References of "Staudt, Yves 50003138"
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See detailFailure behaviour of silicone adhesive in bonded connections with simple geometry
Staudt, Yves UL; Odenbreit, Christoph UL; Schneider, Jens

in International Journal of Adhesion & Adhesives (2018), 82

In façade structures, adhesively bonded connections between glass panels and metallic substructures represent an attractive alternative to mechanical fixation devices. Apart from positive aspects ... [more ▼]

In façade structures, adhesively bonded connections between glass panels and metallic substructures represent an attractive alternative to mechanical fixation devices. Apart from positive aspects regarding the construction's energy efficiency and aesthetics, the uniform load transfer reduces stress concentrations in the adherends, which is beneficial especially regarding brittle materials like glass. Structural silicone sealants are generally used for these kind of applications due to their excellent adhesion on glass and their exceptional resistance against environmental influences and ageing. For the verification of the bonded connection, non-linear numerical simulations, such as the Finite Element Method, are increasingly used. The resulting three-dimensional stress states need to be assessed with the help of an appropriate failure criterion. In this paper, an overview is given on available failure criteria for rubber-like materials. The applicability of these criteria on the silicone sealant is verified regarding three characteristic stress states: uniaxial tension, shear and compression. The proposed engineering failure criterion is the true strain magnitude, which is valid for bonded connections in form of linear beads for cohesive failure of the adhesive. For Dow Corning® 993 structural silicone sealant, the strain magnitude, evaluated using true strains, at failure could be determined as 1.6. [less ▲]

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See detailProposal of a Failure Criterion of Adhesively Bonded Connections with Silicone
Staudt, Yves UL

Doctoral thesis (2017)

In the field of façade engineering, structural silicone sealants have been used in adhesively bonded connections since the 1960s. The low strength and stiffness of silicone rubber compared to other types ... [more ▼]

In the field of façade engineering, structural silicone sealants have been used in adhesively bonded connections since the 1960s. The low strength and stiffness of silicone rubber compared to other types of adhesives are compensated by the excellent adhesion properties and the good resistance against ageing and environmental influences, like UV radiation. Silicone sealants show a pronounced nonlinear material behaviour. The applicable design concepts in civil engineering propose simplified design equations, which are based on the assumption of a linear material law. Due to the current state of knowledge and to compensate the simplified model assumptions in the design concept, high reduction factors on the material strength and many restrictions on applications are defined. In order to overcome these drawbacks, the stress state within the sealant is increasingly described using the Finite Element Method. Considering the results of these analysis, the assessment of both the complex stress states with a suitable failure criterion and the influence of stress singularities on the failure behaviour constitute inevitable questions. The present work addresses these two questions. In the first step, the strain magnitude has been determined as a suitable failure criterion for the defect-free bulk material of the considered Dow Corning® 993 structural silicone sealant, subjected to a quasi-static loading. The failure criterion has been calibrated using the results of uniaxial tension as well as circular shear tests and validated with the results of compression tests. The strain magnitude is a strain-based failure criterion, which can be seen as a measure for the distortion of the molecular chains. In a second step, the stress distribution of the single-lap shear joint has been investigated in detail. For the assessment of the singular stresses and strains at the edge area of the interface between the adhesive and the substrate, referred to as two-material wedge, the so-called coupled stress and energy criterion, a concept of Finite Fracture Mechanics, was extended to nonlinear elastic material behaviour. Based on results of conduced simple shear tests on small bonded connections with varying adhesive thicknesses and overlap lengths, the coupled criterion was used to predict the crack initiation loads and a good agreement with the experimentally recorded values was obtained. Knowing the strength and the critical energy release rate of the material, the crack initiation load and the corresponding crack length are determined in the coupled criterion by solving an optimisation problem based on a Finite Element Analysis. The stress partial criterion has been modified to consider the strain magnitude as a failure criterion. In order to analyse the energy partial criterion, the critical energy release rate of Dow Corning® 993 structural silicone sealant has been determined in Double Cantilever Beam tests using the evaluation method based on the J-integral approach. Furthermore, concepts of the Theory of Critical Distances were used to determine the failure loads of the small scale tests. Unlike as for the notched circular shear tests and the tension tests on small scale bonded connections, good predictions were found in the Finite Element Analysis for the simple shear specimens, when a constant element size and formulation at the vicinity of the two-material wedge were used. Similar results were obtained with the point method and the control volume approach. These findings indicate that the characteristic material length for silicone rubber is not constant. [less ▲]

