Cantilever Beam with a Single Fiber Bragg Grating to Measure Temperature and Transversal Force Simultaneously

This work investigates a new interrogation method of a fiber Bragg grating (FBG) sensor based on longer and shorter wavelengths to distinguish between transversal forces and temperature variations. Calibration experiments were carried out to examine the sensor’s repeatability in response to the transversal forces and temperature changes. An automated calibration system was developed for the sensor’s characterization, calibration, and repeatability testing. Experimental results showed that the FBG sensor can provide sensor repeatability of 13.21 pm and 17.015 pm for longer and shorter wavelengths, respectively. The obtained calibration coefficients expressed in the linear model using the matrix enabled the sensor to provide accurate predictions for both measurements. Analysis of the calibration and experiment results implied improvements for future work. Overall, the new interrogation method demonstrated the potential to employ the FBG sensing technique where discrimination between two/three measurands is needed.

Effects of the passive electromagnetic damper on the behavior of a fluid-conveying pipeline

This paper studies the passive electromagnetic damper effects on the behavior of a pipeline conveying fluid. In this work, a uniform cantilever Euler–Bernoulli beam, a follower force, and a transversal force are utilized for modeling of the pipe, fluid force, and electromagnetic damping force, respectively. The passive electromagnetic damper includes a permanent-magnet DC motor, a ball screw, and a nut. The most important purpose of this study is first to decrease the pipe vibration amplitude resulting from the fluid velocity and then transform the dissipated energy into the electric energy. To achieve this goal, the stability and vibration of the model were investigated using Ritz and Newmark methods. The effects of the electromagnetic damper characteristics on the critical velocity were considered first, and then the energy storage of the passive electromagnetic damper was inspected. The results of simulation showed that the passive electromagnetic damper can simultaneously reduce the pipeline vibration and store energy up to 4.3 [mW] for low fluid flow velocity.

Transversal Pressure Effect in Circulative Separators

Progressive urban development of the human environment requires new methods of rain water treatment. Recently, there has been a growing interest in the improvement of gravitational suspension separation, and especially in the application of the centrifugal force. This important factor can be induced in two ways; by the circulation of the reservoir containing the fluid (centrifugal separators), or by a tangent supply of this reservoir (circulative separators). In addition to the centrifugal force, another essential transversal force is at work in this case, resulting from the local variability of the pressure. In the literature, this force is derived for centrifuge conditions, but applied also to circulative separators, which is questionable, as in the latter devices velocity and pressure fields are clearly different. The paper is devoted to the determination of the transversal pressure effect in circulative separators. First, a model of tangent and radial velocity profiles is introduced. The radial pressure distribution, calculated on this basis and verified experimentally, leads to the final result, that is, a technical formula describing the force in question

Spinning rough disc moving in a rarefied medium

We study the Magnus effect: deflection of the trajectory of a spinning body moving in a gas. It is well known that in rarefied gases, the inverse Magnus effect takes place, which means that the transversal component of the force acting on the body has opposite signs in sparse and relatively dense gases. The existing works derive the inverse effect from non-elastic interaction of gas particles with the body. We propose another (complementary) mechanism of creating the transversal force owing to multiple collisions of particles in cavities of the body surface. We limit ourselves to the two-dimensional case of a rough disc moving through a zero-temperature medium on the plane, where reflections of the particles from the body are elastic and mutual interaction of the particles is neglected. We represent the force acting on the disc and the moment of this force as functionals depending on ‘shape of the roughness’, and determine the set of all admissible forces. The disc trajectory is determined for several simple cases. The study is made by means of billiard theory, Monge–Kantorovich optimal mass transport and by numerical methods.

EVALUATION OF TRANSVERSAL FORCE INFLUENCE IN LAYERS OF REINFORCED CONCRETE WITH SURVIVAL MOULDS/SLUOKSNIUOTŲJŲ GELŽBETONINIŲ KONSTRUKCIJŲ SU LIKTINIAIS KLOJINIAIS STIPRUMO SKERSINIŲ JĖGŲ ATŽVILGIU ĮVERTINIMAS

Bending composite reinforced concrete slabs have horizontal concreting joints and this is their main difference from monolithic constructions. During initial bending stage of loaded composition slab compression and shear stresses appear, therefore they should be treated as monolithic ones. Nevertheless, with the augmentation of deflection the influence of transversal forces increases. Depending on the distance between concentrated force and support force, corresponding shear stresses are caused in the contact zone of the layered slab. Vector trajectories of those stresses correspond to the curve of compression layers in imaginary internal arches. The distance between the support and shear force, and the number of repetitive static heights (a=1…2…5d) of the slab have been evaluated, some cases have been observed and noted when forces influencing the detachment of monolithic and precast slab are the greatest ones. It has been noticed that the augmentation of distance between the support and vertical force causes the decrease of leaning angle of successive shear stresses in reinforcement bars.