Contactless and Frictionless Pure Bending

Boers, Sha Sebastiaan; Geers, Mgd Marc; Kouznetsova, V Varvara

doi:10.1007/s11340-009-9257-2

Cited by 20 publications

(10 citation statements)

References 18 publications

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“…The sample dimensions imply a plain strain condition in the direction parallel to the rotational axis. A reversed loading test can be trivially performed by simply applying an opposite bending moment (Boers et al, 2009).…”

Section: Plain Strain Pure Bendingmentioning

confidence: 99%

Experimental characterization and model identification of directional hardening effects in metals for complex strain path changes

Boers

Schreurs

Geers

et al. 2010

International Journal of Solids and Structures

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a b s t r a c tThe purpose of the current work is the development and application of a new experimental technique and testing device for investigating the complex behavior of sheet metals during non-proportional loading. The method is based on plain strain pure bending, enabling the investigation of large deformation cyclic reversed loading, orthogonal pure bending, as well as springback. The key feature of the pure bending experiment is the absence of contact forces, material slip and friction. Furthermore, during the pure bending test, the strain gradient through the thickness is kinematically prescribed because the specimen is subjected to a plane strain condition in de direction parallel to the rotational axis (Tan et al., 1995), which allows for a straightforward comparison of the pure bending experiments and parallel simulations. The latter is used here via the identification of a recent model for directional hardening effects and arbitrary strain path changes, (Wang et al., 2006(Wang et al., , 2008. The current method facilitates experimental investigation of hardening stagnation after reverse loading and cross hardening going well beyond that which is possible with existing methods based on the cyclic shear or tension-shear of sheet metal strips (Bouvier et al., 2005(Bouvier et al., , 2006aFlores et al., 2007.), or pure and three-point bending (

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Section: Plain Strain Pure Bendingmentioning

confidence: 99%

Experimental characterization and model identification of directional hardening effects in metals for complex strain path changes

Boers

Schreurs

Geers

et al. 2010

International Journal of Solids and Structures

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“…to test samples in combination with microscopy. Boers et al [6] replaced Yoshida's sliders for frictionless air bearings, enabling their setup to perform large amplitude, cyclic, pure bending in a contactless and frictionless fashion. Boers et al also notes that in general, influences of contact and friction are not included in numerical tests.…”

Section: Requirements Of the Bending Testmentioning

confidence: 99%

“…For the here presented bending setup in-situ SEM observation of bending failure during the bending test is also an important requirement, as it will greatly enhance the possibilities to unravel the underlying physical origin of the bending failure. A contactless, frictionless pure bending setup for large amplitude, cyclic loading was developed by Boers et al [6] which can be used to achieve the first two points listed above. However, simply miniaturizing the contactless, frictionless pure bending setup developed by Boers et al such that it fits SEM is not trivial.…”

Section: Requirements Of the Bending Testmentioning

confidence: 99%

A miniaturized contactless pure-bending device for in-situ SEM failure analysis

Hoefnagels

Buizer

Geers

2011

Experimental and Applied Mechanics, Volume 6

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“…More complex systems for biomechanical testing of spine segments have been proposed [19,20]. The testing systems for larger samples of generic shape are even more complex [21]. These few examples have been reviewed to highlight the difficulty of producing pure bending; when mechanisms are designed for testing of materials, high complexity is acceptable.…”

Section: Introductionmentioning

confidence: 99%

Synchronicity and pure bending of bimorphs: a new approach to piezoelectric energy harvesting

Pozzi

2018

Smart Mater. Struct.

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Kinetic energy harvesting with piezoelectric bimorphs has attracted considerable research interest in recent years. Many works have been dedicated to the modelling and optimisation of the cantilevered geometry to increase power density, bandwidth, etc. The increased efficiency coming from the use of trapezoidal beams has been recognised, but little has been done to produce the same uniform strain within the most commonly available rectangular beams. This work proposes a new approach via a smart compliant structure which permits to deform a set of bimorphs in pure bending. Furthermore, since the deflections are synchronous, the power signals produced are in phase and power conditioning is simplified and made more efficient. The kinematic requirements for uniform strain are discussed, the novel structure is proposed and modelled with finite elements, a prototype is presented and characterised to support the modelling. The proposed structure induces almost perfectly uniform strain in the piezoelectric beams for all useful rotation angles, demonstrating that, compared to a traditional cantilever, twice as many charges can be produced when the same maximum strain is applied to the material. Synchronicity is also experimentally verified for the prototype, as power signals resulting from impact excitation are observed to be in phase. The principle of synchronous pure bending via helper structures can be applied in general to increase the performance of piezoelectric energy harvesters.

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Contactless and Frictionless Pure Bending

Cited by 20 publications

References 18 publications

Experimental characterization and model identification of directional hardening effects in metals for complex strain path changes

Experimental characterization and model identification of directional hardening effects in metals for complex strain path changes

A miniaturized contactless pure-bending device for in-situ SEM failure analysis

Synchronicity and pure bending of bimorphs: a new approach to piezoelectric energy harvesting

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