Triaxial fatigue testing machine for polymeric materials

Part 1 of this paper is concerned with the design and development of a multiaxial fatigue testing machine. The machine structure is considered in some detail to emphasize the dynamic as well as the static stability essential in machines applying fatigue loading. The machine is capable of testing specimens of the same geometry in torsion, push-pull, and internal pressure (if hollow), either statically or dynamically. These test modes can be operated independently or in combination, both in phase and out of phase. Each mode can be stress or strain dependent. Part 2 deals with the associated extensometry, test procedures, and preliminary tests on polymethylmethacrylate. These preliminary tests, originally undertaken to test the capability of the machine, whilst not extensive enough to be considered rigorous, are included to illustrate some of the interesting potentialities of multiaxial testing.

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Crack mode and life of Ti-6Al-4V under multiaxial low cycle fatigue

Frattura ed Integrità Strutturale ◽

10.3221/igf-esis.34.54 ◽

2015 ◽

Author(s):

Takamoto Itoh ◽

Masao Sakane ◽

Takahiro Morishita ◽

Hiroshi Nakamura ◽

Masahiro Takanashi

Keyword(s):

Hollow Cylinder ◽

Stress Ratio ◽

Biaxial Loading ◽

Fatigue Testing ◽

Low Cycle Fatigue ◽

Testing Machine ◽

Multiaxial Fatigue ◽

Cycle Fatigue ◽

Loading Test ◽

Failure Life

This paper studies multiaxial low cycle fatigue crack mode and failure life of Ti-6Al-4V. Stress controlled fatigue tests were carried out using a hollow cylinder specimen under multiaxial loadings of ?=0, 0.4, 0.5 and 1 of which stress ratio R=0 at room temperature. ? is a principal stress ratio and is defined as ?=sigmaII/sigmaI, where sigmaI and sigmaII are principal stresses of which absolute values take the largest and middle ones, respectively. Here, the test at ?=0 is a uniaxial loading test and that at ?=1 an equi-biaxial loading test. A testing machine employed is a newly developed multiaxial fatigue testing machine which can apply push-pull and reversed torsion loadings with inner pressure onto the hollow cylinder specimen. Based on the obtained results, this study discusses evaluation of the biaxial low cycle fatigue life and crack mode. Failure life is reduced with increasing ? induced by cyclic ratcheting. The crack mode is affected by the surface condition of cut-machining and the failure life depends on the crack mode in the multiaxial loading largely.

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Development of a deflection controlled multiaxial fatigue testing machine

KSME Journal ◽

10.1007/bf02954030 ◽

1990 ◽

Vol 4 (2) ◽

pp. 103-108 ◽

Cited By ~ 2

Author(s):

Soon -Bok Lee

Keyword(s):

Fatigue Testing ◽

Testing Machine ◽

Multiaxial Fatigue

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A biaxial fatigue testing machine for thin-walled tubes under axial load and internal pressure at elevated temperatures Soret, N., Bernadou, J.-P. and Marsac, S. Proc. 4th Int. Conf. on Biaxial/Multiaxial Fatigue II, St. Germain en Laye, France, 31 May–3 June 1994, pp. 221–232

International Journal of Fatigue ◽

10.1016/s0142-1123(97)87158-7 ◽

1996 ◽

Vol 18 (8) ◽

pp. 609

Keyword(s):

Internal Pressure ◽

Axial Load ◽

Elevated Temperatures ◽

Fatigue Testing ◽

Testing Machine ◽

Multiaxial Fatigue ◽

Biaxial Fatigue ◽

Thin Walled

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Crack Growth Orientation in Two Structural Materials under Multiaxial Fatigue Loading

Materials Science Forum ◽

10.4028/www.scientific.net/msf.587-588.892 ◽

2008 ◽

Vol 587-588 ◽

pp. 892-897

Author(s):

Luís G. Reis ◽

Bin Li ◽

Manuel de Freitas

Keyword(s):

Testing Machine ◽

Experimental Studies ◽

Complex Loading ◽

Fatigue Loading ◽

Structural Materials ◽

Optical Microscope ◽

Fatigue Tests ◽

Multiaxial Fatigue ◽

Loading Path ◽

Biaxial Testing

In real engineering components and structures, many accidental failures are due to unexpected or additional loadings, such as additional bending or torsion, etc. Therefore, it has attracted more research attentions to study the mechanical behavior of materials under complex loading conditions. Two typical structural materials are studied and compared in this paper: AISI 303 stainless steel and 6060-T5 Aluminum alloy. The objective is to study the effects of multiaxial loading paths on the crack initiation and orientation of the two materials studied. Fatigue tests were conducted in a biaxial testing machine. Fractographic analyses of the fracture surface were carried out by optical microscope and SEM approaches. In addition to the experimental studies, theoretical predictions of the damage plane were made using critical plane approaches. Comparisons of the predicted orientation of the damage plane with the experimental observations are shown. The applicability of the multiaxial fatigue criteria for the two materials is discussed. It was shown that the two materials studied have different crack orientations under the same loading path. This observation appears to show that the applicability of the fatigue models is dependent on the material type and multiaxial microstructure characteristics.

