Tag Archives: elongation

1062–1070 V. Kolář, M. Tichý, M. Müller, P. Valášek and A. Rudawska
Research on influence of cyclic degradation process on changes of structural adhesive bonds mechanical properties
Abstract |

Research on influence of cyclic degradation process on changes of structural adhesive bonds mechanical properties

V. Kolář¹*, M. Tichý¹, M. Müller¹, P. Valášek¹ and A. Rudawska²

¹Czech University of Life Sciences, Faculty of Engineering, Department of Material Science and Manufacturing Technology, Faculty of Engineering, Kamýcká 129, CZ165 21 Prague, Czech Republic
²Lublin University of Technology, Department of Production Engineering, Mechanical Engineering Faculty, Nadbystrzycka 36, PL20 618 Lublin, Poland
*Correspondence: vkolar@tf.czu.cz

Abstract:

The paper deals with an influence of a cyclic degradation process on changes of a shear tensile strength of single lap-shear adhesive bonds and their elongation according to ČSN EN ISO 9142. Five one-component structural adhesives used in a construction of car body works were used within the research. The degradation of adhesive bonds is a significant factor which influences a quality and a service life of adhesive bonds exposed to environment. A main requirement in production companies is not only reaching satisfactory initial mechanical properties but namely ensuring a reliability and a safety of adhesive bonds during their usage.
These reasons show a great importance of adhesive bonds tests either directly in the operating environment or by a simulation of operating conditions in laboratories. The degradation process of adhesive bonds worsens mechanical properties of not only the bond itself but also of the bonded material. This process is progressing and it is usually permanent and irreversible. It is a change of mechanical and physical properties which can endanger a safety and a reliability of parts, prospectively of the whole equipment. It can leads up to a complete failure of its function in the extreme case. A temperature, a moisture, a direct contact with water and chemicals or an atmospheric corrosion belong among the most serious degradation agents. It is important to take into regard time of the processes influence at the same time which can act either independently or concurrently when their effects grow stronger.
From that reason the adhesive bonds were exposed to the cyclic degradation process according to the standard ČSN EN ISO 9142. Subsequently, the adhesive bonds mechanical properties were tested on universal testing machine and by means of SEM analysis (TESCAN MIRA 3).
Results of mechanical tests proved a fall of the shear tensile strength of single lap-shear adhesive bonds after 42 cycles of the degradation process of 12.8 to 21.7%. The bond strength fall was gradual and it showed a linear trend at some adhesives. Other adhesives showed a significant fall after the exposition to the degradation process after which the strength fall stabilized.

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1257-1265 M. Tichý, M. Müller, P. Valášek and I. Miturska
Effect of rubber powder from waste tyre rubbers on mechanical properties of one-component polyurethane putty
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Effect of rubber powder from waste tyre rubbers on mechanical properties of one-component polyurethane putty

M. Tichý¹*, M. Müller¹, P. Valášek¹ and I. Miturska²

¹Czech University of Life Sciences, Faculty of Engineering, Department of Material Science and Manufacturing Technology, Faculty of Engineering, Kamýcká 129, CZ165 21 Prague, Czech Republic
²Lublin University of Technology, Department of Production Engineering, Mechanical Engineering Faculty, Nadbystrzycka 36, PL20 618 Lublin, Poland
*Correspondence: xticm001@studenti.czu.cz

Abstract:

The utilization of adhesives in technical practice is varied. Adhesives serve for a creation of strength bonds on the one hand, and on the other hand e.g. for cementing. The aim of the research is a modification of one-component polyurethane putty RPS 45 used in automotive industry to increase strength properties in an adhesive bond. An interaction between a filler in the form of rubber powder micro-particles and one-component polyurethane adhesive was investigated by means of SEM analysis. Sealing is a primary property of this putty. Sealing putties usually reach very small strength which can be increased by an admixture of the filler. In order to keep elastic properties, micro-particles of the rubber powder gained from tyre recycling process were used as the filler. An aspect of a loading speed of the adhesive bond is essential at the practical application at which the adhesive bond can be failed in adhesive or cohesive layers. The adhesive bond can be perceived in terms of its function as a complex of three layers, i.e. an adhesive bonded material, the interaction between the adhesive and the adhesive bonded material and the adhesive layer itself. There are often states in the practices when the adhesive bonds are exposed to the loading which can be either a static or a dynamic one. That is why the research is focused not only on the evaluation of the influence of the modification of the one-component polyurethane adhesive, but also on the influence of the loading speed of the adhesive bond. Tested speeds set on a universal testing machine Zwick/Roell Z150 were 2, 50 and 100 mm min-1. The results of mechanical tests proved a positive influence of the filler on the strength σm higher by 42.68 ± 6.96% and the elongation at break εb higher by 12.2 ± 20.95%. On the contrary, the stress at yield σy was decreased.

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654-661 A. Krofová and M. Müller
Influence of dusty micro-particles contamination on adhesive bond strength
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Influence of dusty micro-particles contamination on adhesive bond strength

A. Krofová* and M. Müller

Department of Material Science and Manufacturing Technology, Faculty of Engineering, Czech University of Life Science, Kamýcká 129, CZ-16521 Prague, Czech Republic; *Correspondence: krofovaa@tf.czu.cz

Abstract:

A necessity for a bond creation is one of common attributes of production companies. An adhesive bonding technology is a method of a connecting. This method is suitable for workings with a single and serial production. Many research projects dealt with a preparation of adhesive bonds, degradation aspects etc. An area, which has not been properly investigated at present, is an influence of a contamination of the adhesive bonds by dusty micro-particles, e. g. from a ventilation of assembly shops, production hall etc. The research was focused on the evaluation of the influence of dusty micro-particles contamination of the two-component epoxy adhesive at the hardening process. The dusty micro-particles were gained from the filtering equipment used in a production hall. Sizes of gained dusty particles were analysed on sieves of dimensions 315 μm, 250 μm, 160 μm, 90 μm. Subsequently, these particles were added in various ratios into the mixture of the adhesive during its preparation. The adhesive bonds containing the dusty particles of the sizes 250 µm, 160 µm and 90 µm showed the fall of the adhesive bond strength. The adhesive bonds containing the dusty particles of the size 315 µm showed the mild increase of the adhesive bond strength. The failure area did not change owing to the contamination of the adhesive bond with the dusty particles.

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