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Abstract

In this paper were conducted virtual tests to assess the impact of geometry changes on the response of metallic hexagonal honeycomb structures to applied loadings. The lateral compressive stress state was taken into consideration. The material properties used to build numerical models were assessed in laboratory tests of aluminium alloy 7075. The modelling at meso-scale level allow to comprehensive study of honeycomb internal structure. The changes of honeycomb geometry elements such as: fillets radius of the cell edges in the vicinity of hexagonal vertexes, wall thickness were considered. The computations were conducted by using finite element method with application of the ABAQUS finite element method environment. Elaborated numerical models allowed to demonstrate sensitivity of honeycomb structures damage process response to geometry element changes. They are a proper tools to perform optimization of the honeycomb structures. They will be also helpful in designing process of modern constructions build up of the considered composite constituents in various branches of industry. Moreover, the obtained results can be used as a guide for engineers. Conducted virtual tests lead to conclusion that simplification of the models of internal honeycomb structure which have become commonplace among both engineers and scientist can lead to inaccurate results.
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Authors and Affiliations

T. Sadowski
D. Pietras
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Abstract

This paper presents a new algorithm that approximates the forces that develop between a human hand and the handles of a climbing wall. A hand-to-handle model was developed using this algorithm for the Open Dynamics Engine physics solver, which can be plugged into a full-body climbing simulation to improve results. The model data are based on biomechanical measurements of the average population presented in previously published research. The main objective of this work was to identify maximum forces given hand orientation and force direction with respect to the climbing wall handles. Stated as a nonlinear programming problem, solution was achieved by applying a stochastic Covariance Matrix Adaptation Evolution Strategy (CMA-ES). The algorithm for force approximation works consistently and provides reasonable results when gravity is neglected. However, including gravity results in a number of issues. Since the weight of the hand is small in relation to the hand-to-handle forces, neglecting gravity does not significantly affect the reliability and quality of the solution.

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Bibliography

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Authors and Affiliations

Grzegorz Orzechowski
1 2
Perttu Hämäläinen
3
Aki Mikkola
1

  1. Department of Mechanical Engineering, LUT University, Lappeenranta, Finland.
  2. Mevea Ltd., Lappeenranta, Finland.
  3. Department of Computer Science, Aalto University, Espoo, Finland.
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Abstract

The presented paper concerns a novel concept of hybrid piezoelectric motor based on electroactive lubrication principle. Its structure is combined of quasi-static and resonance piezoelectric actuators, synchronizing their work to generate the rotary movement. The hybrid motor topology is compared to the existing piezoelectric motors, regarding its field of applications in embedded systems with very high security requirements. The electroactive lubrication principle is briefly presented with regards to optimization of the hybrid motor. The performance principle of the hybrid motor is described in terms of its working cycle. The assembling process of the prototype hybrid motor is briefly explained with emphasis put on the frequency and impedance tuning of the applied quasi-static and resonance piezoelectric actuators. Next, the hybrid motor power supply system is described and chosen measured performance characteristics are presented. Finally, conclusions concerning the features of the tested prototype hybrid motor and possible solutions of the faced issues, during assembling and testing, are presented.

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Authors and Affiliations

Jean-Francois Rouchon
Dominique Harribey
Duc-Hoan Tran
Roland Ryndzionek
Łukasz Sienkiewicz
Mieczysław Ronkowski
Michal Michna
Grzegorz Kostro

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