Shape functions for high-order shear deformation beam element

In this article, shape functions for higher-order shear deformation beam theory are derived. For the two nodded beam element, transverse deflection is assumed as cubic polynomial. By using equations of equilibrium of high-order theory that are already derived by J. N. Reddy in 1997, equation for slope of high- order theory is found. Finally with the boundary conditions of beam element and assumed kinematics of high-order theory, shape functions are derived.

Visualizing the strongly reshaped skyrmion Hall effect in multilayer wire devices

Magnetic skyrmions are nanoscale spin textures touted as next-generation computing elements. When subjected to lateral currents, skyrmions move at considerable speeds. Their topological charge results in an additional transverse deflection known as the skyrmion Hall effect (SkHE). While promising, their dynamic phenomenology with current, skyrmion size, geometric effects and disorder remain to be established. Here we report on the ensemble dynamics of individual skyrmions forming dense arrays in Pt/Co/MgO wires by examining over 20,000 instances of motion across currents and fields. The skyrmion speed reaches 24 m/s in the plastic flow regime and is surprisingly robust to positional and size variations. Meanwhile, the SkHE saturates at ∼22∘, is substantially reshaped by the wire edge, and crucially increases weakly with skyrmion size. Particle model simulations suggest that the SkHE size dependence — contrary to analytical predictions — arises from the interplay of intrinsic and pinning-driven effects. These results establish a robust framework to harness SkHE and achieve high-throughput skyrmion motion in wire devices.

METHODOLOGY FOR CONDUCTING VIRTUAL TESTS BY CREATING A FINITE ELEMENT MODEL

In this paper, we formulated the concept of the process of hitting a car on a fence as a movement along a curved trajectory with a certain radius of curvature. Special attention was paid to the contact of parts of different stiffness (when modeling the fence, these are ground-stand contacts), since the stiffness of the spring added to the contacting surfaces directly depends on the stiffness of the bodies being contacted. When soft bodies contact, its rigidity may be small, which can lead to instability of the solution. Also, the critical deflection of the fence (the transverse deflection of the fence, equal to twice the value of the console departure), after which the beam is inevitably lowered along with the deviated posts and the vehicles move over the fence.

Eco-localization of a prey in a spider orb web

Orb web spiders locate the position of a perturbation in the web because of a prey impact through highly sensitive slit sensilla at the tip of their legs. Thus, the web serves as a self-made extension of its sensory space which transmits vibrations from the perturbation point to the spider location. These vibrations may contain the information required by the spider to rapidly identify the position where the prey has impacted and approach to it before it flies away. For axially symmetric orb webs supported at the boundary and for a spider which stays at the center of the web, it was shown that the knowledge of the transverse deflection time history at the eight spider legs, for a sufficiently large interval of time, contains enough information to localize the position of the prey. In this article, we address the same inverse problem of localization of the prey, but we suppose that the spider knows only a small number of selected information of the transverse displacement, such as, for example, the maxima of the response of the time history at the eight control points. We show how this reduced information still allows the spider to obtain a fairly accurate angular localization of the prey, for different prey and orb web characteristics.

Experimental demonstration of novel beam characterization using a polarizable X-band transverse deflection structure

The PolariX TDS (Polarizable X-Band Transverse Deflection Structure) is an innovative TDS-design operating in the X-band frequency-range. The design gives full control of the streaking plane, which can be tuned in order to characterize the projections of the beam distribution onto arbitrary transverse axes. This novel feature opens up new opportunities for detailed characterization of the electron beam. In this paper we present first measurements of the Polarix TDS at the FLASHForward beamline at DESY, including three-dimensional reconstruction of the charge-density distribution of the bunch and slice emittance measurements in both transverse directions. The experimental results open the path toward novel and more extensive beam characterization in the direction of multi-dimensional-beam-phase-space reconstruction.

