Search Results

You are looking at 1 - 4 of 4 items for

  • Author: A. Robak x
Clear All Modify Search
Open access

Aleksander Robak, Michał Pieńko and Ewa Błazik-Borowa

Abstract

A few examples of scaffoldings designed, built and used in recent years in Poland have been presented here in this paper. There have been described facilities of various forms, which are surrounded by scaffoldings. This makes the design and assembly processes demand large labour input. The main focus has been set to the problems in the operation of scaffoldings used during the renovation of historic monuments. The scaffoldings used at such buildings are usually of complex and alternating geometry. In extreme cases, it is impossible to anchor the scaffolding due to the mechanical sensitivity of building facades. Other problem often affecting the operation of scaffoldings near such buildings is large inclination of roof surfaces, at which the scaffoldings are based on.

Open access

P. Jamiṅska-Gadomska, J. Bẹc, T. Lipecki and A. Robak

Abstract

This paper presents an analysis of natural vibrations of typical façade scaffolding. Three Finite Element Method models with different levels of accuracy of the real structure of the scaffolding representation were used. Modal analysis was carried out for each of these models. The obtained frequencies and mode shapes were compared with the results from the measurements performed on the full-scale scaffolding. The authors of the paper point out the difficulties arise while modelling such structures, and suggest ways to improve the accuracy of scaffolding computational models.

Open access

E. Błazik-Borowa, M. Pieńko, A. Robak, A. Borowa and P. Jamińska-Gadomska

Abstract

This paper concerns an approach to model the ledger-stand joints of modular scaffolds. Based on the analysis of the working range of the ledger (represented by a linear relationship between load and displacement), two models of the ledger-stand joint are analysed: first - with flexibility joints and second - with rigid joints and with a transition part of lower stiffness. Parameters are selected based on displacement measurements and numerical analyses of joints, then they are verified. On the basis of performed research, it can be stated that both methods of joint modelling recommended in this paper, can be applied in engineering practices.

Open access

V. Musalimov, Y. Monahov, M. Tamre, D. Rõbak, A. Sivitski, G. Aryassov and I. Penkov

Abstract

The article discusses motion of a healthy knee joint in the sagittal plane and motion of an injured knee joint supported by an active orthosis. A kinematic scheme of a mechanism for the simulation of a knee joint motion is developed and motion of healthy and injured knee joints are modelled in Matlab. Angles between links, which simulate the femur and tibia are controlled by Simulink block of Model predictive control (MPC). The results of simulation have been compared with several samples of real motion of the human knee joint obtained from motion capture systems. On the basis of these analyses and also of the analysis of the forces in human lower limbs created at motion, an active smart orthosis is developed. The orthosis design was optimized to achieve an energy saving system with sufficient anatomy, necessary reliability, easy exploitation and low cost. With the orthosis it is possible to unload the knee joint, and also partially or fully compensate muscle forces required for the bending of the lower limb.