Beam Geometry Research Articles

Effects of geometrical parameters on rarefied gas flows and Knudsen force in the system of triangular-rectangular beams with different temperatures

In the rarefied gas, the gas flows induced by the inhomogeneous temperature fields and the Knudsen force exerting on the immersed structure are potentially applicable to the micro/nano-electromechanical systems (MEMS/NEMS) and aerospace. The system composed of a series of triangle cold beams and rectangle hot beams is proposed, and the effects of the beam geometry, dimensions, and positions for different pressures on rarefied gas flows and Knudsen force are researched based on the direct simulation Monte Carlo (DSMC) method. The results reveal that both the gas flows and Knudsen force are highly sensitive to these factors. Particularly, the applications of triangular cross-section cold beams and large height-to-width ratios are necessary for a larger Knudsen force. Compared to the rectangle cold beam, when the triangle cold beam has an inclination of approximately 20°, the peak value of Knudsen force can increase by 142%. Moreover, Knudsen force monotonically reduces with the distance between the cold and hot beams increasing. However, the effects of the distance between the cold beam and substrate (substrate proximity) on Knudsen force depend on the ambient pressure. In general, an appropriate increase in substrate proximity appears to be a smart way to practically enhance the Knudsen force.

Evaluation and optimization of flexural properties of anisotropic recycled carbon fiber card web reinforced thermoplastic hollow beams

The flexural properties of hollow beams are influenced by both the structural morphologies and the level of anisotropy of the materials. Card web carbon fiber-reinforced thermoplastics (CWTs), recognized as a promising composite for fabrication with recycled carbon fiber, demonstrate control over fiber alignment and robust mechanical properties, characterized by a wide distribution of fiber lengths. In this study, square-shaped, tube-shaped, and hat-shaped hollow beams are modeled with different geometries. Calculations are performed on different input data featuring CWTs with varying fiber alignments using a modified Mori-Tanaka model, and the results are verified with experimental data. The effects of fiber alignment, beam geometries, and beam types on the flexural properties of CWT hollow beams are evaluated and compared with unidirectional (UD) carbon fiber composites, aluminum alloys, and steel beams. The highest levels of flexural stiffness and specific flexural stiffness (indicative of the most effective lightweight property) in square-shaped and tube-shaped hollow beams were observed in CWTs with higher fiber alignment. The hat-shaped beams achieved the highest level of flexural properties at a relatively lower fiber alignment level. Comparisons with 1 mm wall-thickness steel hollow beams indicated that CWTs with specific fiber alignments could achieve a weight reduction of over 50 % while maintaining the same flexural stiffness. This performance surpasses that of UD composites and aluminum alloys.

Dynamic diffraction of thermal neutrons in crystals with continuous deformation field

The purpose of the work is to consider the basics of the formation of a diffraction wave field of thermal neutrons in the case of Laue transmission geometry of a limited beam of neutrons in the crystal, taking into account the peculiarities of the interaction of thermal neutrons with a continuously and slowly changing deformation field of the crystal net. The conditions of both diffraction blurring and diffraction contraction (focusing) up to the practical restoration of the original shape of the packet will be studied.An integral form for determining the quasi-amplitudes of diffracted waves within the framework of the original spatially inhomogeneous beams is formulated, based on the constructed functions of the influence of a point source of thermal neutron waves for crystals with a continues deformation field. It has been shown that neutron focusing is effective, which is revealed by a smaller half-width of the focal spot, an increase in the resolving power of the energy spectrum and focusing efficiency.