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Experimental and Numerical Investigation of Circular Arc Dovetail Attachments under Fatigue Loading

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.541-542.564 ◽

2014 ◽

Vol 541-542 ◽

pp. 564-568

Author(s):

Liang Shi ◽

Da Sheng Wei ◽

Yan Rong Wang

Keyword(s):

Stress Distribution ◽

Fatigue Testing ◽

Testing Machine ◽

Bending Moment ◽

Fatigue Loading ◽

Fretting Fatigue ◽

Circular Arc ◽

Fan Blade ◽

Number Of Cycles ◽

Actual Geometry

Fretting fatigue is an important failure mode of dovetail attachments in gas turbine engines. One of the most difficult challenges in carrying out experiments of components with actual geometry is the design of fixtures for the dovetail attachments since it can change the stress distribution under a given load. A circular arc dovetail attachment specimen with a tenon at each end respectively was designed and machined to simulate the fatigue damage that occurs in wide-chord fan blade attachments, so it can perform two dovetail attachment simulations at each time, and its related fixture was connected with the testing machine by two pins which were orthogonal to each other so as to eliminate additional bending moment. An Instron 8802 servo-hydraulic fatigue testing system was used to provide fatigue loads. Furthermore, Finite Element (FE) analysis based on the experimental configuration was carried out to obtain the stress distribution on the contact surface, crack initiation location and number of cycles to the fretting fatigue failure were predicted based on the FE results. The results show a good agreement with the experimental counterparts.

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Bending and Torsion Fatigue-Testing Machine Developed for Multiaxial Non-Proportional Loading

Metals ◽

10.3390/met9101115 ◽

2019 ◽

Vol 9 (10) ◽

pp. 1115 ◽

Cited By ~ 1

Author(s):

Fumio Ogawa ◽

Yusuke Shimizu ◽

Stefano Bressan ◽

Takahiro Morishita ◽

Takamoto Itoh

Keyword(s):

Fatigue Life ◽

Fatigue Testing ◽

Testing Machine ◽

Fatigue Tests ◽

Multiaxial Fatigue ◽

304 Stainless Steel ◽

Testing Time ◽

Loading Conditions ◽

Proportional Loading ◽

Bending Loading

A new fatigue-testing machine was developed to perform high-cycle multiaxial fatigue tests at 50 Hz, in order to reduce testing time. The developed machine can combine bending and torsion loading and perform fatigue tests at a high frequency, under proportional and non-proportional loading conditions, where the principal stress direction changes during a cycle. The proportional loading is cyclic bending loading, and the non-proportional loading is cyclic, combining bending and reversed torsion loading. In this study, the effectiveness of the testing machine was verified by conducting tests under these loading conditions, using specimens of type 490A hot-rolled steel and type 304 stainless steel. The fatigue life linked to bending loading obtained using the new testing machine was slightly extended compared with that obtained using the conventional fatigue-testing machine. The fatigue life derived as a result of a combination of bending and torsion was comparable to that obtained using the conventional fatigue-testing machine, although a fatigue limit reduction of 100 MPa was observed compared to the former study. The feasibility of tests using the developed multiaxial fatigue-testing machine was confirmed.

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Review of Multiaxial Testing for Very High Cycle Fatigue: From ‘Conventional’ to Ultrasonic Machines

Machines ◽

10.3390/machines8020025 ◽

2020 ◽

Vol 8 (2) ◽

pp. 25

Author(s):

Pedro Costa ◽

Richard Nwawe ◽

Henrique Soares ◽

Luís Reis ◽

Manuel Freitas ◽

...

Keyword(s):

High Cycle Fatigue ◽

Fatigue Testing ◽

Fatigue Tests ◽

Multiaxial Fatigue ◽

Cycle Fatigue ◽

New Materials ◽

Multiaxial Testing ◽

Very High Cycle Fatigue ◽

Ultrasonic Fatigue ◽

Very High

Fatigue is one of the main causes for in service failure of mechanical components and structures. With the development of new materials, such as high strength aluminium or titanium alloys with different microstructures from steels, materials no longer have a fatigue limit in the classical sense, where it was accepted that they would have ‘infinite life’ from 10 million (107) cycles. The emergence of new materials used in critical mechanical parts, including parts obtained from metal additive manufacturing (AM), the need for weight reduction and the ambition to travel greater distances in shorter periods of time, have brought many challenges to design engineers, since they demand predictability of material properties and that they are readily available. Most fatigue testing today still uses uniaxial loads. However, it is generally recognised that multiaxial stresses occur in many full-scale structures, being rare the occurrence of pure uniaxial stress states. By combining both Ultrasonic Fatigue Testing with multiaxial testing through Single-Input-Multiple-Output Modal Analysis, the high costs of both equipment and time to conduct experiments have seen a massive improvement. It is presently possible to test materials under multiaxial loading conditions and for a very high number of cycles in a fraction of the time compared to non-ultrasonic fatigue testing methods (days compared to months or years). This work presents the current status of ultrasonic fatigue testing machines working at a frequency of 20 kHz to date, with emphasis on multiaxial fatigue and very high cycle fatigue. Special attention will be put into the performance of multiaxial fatigue tests of classical cylindrical specimens under tension/torsion and flat cruciform specimens under in-plane bi-axial testing using low cost piezoelectric transducers. Together with the description of the testing machines and associated instrumentation, some experimental results of fatigue tests are presented in order to demonstrate how ultrasonic fatigue testing can be used to determine the behaviour of a steel alloy from a railway wheel at very high cycle fatigue regime when subjected to multiaxial tension/torsion loadings.

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