Multiaxial Testing of Materials Using a Stewart Platform: Case Study of the Nooru-Mohamed Test

Nierenberger, Mathieu; Poncelet, Martin; Pattofatto, Stéphane; Hamouche, A.; Raka, Bumedijen; Virely, Jean-Marie

doi:10.1111/j.1747-1567.2012.00807.x

Cited by 15 publications

(13 citation statements)

References 21 publications

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“…q = q 1 q 2 q 3 q 4 q 5 q 6 T represents the length of each actuated joint. Further details can be found in [11]. This machine is then used for the NM test, i.e.…”

Section: Loading Machinementioning

confidence: 99%

“…A first experimentation has been performed in [11] using the hexapod presented below in the case study of the NooruMohamed test. It revealed that an advanced control law is needed to use extra DOF to control boundary conditions.…”

Section: Experimental Setup and Modelmentioning

confidence: 99%

“…First experimentation of using a parallel structure for NM test has proven that the instrumentation set up allows a relevant measurement of the displacement field, even for complex load trajectory and very stiff and quasi-brittle specimen [11]. But this experiment also revealed the influence of the compliance of the machine.…”

Section: Introductionmentioning

confidence: 97%

“…Nevertheless, it has been demonstrated that hexapod architectures are suitable for multiaxial testing of materials through a specific case study, the Nooru-Mohamed (NM) test [11] (see fig. 1).…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Enhancing control robustness of a 6 DOF parallel testing machine

Flohic

Paccot

Chanal

2014

2014 European Control Conference (ECC)

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For the first time, a Nooru-Mohammed test was realized using a new kind of loading machine based on gough platform. However, it has been shown that boundary conditions on the concrete specimen are not respected. As a consequence, a new control strategy needs to be developed. This paper aims at applying a well-known control loop based on hybrid force/position law to a loading application. This new control algorithm has been developed according to the task and the structure specificities. Indeed, it permits to realize multi-axial test where the boundary conditions are controlled and respected by using the extra degrees of freedom.

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“…q = q 1 q 2 q 3 q 4 q 5 q 6 T represents the length of each actuated joint. Further details can be found in [11]. This machine is then used for the NM test, i.e.…”

Section: Loading Machinementioning

confidence: 99%

Section: Experimental Setup and Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Enhancing control robustness of a 6 DOF parallel testing machine

Flohic

Paccot

Chanal

2014

2014 European Control Conference (ECC)

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“…These advantages indicate that 6-DOF parallel mechanisms are feasible to the applications of multi-dimensional material testing machines, and some related papers have been published. Nierenberger et al (2014) established a multi-axial testing machine and reproduced the Nooru-Mohamed test. Le Flohic et al (2014) studied the 3D control method to that test machine.…”

Section: Introductionmentioning

confidence: 99%

Development of a material testing machine with multi-dimensional loading capability

Guo

Wang

Chen

et al. 2016

JAMDSM

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This paper presents a multi-dimensional loading material testing machine based on a hexapod parallel mechanism. We designed a model-based PID closed-loop control method using feedbacks from six uniaxial force sensors installed on limbs. Three simulations were proceeded to estimate the feasibility of this control method. Furthermore, we established two series of experiments, including multi-dimensional loading experiments and standard tension tests. The former experiment results demonstrate the multi-axial loading capacity since the actual multi-axial output wrench has the deviation less than 5% of the desired ones. The latter experiments reveal that the uniaxial tension test is not considerably influenced by the redundant degree of freedoms, because the tensile-test results are relatively identical to those results achieved by universal material testing machine. Both experimental results suggest that this proposed material testing machine are feasible to perform multi-dimensional material tests, as well as standard uniaxial tests.

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Novel hexapod-based unidirectional testing and FEM analysis of the RNC isolator

Ismail

2015

Struct. Control Health Monit.

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An innovative Stewart platform (hexapod)-based testing rig is designed, constructed, and used herein to experimentally characterize a seismic isolation device named roll-in-cage (RNC) isolator. The testing rig is a result of integrating a mechanical extension, or upgrade, to the hexapod. This allows for performing up to 15 standard mechanical tests using cylinder, block, prism, beam, plate, or bar specimens, besides reduced-scale prototypes of seismic isolation bearings. Several one-tenth reduced-scale prototypes of the RNC isolator are experimentally examined in this paper using this testing rig. Cyclic horizontal displacement tests are performed considering different test parameters including shear displacement amplitude, axial load, and loading frequency. The RNC isolator's force-displacement relationships, shear stiffness, and damping properties are investigated. Vertical cyclic displacements are also applied to examine the RNC isolator's capability to withstand vertical axial tension. Furthermore, tests at the ultimate level consisting of an increasing-amplitude shear loading, beyond the bearing's design displacement limit, are also carried out to investigate the bearing's behavior after activating its inherent self-stopping, or buffer, mechanism. The obtained experimental outputs are then related to analytical and thorough FEM simulation outputs. This relation is intended to validate those previously developed mathematical and numerical models of the RNC isolator based on the real experimental measurements in this paper. A comparative study of the results is then performed, and the main observations are highlighted.the device are to be carried out in the near future. The experimental characterization tool in this paper is a novel Stewart platform-based testing rig designed by the author and patented [50]. Such characterization tool is basically a mechanical upgrade for the Stewart platform to execute additionally up to 15 standard mechanical tests, besides maintaining its main function as a 3D motion simulator. This transforms the Stewart platform into a 16-in-1 general testing machine and motion simulator (for academic, teaching, and professional purposes) with nearly an additional 5% of the Stewart platform's overall cost. Therefore, this paper attempts first to make a balance between multi-purpose experimental testing's costs, accuracy, and robustness by means of providing a handy, multifunction, and inexpensive experimental testing platform for multidisciplinary implementations. Then, an example of that novel testing platform is constructed to experimentally characterize the RNC isolator. The developed testing platform is capable of testing several types of experimental specimens having block, cylinder, prism, beam, plate, and bar configurations, besides reduced-scale prototypes of seismic isolation bearings. However, only an example for testing seismic isolation bearings' prototypes is constructed for the present study, while more information about the other available designs of that novel testing plat...

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Multiaxial Testing of Materials Using a Stewart Platform: Case Study of the Nooru-Mohamed Test

Cited by 15 publications

References 21 publications

Enhancing control robustness of a 6 DOF parallel testing machine

Enhancing control robustness of a 6 DOF parallel testing machine

Development of a material testing machine with multi-dimensional loading capability

Novel hexapod-based unidirectional testing and FEM analysis of the RNC isolator

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