Predictive modeling of wide-shallow RC beams shear strength considering stirrups effect using (FEM-ML) approach

This paper presents an analysis and prediction of the shear strength of wide-shallow reinforced concrete beams, utilizing Finite Element Analysis (FEA) and machine learning techniques. The methodology involves validating a detailed Finite Element Model (FEM) against experimental results, conducting a parametric study, and developing three Machine Learning prediction equations. The FEM captures concrete and steel behaviors, including cracking and crushing for concrete and linear isotropic properties for steel reinforcement. Loading and boundary conditions are defined for accuracy and validated against 13 experimental specimens, exhibiting a maximum 8% and 12% difference in loads and deflections, respectively. A parametric study generates a dataset of 77 wide beam configurations, exploring variations in beam widths, concrete strengths, compression rebars, and shear reinforcement. This dataset is used to develop machine learning models, including “Genetic Programming (GP)”, “Evolutionary Polynomial Regression (EPR)”, and “Artificial Neural Network (ANN)”. Comparative analysis reveals GP and EPR models with over 95% correlation, while the ANN model outperforms with 99% accuracy. Sensitivity analysis underscores the significant influence of concrete strength and beam aspect ratio on shear strength. In conclusion, the study demonstrates the potential of FEA and machine learning models to predict shear strength in wide-shallow reinforced concrete beams, providing valuable insights for architectural design and engineering practices and emphasizing the role of concrete strength and beam geometry in shear behavior.

Seismic design optimization of space steel frame buildings equipped with triple friction pendulum base isolators

To increase the seismic resilience of structures, it is necessary to utilize seismic isolation to increase structural periods and reduce story drifts. When seismic isolation is implemented, structures are capable of deforming by remaining within safe limits. Thus, more seismically resilient designs are achieved compared to conventional fixed-based structures since lighter structural design weights are attained. The principal aim of this study is to achieve the comparative design optimization of space steel frame buildings equipped with seismic base isolation and to examine the effect of seismic base isolation on optimum structural design weight by comparing the same structures with conventional rigid-based ones. For seismic base isolation, triple friction pendulums are implemented into steel frame buildings. For this aim, four different space steel frame buildings with 4-, 6-, 8-, and 10-story are treated as design examples. A novel design optimization algorithm is encoded, which includes nature-inspired metaheuristic artificial bee colony, crow search, and Archimedes optimization algorithms to achieve design optimizations of triple friction pendulums equipped with seismic-isolated space steel frame buildings. The practice code provisions of load and resistance factor design specification for structural steel buildings have been applied to control the structural design constraints of inter-story drift, top-story drift, strength, displacement, and connections geometry of beams and columns. Eventually, it has been remarked that seismic base isolation significantly reduces the structural optimal design weight of space steel frame buildings.

437: Two-step beam geometry optimization for VMAT gantry angles in breast treatments

437: Two-step beam geometry optimization for VMAT gantry angles in breast treatments

Topological optimization of structures with thermomechanical loading under compliance constraints for 3D printing applications

Currently, due to the high costs of production and expensive raw materials, approaches, including, making models smaller and lighter, are especially considered in the design of structures. In order to better describe the capabilities, efficiency, and limitations of an innovative field called topology optimization, various practical problems under different loadings and boundary conditions were evaluated in this study. Optimization algorithms were used in ANSYS software for the optimization of a cantilever beam under static loading, double-girder beam and a dome-shaped geometry under static and thermal loading, a hot fluid transfer tee and an engine exhaust manifold under static loading and convection heat transfer. The results showed that the reduced volume in the final models were equal to 66.29%, 52.88%, 50.05%, 51.85%, and 35.02%, respectively. Consequently, this reduced volume causes some increase in the tension, and displacement of the final model, which can adjust them according to the limitations governing the problem. Furthermore, the amount of increase in the average value of the stress in the cantilever beam, double-girder beam, and dome-shaped geometry were 88, 800, and 6 MPa, and the average amount of displacement in these samples increased by 10.2%, 200%, and 3.3%, respectively. Challenges, and manufacturability of optimized problems were investigated by 3D printing of a dome-shaped model using the FDM method, which illustrated that the output product has a suitable level of accuracy and smoothness. Subsequently, by using supporting structures, three-dimensional holes were created with proper precision in the 3D-printed sample, which satisfied the manufacturability of relatively complex models.

