Flexural Response and Failure Analysis of Solid and Hollow Core Concrete Beams with Additional Opening at Different Locations

It is essential to make openings in structural concrete elements to accommodate mechanical and electrical needs. To study the effect of these openings on the performance of reinforced concrete (RC) elements, a numerical investigation was performed and validated using previous experimental work. The effect of the position and dimension of the opening and the beam length on the response of the beams, loads capacities, and failure modes was studied. The simulated RC beams showed different responses, loads capacities, and failure modes depending on the position and dimension of the opening. The transversal near support opening (TNSH) and longitudinal holes (LH) showed lower effects on the load capacities of the beams than the transversal near center opening (TNCH). The supreme reduction percentages of the load capacity (µu%) for beams with TNCH and TNSH were 37.21% and 30.34%, respectively (opening size = 150 × 150 mm2). In addition, the maximum µu% for beam with LH was 17.82% (opening size = 25% of the beam size). The TNSH with a width of less than 18.18% of the beam shear span (550 mm) had trivial effects on the beam’s load capacities (the maximum µu% = 1.26%). Although the beams with combined LH and TNCH or LH and TNSH showed different failure modes, they experienced nearly the same load reductions. Moreover, the length of the beam (solid or hollow) had a great effect on its failure mode and load capacity. Finally, equations were proposed and validated to calculate the yield load and post-cracking deflection for the concrete beams with a longitudinal opening.

An Ultrahigh-Sensitivity Graphene Resonant Gyroscope

In this study, a graphene beam was selected as a sensing element and used to form a graphene resonant gyroscope structure with direct frequency output and ultrahigh sensitivity. The structure of the graphene resonator gyroscope was simulated using the ANSYS finite element software, and the influence of the length, width, and thickness of the graphene resonant beam on the angular velocity sensitivity was studied. The simulation results show that the resonant frequency of the graphene resonant beam decreased with increasing the beam length and thickness, while the width had a negligible effect. The fundamental frequency of the designed graphene resonator gyroscope was more than 20 MHz, and the sensitivity of the angular velocity was able to reach 22,990 Hz/°/h. This work is of great significance for applications in environments that require high sensitivity to extremely weak angular velocity variation.

Architectural tunability of mechanical metamaterials in the nanometer range

Mechanical metamaterials can exhibit extraordinary mechanical properties due to a specific architecture rather than the base material. When the structural dimensions reach the sub-micrometer range, such micro- and nanolattices may also benefit from size-affected mechanical properties. However, well-defined geometric adjustments on this length scale are limited by the resolution limits of the underlying manufacturing technology. Here, we used a 3D direct laser writing (3D-DLW) process with integrated laser power variation to fabricate polymeric microlattices, which were then pyrolized to obtain glassy carbon structures. The laser power was varied by a quadratic function along the beams from one node to another over the length of a unit cell, thus enabling geometric adjustments in the range of a few nanometers. Rounded and notch-like joints were realized by increased and reduced laser power at the nodes, respectively. Furthermore, the beam cross section was varied along the beam length, thereby creating convex or concave beam shapes. A laser power variation opens up new design possibilities for micro- and nanolattices in the sub-micrometer range by overcoming process related limitations.

PRODUCTIVE QUALITIES OF MARAL STAGS OF NOVOTALITSK LINE OF ALTAI-SAYAN BREED

Antlers are the main product obtained from marals. The problem of increasing antler production in maral breeding remains relevant. Purpose of the research is analysis of antler productivity of first-antler stags and stags of marals of Novotalitsk line of Altai-Sayan breed. The work was carried out on the maral farms of OS Novotalitskoye Department of Federal State Budgetary Scientific Institution “Federal Altai Scientific Center of Agrobiotechnologies during the antler-cutting campaign from May to July 2020. A total of 1661 animals were valued, including 266 first-antler stags. The most marals are at the age from 2 to 8 years old, the most numerous is the group of first-antler stags (16%). The average antler productivity per one first-antler stag is 1.5 kg, per one stag - 5.2 kg. The antlers of the first-antler stags are characterized by the following parametric data: beam length - 35.8 ± 0.41 cm, beam girth - 12.4 ± 0.08 cm, supraorbital process length - 16.1 ± 0.30 cm, ice process length - 15 , 0 ± 0.36 cm, the length of the middle process is 11.1 ± 0.32 cm, the depth of the split is 1.9 ± 0.07 cm. As for stags, the beam length is 55.7 ± 0.30 cm, the beam girth is 16 , 5 ± 0.07 cm, the length of the supraorbital process is 27.6 ± 0.18 cm, the length of the ice process is 29.6 ± 0.25 cm, the length of the middle process is 23.4 ± 0.21 cm, the split depth is 5.5 ± 0.13 cm. The marals have the following crown shapes: fork, shovel, goblet-like, round, triplet, boot. The most common form is the fork, the highest productivity in the herd is shown by marals with a goblet-like crown of antlers (7.1 ± 0.35 kg).

