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2 Journal of Achievements in Materials and Manufacturing Engineering

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Material characterization for laminated glass composite panel

Väer K., Anton J., Klauson A., Eerme M., Õunapuu E., Tšukrejev P.

Journal of Achievements in Materials and Manufacturing Engineering

2017

Vol. 81, nr 1

11--17

Purpose: Laminated glass composite panel (LGCP) with at least one flexible plastic/ viscoelastic interlayer is considered. The purpose of this paper is to determine the material properties of the constituents of LGCP required for accurate modelling of the laminated glass structures. Design/methodology/approach: The proposed approach includes the following three type of tests: non-destructive tests for determining mechanical properties of the glass layers (based on wave propagation), mechanical tests and finite element simulations for determining properties of the interlayers, measuring residual stresses in glass layers using novel methods and equipment (non-destructive, wave propagation based). Findings: Methodology and procedures for determining material properties of the LGCP. Research limitations/implications: Due to fact that the shear moduli of the viscoelastic interlayers and glass skin layers differs up to thousands times, the direct application of the classical sandwich theory may lead to inaccurate results. The layer wise plate theory with viscoelastic interlayer should be applied. In the case of layer wise theory, the material properties should be determined for each layer (not averaged properties for laminate only). Practical implications: The proposed approach allows to determine the properties of the LGCP components with high accuracy and form base for development of accurate plate model for modelling vibration, buckling and bending of the LGCP. The effect of the residual stresses is most commonly omitted in engineering applications. However, in the case of tempered glass the residual stresses are significant and have obviously impact on stressstrain behaviour of the laminated glass panel. Originality/value: Study consists of valuable parts, i.e. determining residual stresses in glass performed in cooperation with private company GlasStress Ltd. Special software and measuring equipment are developed. Further LGCP interlayer mechanical properties are tested experimentally and using simulation tools for design optimization purposes.

Artificial neural networks and evolutionary algorithms in engineering design

Velsker T, Eerme M, Majak J., Pohlak M., Karjust K.

Journal of Achievements in Materials and Manufacturing Engineering

2011

Vol. 44, nr 1

88--95

Purpose: Purpose of this paper is investigation of optimization strategies eligible for solving complex engineering design problems. An aim is to develop numerical algorithms for solving optimal design problems which may contain real and integer variables, a number of local extremes, linear- and non-linear constraints and multiple optimality criteria. Design/methodology/approach: The methodology proposed for solving optimal design problems is based on integrated use of meta-modeling techniques and global optimization algorithms. Design of the complex and safety critical products is validated experimentally. Findings: Hierarchically decomposed multistage optimization strategy for solving complex engineering design problems is developed. A number of different non-gradient methods and meta-modeling techniques has been evaluated and compared for certain class of engineering design problems. The developed optimization algorithms allows to predict the performance of the product (structure) for different design and configurations parameters as well as loading conditions. Research limitations/implications: The results obtained can be applied for solving certain class of engineering design problems. The nano- and microstructure design of materials is not considered in current approach. Practical implications: The methodology proposed is employed successfully for solving a number of practical problems arising from Estonian industry: design of car frontal protection system, double-curved surface forming process modeling, fixings for frameless glazed structures, optimal design of composite bathtub (large composite plastics), etc. Originality/value: Developed numerical algorithms can be utilised for solving a wide class of complex optimization problems.