The accuracy of length measurements made using imaging SONAR is inversely proportional to the beamwidth

Abstract Multibeam imaging SONARs have been used for a range of measurement applications, such as measurements of fish lengths. This study aimed to quantify the accuracy of imaging SONAR systems, that varied in frequency and beam geometry, to measure the length of synthetic targets positioned perpendicularly. Blueprint Oculus imaging SONAR systems, with four different (centre) frequencies (750 kHz, 1.2 MHz, 2.1 MHz and 3 MHz), were used to measure the length of three targets of nominal lengths: 10 cm, 20 cm and at ranges between 1 and 15.5 m. The effect of beam geometry on measurement error was then examined using regression analysis. This study found that there was an overestimation of the actual length of the target for all measurements that was inversely proportional to the horizontal beamwidth. The measurement error can be reduced by normalising for beamwidth. However, the variation of measurements (i.e. the precision) was found to also increase with range, which was attributed to the increasing beam separation. It is important that the effect of beamwidth on the accuracy of target length measurements, by imaging SONARs is acknowledged in future studies. One approach to mitigating this problem, is to limit the range at which length measurements are made to a beamwidth that produces an estimated level of error that is acceptable for that study.

Experimental investigation of the shear force capacity of prismatic cross laminated timber beams

Experimental tests of Cross Laminated Timber (CLT) under in-plane beam loading conditions are presented. The influence of the element layup, the individual lamination width, and the beam overhang at the supports on the shear force capacity was investigated. All the CLT beams had the same gross cross section, and a 4-point-bending test setup was used. The experimentally determined load-bearing capacities are compared with the load-bearing capacities resulting from analytical methods proposed for structural design, focusing on shear failure in the crossing areas of flatwise bonded laminations (shear failure mode III). The test results indicate no or very small influence of the element layup and the lamination width on the shear force capacity. These results partly contradict the predictions of the proposed design methods. Of the three studied beam geometry parameters, the beam overhang at the support had the greatest influence on the load-bearing capacity.

Analytical study of linear optical properties of metal nanoparticle trimers: the impact of dipole-dipole interaction on different modes of configuration

In this study, we theoretically investigate the linear properties of a metal nanoparticle (MNP) trimer. Three identical spherical nanoparticles (NPs) whose centers are equidistantly oriented on a same straight line are considered. Using the solid core approximation for NPs and considering interaction between particles through induced electric dipoles, the motion equation of each NP conduction electrons is analytically solved. Some appropriately approximated expressions are derived for the permittivity of each NP based on a Drude-like model, allowing the clear observation of the contribution of inter-particle interaction. Depending on the orientation of the trimer axis and incident laser beam geometry (i.e., orientation of electromagnetic (EM) fields and wave vector of laser beam), three different configurations or modes are considered. The extinction efficiency of each NP as a function of wavelength is plotted, revealing that when the laser electric field is perpendicular to the symmetry axis of the trimer, it increases compared to the case of non-interactional single NP, and its plasmon resonance peak experiences a red shift. For other cases where the electric field of the laser beam is parallel to the trimer axis, the extinction efficiency of each NP decreases, and its peak shifts to the blue. In all cases, the effect of interaction on the optical properties of the middle NP is greater than on the other NPs.

Improved Spatiotemporal Resolution in Echocardiography Using Mixed Geometry Imaging Sequences.