An Electrostatic Self-Excited Resonator with Pre-Tension/Pre-Compression Constraint for Active Rotation Control

We report a novel electrostatic self-excited resonator driven by DC voltage that achieves variable velocity-position characteristics via applying the pre-tension/pre-compression constraint. The resonator consists of a simply supported micro-beam, two plate electrodes, and two adjustable constraint bases, and it can be under pre-compression or pre-tension constraint by adjusting the distance L between two constraint bases (when beam length l > L, the resonator is under pre-compression and when l < L, it is under pre-tension). The oscillating velocity of the beam reaches the maximum value in the position around electrodes under the pre-compression constraint and reaches the maximum value in the middle position between two electrodes under the pre-tension condition. By changing the constraint of the microbeam, the position of the maximum velocity output of the oscillating beam can be controlled. The electrostatic self-excited resonator with a simple constraint structure under DC voltage has great potential in the field of propulsion of micro-robots, such as active rotation control of flapping wings.

Performance Evaluation of a Vortex Induced Piezoelectric Energy Converter (VIPEC) with CFD Approach

A novel vortex induced piezoelectric energy converter (VIPEC) was present in this paper to harvest flow kinetic energy from the ambient environment through a piezoelectric beam. The converter consists of a circular cylinder, a pivoted beam attached to the tail of the cylinder and several piezoelectric patches. Vortex induced pressure difference acts on the beam and drives the beam to squeeze piezo patches to convert fluid dynamic energy into electric energy. Transition Shear Stress Transport (SST) combined with Scale Adaptive Simulation (SAS) model was employed to predict the turbulent flow and flow separation around the cylinder with various beam lengths at high Reynolds number of 8 × 104 based on the computational fluid dynamics (CFD) approach. The accuracy of SST-SAS model was investigated through verification and validation studies. The output voltage equation was derived from the piezoelectric constitutive equation. It was revealed that the beam length influences the flow wake pattern, the separation angle and shedding frequency greatly through changing the adverse pressure gradient around the cylinder. The wake pattern becomes symmetrical about the beam when the beam length is longer than a critical value. The length of the beam has little influence on the separation angle. When the beam length is about 1.3 times the diameter of the cylinder, the shedding frequency and output voltage achieves its maximum, and the separation angle is minimal. Maximal output voltage reaches 20 mV.

Analisis Numerik Kuat Lentur Balok Support Beam Curve Tile Beton Semi Pracetak Dengan Variasi Panjang Bentangan

Semi precast slab is a combination of precast concrete which consist of the support beam and curve tile with the cast in place concrete. During the working process, support beam will support the entire load until the slab becomes solid. The study aims to identify the effect of using variations of support beam length towards deflection-load relationship, moment-curvature, crack pattern and cross-sectional dimensions caused by pure bending moments with the same maximum load. The variations of the support beam length are L = 3000 mm, L = 4000 mm, L = 5000 mm and L = 6000 mm which can affect the cross-sectional dimensions of the support beam. The method used in this study was the numerical method by using Abaqus 6.14 CAE software. Abaqus is one of the finite element analysis (FEA) programs to model and analysis the elements of the structure. The loading applied was an axial load which has increased until the support beam failed. The numerical analysis results are the increase of cross section dimension as the increasing of support beam length. The cross-sectional dimension are 100 mm x 60 mm; 110 mm x 65 mm; 110 mm x 70 mm; and 115 mm x 75 mm. The maximum load (Pmaks) was relative same while the support beam length increased are 1,52 kN; 1,53 kN; 1,53 kN and 1,55 kN. The collapse pattern on the support beam was a pure bending crack at the most significant bending moment region. The crack pattern showed the crack on the pull side of the beam in the direction of the stirrups.Semi precast slab is a combination of precast concrete which consist of the support beam and curve tile with the cast in place concrete. During the working process, support beam will support the entire load until the slab becomes solid. The study aims to identify the effect of using variations of support beam length towards deflection-load relationship, moment-curvature, crack pattern and cross-sectional dimensions caused by pure bending moments with the same maximum load. The variations of the support beam length are L = 3000 mm, L = 4000 mm, L = 5000 mm and L = 6000 mm which can affect the cross-sectional dimensions of the support beam. The method used in this study was the numerical method by using Abaqus 6.14 CAE software. Abaqus is one of the finite element analysis (FEA) programs to model and analysis the elements of the structure. The loading applied was an axial load which has increased until the support beam failed. The numerical analysis results are the increase of cross section dimension as the increasing of support beam length. The cross-sectional dimension are 100 mm x 60 mm; 110 mm x 65 mm; 110 mm x 70 mm; and 115 mm x 75 mm. The maximum load (Pmaks) was relative same while the support beam length increased are 1,52 kN; 1,53 kN; 1,53 kN and 1,55 kN. The collapse pattern on the support beam was a pure bending crack at the most significant bending moment region. The crack pattern showed the crack on the pull side of the beam in the direction of the stirrups.