Skyrmion ratchet propagation: utilizing the skyrmion Hall effect in AC racetrack storage devices

Magnetic skyrmions are whirl-like nano-objects with topological protection. When driven by direct currents, skyrmions move but experience a transverse deflection. This so-called skyrmion Hall effect is often regarded a drawback for memory applications. Herein, we show that this unique effect can also be favorable for spintronic applications: We show that in a racetrack with a broken inversion symmetry, the skyrmion Hall effect allows to translate an alternating current into a directed motion along the track, like in a ratchet. We analyze several modes of the ratchet mechanism and show that it is unique for topological magnetic whirls. We elaborate on the fundamental differences compared to the motion of topologically trivial magnetic objects, as well as classical particles driven by periodic forces. Depending on the exact racetrack geometry, the ratchet mechanism can be soft or strict. In the latter case, the skyrmion propagates close to the efficiency maximum.

Mechanical Properties of New Composite Wood-Plastic Formworks with Aluminum Alloy Frame

Formwork engineering plays a crucial role in cost, efficiency, quality, and schedule in civil engineering. Currently, wood-plastic formwork, which has favorable mechanical properties such as wood and excellent stability, formability, ease of demolding, and time-saving as plastic, is earning its increasing reputation in construction. This work focuses on mechanical properties of two types of new composite wood-plastic formworks with aluminum alloy frame used for construction, that is, single-span simply supported and three-span continuous formworks. Experimental investigation shows that the two types of wood-plastic formworks demonstrate favorable performance, and the deflections and stresses are within the allowable range, thereby satisfying the structural bearing requirements. Numerical analyses confirm that the results of the refined and general finite element models are consistent with the experimental results, but the former has a higher accuracy. When the requirement of accuracy is not too strict, the general model is preferred, given the modeling convenience and high efficiency. On the basis of experimental and numerical investigations, practical simplified formulas are proposed to facilitate rapid calculation and evaluation considering transverse deflection and inconsistency of two materials. Therefore, the results in this work can provide a theoretical basis for developing and applying the new formworks.

Effect of Axial Porosities on Flexomagnetic Response of In-Plane Compressed Piezomagnetic Nanobeams

We investigated the stability of an axially loaded Euler–Bernoulli porous nanobeam considering the flexomagnetic material properties. The flexomagneticity relates to the magnetization with strain gradients. Here we assume both piezomagnetic and flexomagnetic phenomena are coupled simultaneously with elastic relations in an inverse magnetization. Similar to flexoelectricity, the flexomagneticity is a size-dependent property. Therefore, its effect is more pronounced at small scales. We merge the stability equation with a nonlocal model of the strain gradient elasticity. The Navier sinusoidal transverse deflection is employed to attain the critical buckling load. Furthermore, different types of axial symmetric and asymmetric porosity distributions are studied. It was revealed that regardless of the high magnetic field, one can realize the flexomagnetic effect at a small scale. We demonstrate as well that for the larger thicknesses a difference between responses of piezomagnetic and piezo-flexomagnetic nanobeams would not be significant.

Free Vibration of Bistable Clamped–Clamped Beams: Modeling and Experiment

Bistable clamped–clamped beams have been used in a wide range of applications such as switches, resonators, energy harvesting, and vibration reduction. Most studies on this classic buckling problem focus on obtaining either the static configuration and the required critical axial load or the natural frequencies and mode shapes of postbuckling vibrations analytically. In this article, we present our study including analytical modeling and experimental method on bistable clamped–clamped beams, aiming to understand the detailed snap-through process and the ensuing vibration. In the analytical model, by decomposing the transverse deflection into static buckling configuration and linear vibration, we obtain the natural frequencies and mode shapes for the buckled beam and investigate the effects of static deflection on the symmetric and antisymmetric modes. An experimental design using noncontact methods is implemented to directly measure the response of the whole beam in the snap-through process and the sound generated by the vibrating beam. The measurements are characterized in both time and frequency domain and found to be in good agreement with the analytical model. The study presented in this article enhances the fundamental understanding of the classical problem of bistable clamped–clamped beams.