Cardiac ultrasound seeks to image the most dynamic environment in the body-the moving heart. Many modern ultrasound imaging techniques address the tradeoff between spatial and temporal resolution using either narrow focused beams or with broad beam, synthetic aperture (SA) sequences that have been shown to suffer from motion artifacts. Retrospective encoding for conventional ultrasound sequences (REFoCUS) unifies the processing of these various geometric sequences, but the motion sensitivity of this approach has yet to be investigated. We hypothesize that a "mixed sequence" enabled by the REFoCUS method incorporating several beam geometries may better resolve cardiac motion over a wide field of view (FOV) and at a high frame rate. First, the motion sensitivity of REFoCUS was evaluated in simulation for several focused and broad transmit profiles. Focused transmissions resolve both lateral and axial motion much more effectively than broad transmissions, with performance similar to conventional beamforming techniques. Second, a mixed sequence was designed that insonifies the full field-of-view with plane wave (PW) transmissions and key moving targets with focused transmissions. This mixed sequence was tested in simulation and in vivo and was used to image the heart as well as the liver, a low-motion control. By combining a sparse PW sequence ( n=60 ) with a small group of targeted focused transmissions ( n = 10), the anterior mitral valve leaflet (AML) at its peak observed velocity was better resolved. We believe that mixed sequences have strong potential to resolve cardiac motion at clinically relevant frame rates.

Improving Energy Harvesting from Cantilever-like Structures Based on Beam Geometry

Abstract Purpose Power gain from piezoelectric harvesters depends on several parameters and one of them is to design the substructure as to increase the mechanical strain occurred in the piezoelectric material. In this study, the effect of geometrical modification of the beam on the harvested power was investigated and new geometries were offered for increased power response from cantilever type energy harvesters. Method First, the effectiveness of auxetic structures on harvested power was investigated to see the effect of the negative Poisson’s ratio on harvested power. These structures are very popular in recent years on energy harvesting applications; however, their performances were generally compared to plain structures which is not a fair comparison. Rather, in this study, their performances were compared to non-auxetic nonlinear structures as well as plain geometry. Then, three new shapes inspired by re-entrant auxetic structure were presented for increased power response, and harvested power from these structures were evaluated under different conditions. Results It was shown that the power gain from auxetic structures is very high compared to plain structures; however, this increase in power could also be achieved using a non-auxetic simple rectangular structure in some cases. On the other hand, new geometries offered in this study performed better than the auxetic and non-auxetic geometries in most cases.

Customized deformation behavior of morphing wing through reversibly assembled multi-stable metamaterials

The geometry of multi-stable metamaterials, will change by the transition from one stable state to another. Shape morphing wings consisted of multi-stable metamaterials have capability to deform as desired, attributed to the programmable mechanical properties of architectured materials. In this study, to fabricate large-scale shape morphing structures, multi-stable unit cells with reversible connections were designed, printed and assembled. The mechanical properties and deformation capability were examined for multi-stable metamaterials with different geometrical parameters (e.g. width, thickness of beams). The deformation sequence for one assembled column consisting of identical multi-stable unit cells was found unpredictable, but could be tailored into a predictable manner by slightly adjusting beam geometry. To realize the customized deformation profile, the overall design domain of shape morphing structures was discretized into independent sub-regions. By enforcing deformation on sub-regions via the precise control of mechanical actuators that fixed with corresponding columns, the assembled shape morphing structures formed the targeted deformation. Also, the deformation feasibility was also demonstrated after incorporating voids or nondeformable functional elements within the assembled metamaterials platform. This study had provided practical solution for the design and fabrication of metamaterial-based shape morphing structures, and would shed light on future innovation of morphing aircraft.

Bending-extension coupling analysis of shear deformable laminated composite curved beams with non-uniform thickness

In this paper, the boundary-based finite element method (BFEM) is developed for the bending-extension coupling analysis of shear deformable laminated composite curved beams with non-uniform thickness. The curved beams are discretized into a series of uniform straight segments. Based upon the first order shear deformation theory and the reciprocal theorem of Betti and Rayleigh, the boundary integral equations (BIEs) associated with each beam segment are derived and expressed in explicit form. The fundamental solutions required in the BIEs are obtained explicitly from the associated Green’s function. Since no singular integrals, numerical integrations and function interpolations are involved in the BIEs, our proposed BFEM provides an exact solution for a straight beam with uniform thickness, and only one single element with two end nodes is required for our analysis. Even only an approximate solution is provided for a curved beam with non-uniform thickness, BFEM converges faster than the conventional finite element method, and the results are in well agreement with those obtained by the commercial finite element software. Through the illustrated numerical examples, its generality is shown by: (1) stacking sequence of laminates: symmetric or unsymmetric; (2) beam geometries: straight, stepped, or curvilinear with uniform or non-uniform thickness; (3) loading types: axial force, transverse force and/or bending moment; distributed or concentrated; and (4) supporting conditions: clamped, simply supported, or free; with or without internal supports.