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See detailSilicone sealants: A Finite Fracture Mechanics failure model for non-linear materials
Rosendahl, Philipp L.; Staudt, Yves UL; Odenbreit, Christoph UL et al

in 14th International Conference on Fracture (ICF 14) (2017, June)

A finite fracture mechanics failure model for hyperelastic silicone sealants is presented. The model is in very good agreement with simple shear tests of different adhesive joint geometries.

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See detailNumerical simulation and Identification of the Failure Criterion for Structural Silicone
Staudt, Yves UL; Odenbreit, Christoph UL; Schneider, Jens

Speeches/Talks (2016)

In civil engineering, silicone sealants are widely used in structural sealant glazing applications as an adhesively bonded connection between the glass panels and the building substructure. The current ... [more ▼]

In civil engineering, silicone sealants are widely used in structural sealant glazing applications as an adhesively bonded connection between the glass panels and the building substructure. The current design concept does not take into account the actual stress state and the actual failure mechanism. Therefore, no information about the exact failure probability can be given. Alternative approaches, such as the Finite Element Analysis, also have major disadvantages due to the presence of singularities. Therefore, a method from Finite Fracture Mechanics, calibrated with experimental investigations on bulk material, is applied on silicone sealants, focusing on the shear failure mechanism. The procedure is validated using small scale tests such as simple shear and torsion tests. [less ▲]

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See detailInvestigation of Bonded Connections with Silicone under Shear Loading
Staudt, Yves UL; Odenbreit, Christoph UL; Schneider, Jens

in Bos, Freek; Louter, Christian; Belis, Jan (Eds.) Challenging Glass 5 - Conference on Architectural and Structural Applications of Glass, Ghent, 16 & 17 June 2016 (2016, June 16)

In façade applications, structural sealant glazing systems with a soft adhesive like silicones show a number of advantages especially regarding brittle adherends like glass sheets, as stress ... [more ▼]

In façade applications, structural sealant glazing systems with a soft adhesive like silicones show a number of advantages especially regarding brittle adherends like glass sheets, as stress concentrations in the adherends are avoided due to the large bonding area and the uniform load transfer. The application guideline for structural sealant glazing systems (European Technical Application Guideline ETAG 002) defines a simplified design concept for the silicone sealant, leading to high safety factors and restrictions in use. The material behaviour of the silicone sealant can be more accurately described using the Finite Element Method and hyperelastic material laws, but the results for the stresses at the edge area for a shear dominated loading are highly mesh dependent, due to the presence of a singularity and thus hampering the assessment of the realistic stress distribution. In this paper, shear tests on bonded connections with silicone, referring to the ETAG 002, are presented. Beside the overlap length and adhesive thickness of the specimen prescribed by the standard, two more overlap lengths and thicknesses are tested. For the experimental investigations, the force-deformation behaviour and the failure initiation, observed at the edge area, are recorded. Unlike for the adhesive length, an influence of the specimen thickness on the failure shear strain could be observed and predicted by the numerical simulations. A clear difference between the maximum load and the load at failure initiation was observed. [less ▲]

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See detailInvestigation of the material behaviour of bonded connections with silicone
Staudt, Yves UL; Schneider, Jens; Odenbreit, Christoph UL

in Schneider, Jens; Weller, Bernhard (Eds.) engineered transparency. International Conference at glasstec - Glass | Facade | Energy (2014)

Detailed reference viewed: 170 (12 UL)