 90∘ are validated with experiments using an impedance analyzer and a scanning laser Doppler vibrometer. For both experiments, the lug specimen is excited and measured using a piezoelectric active wafer sensor in a frequency range of 1 kHz to 100 kHz. The dynamic response of both numerical calculations and experimental measurements show good agreement. To identify (i.e., detect, locate, and quantify) cracks in necked lugs a two-step analysis is performed. In the first step, a crack is detected data-based by calculating damage metrics between pristine and damaged state frequency spectra and comparing the resulting values to a pre-defined threshold. In the second step the location and size of the detected crack is identified by evaluation of specific resonance frequency shifts of the necked lug. Both the search for frequencies sensitive to through-cracks that allow a distinction between the two critical locations and the evaluation of the crack size are model-based. This two-step analysis based on the EMI method is demonstrated experimentally at the considered idealized necked lug, and thus, represents a promising way to reliably detect, locate and quantify fatigue cracks at critical locations of real necked double shear lugs.

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“…When the mechanical equipment is in operation, the part of the thread connection will bear larger radial, axial and shear loads. Therefore, the influence of thread forming quality on the service performance of mechanical equipment is crucial [2][3][4].…”

Section: Introductionmentioning

confidence: 99%

Research and Optimization of Extrusion Tap Structure Based on Numerical Simulation and Experimental Analysis

Tao,

Wan,

et al. 2024

Materials

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In order to enhance the quality of thread processing by tap, a systematic analysis of its forming mechanism and factors affecting forming quality is conducted. Effects of the number of edges, the amount of shovel back, the extrusion cone, the calibration part and the extrusion cone angle on the torque and temperature are achieved by finite element analysis and experiments. From the perspective of reducing torque and temperature during the forming process, the optimal combination of tap structural parameters for machining M22×2 internal threads on 42CrMo4 high-strength steel are further obtained through orthogonal optimization. The results show that, unlike the cutting process of threads, the extrusion forming process of threads is a net forming process in which metal undergoes plastic deformation in a limited space, and the metal material continuously flows along the edge of the V-shaped groove of the tap, gradually piling up to form the thread tooth shape. This also caused a noticeable lack of flesh at the top of the extruded thread teeth. Better quality threads can be obtained by machining with optimized structural parameters. The maximum torque and temperature during the machining process are reduced by 22.86% and 20.31%, respectively. The depth of the hardened layer increased by 0.05 mm, and the root and top hardness of the teeth increased by 10 HV0.2 and 5 HV0.2, respectively.

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Fatigue strength and weight optimization of threaded connections in tie-rods for aircraft structures

Cited by 12 publications

References 4 publications

On the fatigue and fracture behavior of necked double shear lugs for aircraft applications

On the fatigue and fracture behavior of necked double shear lugs for aircraft applications

Crack Identification in Necked Double Shear Lugs by Means of the Electro-Mechanical Impedance Method

Research and Optimization of Extrusion Tap Structure Based on Numerical Simulation and Experimental Analysis

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