Possible Geometries for Precast Concrete Structures, through Discussing New Connections, Robotic Manufacturing and Re-Utilisation of the Concrete Elements

This study explores the potential use of new connections to shape precast building geometries, focusing on connection performance, robotic fabrication, and foldable structural elements. Three connection types, including coupled-bolts, hinges, and steel tubes, were initially proposed and assessed in beam and portal frame geometries. In contrast, the study introduces conceptual ideas; initial experimental and numerical studies were conducted to estimate connection capacities. Robotic fabrication for connecting elements to reused concrete and converting floor elements into beams was detailed, showcasing robotic technology’s performance and potential. These connections were employed in designing new precast element geometries, ranging from simple beams to multi-story buildings. Geometric properties and volume quantities of folded and opened geometries were studied using 37 CAD models. To properly discuss the joint performance reference, monolithic elements with exact dimensions were created for comparison. Despite varied connection capacity (38% to 100%), the steel tube exhibited the most desirable performance, resembling a monolithic element with an exact size. Some proposed foldable geometries showed a significant reduction (up to 7%) in element dimensions to facilitate transport and construction.

Ultra-hypofractionated prostate cancer radiotherapy: Dosimetric impact of real-time intrafraction prostate motion and daily anatomical changes

PurposeTo retrospectively assess the differences between planned and delivered dose during ultra-hypofractionated (UHF) prostate cancer treatments, by evaluating the dosimetric impact of daily anatomical variations alone, and in combination with prostate intrafraction motion. MethodsProstate intrafraction motion was recorded with a transperineal ultrasound probe in 15 patients treated by UHF radiotherapy (36.25 Gy/5 fractions). The dosimetric objective was to cover 99 % of the clinical target volume with the 100 % prescription isodose line. After treatment, planning CT (pCT) images were deformably registered onto daily Cone Beam CT to generate pseudo-CT for dose accumulation (accumulated CT, aCT). The interplay effect was accounted by synchronizing prostatic shifts and beam geometry. Finally, the shifted dose maps were accumulated (moved-accumulated CT, maCT). ResultsNo significant change in daily CTV volumes was observed. Conversely, CTV V100% was 98.2 ± 0.8 % and 94.7 ± 2.6 % on aCT and maCT, respectively, compared with 99.5 ± 0.2 % on pCT (p < 0.0001). Bladder volume was smaller than planned in 76 % of fractions and D5cc was 33.8 ± 3.2 Gy and 34.4 ± 3.4 Gy on aCT (p = 0.02) and maCT (p = 0.01) compared with the pCT (36.0 ± 1.1 Gy). The rectum was smaller than planned in 50.3 % of fractions, but the dosimetric differences were not statistically significant, except for D1cc, found smaller on the maCT (33.2 ± 3.2 Gy, p = 0.02) compared with the pCT (35.3 ± 0.7 Gy). ConclusionsAnatomical variations and prostate movements had more important dosimetric impact than anatomical variations alone, although, in some cases, the two phenomena compensated. Therefore, an efficient IGRT protocol is required for treatment implementation to reduce setup errors and control intrafraction motion.

Resultados experimentais e análise de carga limite pelo Método de Bielas e Tirantes (MBT) de vigas-parede com entalhes e aberturas

Abstract This article presents experimental results of eight non-aligned, non-geometrically symmetrical deep beams with notches and openings. The variables considered in the study were the presence of web reinforcement, and the geometry of the deep beams. Along with the experimental investigation, a study of strut-and-tie models (STM) representing the behavior (failure mode and maximum load) of reinforced concrete deep beams with complex geometries was performed. The experimental results showed that the ultimate load capacity of deep beams is significantly affected by the presence of reinforcement in the web. Furthermore, the study showed that the STM is conservative and tends to underestimate the results, reducing its ability to predict failure load.

