FEATURES OF THE STRAIN-STRESS STATE OF BEAMS WITH A CORRUGATED WALL OF VARIABLE RIGIDITY

Corrugated steel beams represent a promising area of research in the fi eld of structural engineering today. The article studies the behavior of a metal beam with a corrugated wall of an I-profi le under bending conditions. Beam considered span of 12 m. A fi nite element model of the calculated structure was built in the LIRA-SAPR software package. The analysis of the stress-strain state of a corrugated beam of variable stiff ness, which has a fl at fragment in the central part of the wall, is carried out. The beam thus obtained has a number of advantages over beams with only a fl at or fully corrugated wall. The conclusions based on the results of the analysis of the calculation are presented.

Study of a magnetic SMA-based energy harvester using a corrugated structure

In recent years demand for mobile electrical power has been increased and due to this application, energy harvester systems have been developed to convert mechanical energy into electrical energy using smart materials. In this investigation, a novel arrangement of an energy harvester using Magnetic Shape Memory Alloys (MSMAs) is developed. Elements of MSMA are attached to a corrugated beam and their roots are fixed. The way of harvesting energy from this system is based on conversion of vibration motion energy to the magnetic flux gradient. There is a number of copper coils that wrapped around the MSMA elements in a constant magnetic field. If strain or stress field is applied to the MSMA elements, the electrical current is induced to coils. The problem is studied with analytical methods, and for this purpose, MATLAB solver is used. To simulate the behavior of MSMA substance Kiefer and Lagoudas nonlinear model is used. To verify the results, these two arrangements have been analyzed in ABAQUS. To provide the material properties of MSMA elements, UMAT code has been used. It will be shown that size of this MSMA based energy harvester can become smaller with using corrugated beam structure instead of simple cantilever beam.

Natural Frequencies and Band Gaps of Periodically Corrugated Beams

Structures with geometric periodicity can present interesting dynamic properties like stop and pass frequency bands. In this case, the geometric periodicity has the effect of filtering the propagating waves in the structure, in a similar way to that of phononic crystals and metamaterials (non-homogeneous materials). Hence, by adopting such structures, we can design systems that present dynamic characteristics of interest, e.g., with minimum dynamic response in a given frequency range with large bandwidth. In the present work, we show that corrugated beams also present the dynamic properties of periodic structures due to their periodic geometry only (no need of changing mass or material properties along the beam). Two types of corrugated beams are studied analytically: beams with curved bumps of constant radii and beams with bumps composed of straight segments. The results show that, as we change the proportions of the bump, the natural frequencies change and tend to form large band gaps in the frequency spectrum of the beam. Such shifting of the natural frequencies is related to the coupling between longitudinal and transverse waves in the curved beam. The results also show that it is possible to predict the position and the limits of the first band gap (at least) as a function of the fundamental frequency of the straight beam (without bumps), irrespective of the total length of the corrugated beam.

IMPROVING CONSTRUCTIVE SOLUTION OF BEAM WITH CORRUGATED WALL

The analysis of improving ways to test for load-bearing structures - metal beams with corrugated wall was conducted. Weak places, limiting their load-bearing capacity were determined. It was found that the criterion for determining the carrying capacity of thin-walled corrugated beam is its local resistance. The author's solution to increase the local stability of the corrugated wall beams was suggested. Author's solution is to give the corrugated wall of further extruded profile of different geometry. The influence of the shape and size of punching the wall on the carrying capacity of corrugated beams was determined. The studies confirming the effectiveness of the proposed constructive solutions increase the stability of the corrugated wall are conducted. Preliminary assessment of the degree of increase of the bearing capacity of the beam by punching its wall is obtained.