Design analysis and simulation of serpentine-shaped piezoelectric cantilever beam for pipeline vibration-based energy harvester

&lt;abstract&gt; &lt;p&gt;This study investigated the design and simulation of a novel serpentine-shaped piezoelectric cantilever beam to harness pipeline vibration energy. As the demand for sustainable energy sources increases, harvesting piezoelectric energy from environmental vibrations offers an attractive way to use low-power devices. The purpose of the proposed serpentine configuration is to improve energy dissipation efficiency by maximizing the piezoelectric material exposure to dynamic mechanical stress caused by pipeline vibration. The design process included finite element analysis simulations performed using COMSOL Multiphysics software to optimize the geometry of the cantilever beam. The serpentine structure was strategically designed to take advantage of the flexural vibration caused by the pipeline and its operating dynamics. Extensive simulations evaluated the piezoelectric cantilever beam, taking into account various parameters such as beam size, shape and material properties. From the analysis conducted in COMSOL Multiphysics software, the model was able to produce up to 14.38 V at the resonant frequency of 263 Hz. The simulation results show the effectiveness of the serpentine-shaped piezoelectric cantilever in generating electrical energy from the pipeline vibrations within the safe vibration region of the pipeline from 10 to 300 Hz.&lt;/p&gt; &lt;/abstract&gt;

Learning algorithms for identification of whisky using portable Raman spectroscopy

Reliable identification of high-value products such as whisky is vital due to rising issues of brand substitution and quality control in the industry. We have developed a novel framework that can perform whisky analysis directly from raw spectral data with no human intervention by integrating machine learning models with a portable Raman device. We demonstrate that machine learning models can achieve over 99% accuracy in brand or product identification across twenty-eight commercial samples. To demonstrate the flexibility of this approach, we utilized the same algorithms to quantify ethanol concentrations, as well as measuring methanol levels in spiked whisky samples. To demonstrate the potential use of these algorithms in a real-world environment we tested our algorithms on spectral measurements performed through the original whisky bottle. Through the bottle measurements are facilitated by a beam geometry hitherto not applied to whisky brand identification in conjunction with machine learning. Removing the need for decanting greatly enhances the practicality and commercial potential of this technique, enabling its use in detecting counterfeit or adulterated spirits and other high-value liquids. The techniques established in this paper aim to function as a rapid and non-destructive initial screening mechanism for detecting falsified and tampered spirits, complementing more comprehensive and stringent analytical methods.

Laser induced temperature-jump time resolved IR spectroscopy of zeolites.

Combining pulsed laser heating and time-resolved infrared (TR-IR) absorption spectroscopy provides a means of initiating and studying thermally activated chemical reactions and diffusion processes in heterogeneous catalysts on timescales from nanoseconds to seconds. To this end, we investigated single pulse and burst laser heating in zeolite catalysts under realistic conditions using TR-IR spectroscopy. 1 ns, 70 μJ, 2.8 μm laser pulses from a Nd:YAG-pumped optical parametric oscillator were observed to induce temperature-jumps (T-jumps) in zeolite pellets in nanoseconds, with the sample cooling over 1-3 ms. By adopting a tightly focused beam geometry, T-jumps as large as 145 °C from the starting temperature were achieved, demonstrated through comparison of the TR-IR spectra with temperature dependent IR absorption spectra and three dimensional heat transfer modelling using realistic experimental parameters. The simulations provide a detailed understanding of the temperature distribution within the sample and its evolution over the cooling period, which we observe to be bi-exponential. These results provide foundations for determining the magnitude of a T-jump in a catalyst/adsorbate system from its absorption spectrum and physical properties, and for applying T-jump TR-IR spectroscopy to the study of reactive chemistry in heterogeneous catalysts.