Plate Angle Research Articles

Design of Torsion Plate Energy-Absorbing Member and Analysis of Energy-Absorbing and Anti-Impact Characteristics

In order to effectively improve the impact resistance performance of the roadway anti-impact hydraulic support and reduce the loss caused by rock burst to a certain extent, a torsion plate energy-absorbing member was designed for using with the hydraulic column. By using theoretical analysis and numerical simulation methods and combining them with the parameters of the energy-absorbing characteristics evaluation index, single-factor tests were designed. Under the premise of constant impact velocity, the influence law of torsion angle, plate thickness, and fillet radius of the pressure plate on the energy-absorbing and anti-impact characteristics of energy-absorbing members were analysed. The results show that the deformation process and resistance trend of the torsion plate correspond to energy absorption. The resistance stability is high in the reaction force platform stage, and the energy increases linearly. With the increase of the torsion angle, the mean value of the reaction force increases, the fluctuation of the reaction force platform stage becomes more obvious, the specific energy absorption increases linearly, and the standard deviation reaches the minimum at 480°. Both the tensile length and the length of the reaction force platform stage increase continuously. With the increase of the plate thickness, the flatness of the torsion plate shows a trend of bad-good-bad, the mean value of the reaction force gradually increases, the specific energy absorption grows faster and then slower, and the tensile length and the length of the reaction force platform stage increase accordingly. With the increase of the fillet radius, the flatness of the torsion plate is better and the reaction force has a small improvement. The fluctuation of reaction force is most significant when the fillet radius is 2 mm, and the energy-absorbing member has the largest swing. The specific energy absorption is highest when the fillet radius is 2.5 mm, the standard deviation shows a tendency to develop firstly decreasing and then stabilising, the tensile length of the torsion plate decreases slightly, and the length of the reaction force platform firstly increases and then tends to stabilise. The torsion plate energy-absorbing member is a more ideal energy-absorbing and anti-impact member, which plays a positive role in the energy-absorbing and anti-impact of the hydraulic support.

Effect of Rayleigh backscattering on the multiwavelength random fiber laser bandwidth

We investigated the effect of Rayleigh backscattering on the bandwidth of a multiwavelength random fiber laser (MWRFL). This MWRFL is based on an erbium-doped fiber amplifier (EDFA) as the gain medium and a Lyot filter as the wavelength-selective device. A high number and stable lasing line is generated with the assistance of a nonlinear polarization rotation effect induced by highly nonlinear fiber (HNLF) and optimized by a polarization controller. Longer single-mode fiber (SMF) produces wider multiwavelength bandwidth as compared to shorter SMF lengths, as 10 km, 3 km, and 0.1 km obtained 6.24 nm, 5.76 nm, and 2.75 nm wavelength bandwidth, respectively. When the SMF is removed from the setup, no Rayleigh backscattering is provided in the cavity, which led to a narrower multiwavelength bandwidth of 2.69 nm. Subsequently, the alteration of EDFA power, half-wave plate (HWP) angle, and quarter-wave plate (QWP) angles affected the degradation of multiwavelength performance. The best output spectrum is achieved at an EDFA power of 18 dBm, a HWP angle of 60°, and a QWP angle of 105°. The laser stability over a period of 120 min was excellent with a peak power deviation of 1.33 dB.

Cutout effects on the dynamic analysis of laminated composite plates resting on two-parameter elastic foundation

This paper investigates the free vibration analysis of cutout laminated composite plates resting on an elastic foundation of the Winkler and Pasternak type. An efficient isoparametric 9-noded Lagrangean C0 finite element method is developed based on five degrees of freedom (d.o.f) first-order shear deformation theory (FSDT), which has the benefit of the requirement of only one variable along the thickness to model the plate equations to obtain the numerical results from the formulation. The equation of motion of the plate is derived using the virtual work principle. The accuracy and efficiency of the current formulation are validated with established results concerning free vibration analysis of laminated composite plates on elastic foundations and plates containing cutouts. It is found that the results obtained using the present formulation have variation within ±1.5% of the established results. After sufficient validation of the present formulation, new parametric results are given for cutout laminated composite plates resting on elastic foundations with varying elastic foundation stiffness parameters, boundary conditions, cutouts, side-to-thickness ratios, and the aspect ratio of plate and fiber angle orientations. The impact of cutouts on the dynamic behavior of laminated composite plates is investigated, and interestingly, it is observed that cutouts alter the frequency response of plates when introduced to plates without elastic foundations or plates resting on elastic foundations having low stiffness parameters; however, when cutouts are introduced to plates with high elastic foundation stiffness, the cutouts have very negligible impact on the dynamic behavior of plates. It is observed that the layout and the pattern of the cutout in the laminated composite plate affect the dynamic behavior of plates at all elastic foundation stiffnesses.

Tribo-charging and electrostatic separation of vehicle polymer particles using a new type of fluidized bed

High value-added reuse of waste vehicle polymers can effectively alleviate the global resource shortage and environmental degradation. How to separate mixed polymers cleanly and efficiently is an important prerequisite for their reuse. In the paper, polyamide (PA)/ polypropylene (PP)/acrylonitrile-butadiene-styrene (ABS) and polyethylene (PE)/PP/polyvinylchloride (PVC) of vehicle polymer mixed particles are taken as the research objects, and the tribo-electrostatic separation of three-component mixed particles is studied using the designed double-stage device for tribo-aero-electrostatic separation. First, the optimal installation angle of the fluidized bed reflow plate is determined to be 45° by using the coupling method of computational fluid dynamics and discrete element. Second, the gas velocity for forming a fast bed and the optimal charging time for two sets of mixed particles are identified by tribo-charging experiments. The separation voltage for the two sets of mixed particles is also determined using COMSOL software. Furthermore, based on the determined parameters, two sets of tribo-electrostatic separation experiments are carried out. Results showed that the purities of PA and ABS particles are more than 91%, the purities of the PE, PP (white), and PVC particles are more than 85%. The research provides a reference for the two-stage tribo-electrostatic separation of vehicle polymer mixed particles.

Development and analysis of a nano-triangular wave-shaped polarizer

As society becomes smarter, advanced optical sensing and imaging technologies utilizing visible and near-infrared regions have become increasingly prevalent. Wire-grid polarizers, which are available for broadband electromagnetic waves, are effective in improving the signal-to-noise ratio of such optical systems and enabling more advanced object detection and analysis. However, to be implemented in everyday products, low-cost manufacturing methods must be developed while maintaining high-performance optical functions. To meet these requirements, we conducted an analysis of the geometry of wire-grid polarizers, and designed and developed a wire-grid polarizer with a nano-triangular wave-shaped structure that can be fabricated using general-purpose manufacturing equipment. Once the mould is prepared, this polarizer can be fabricated via nanoimprinting and metal deposition with a normal angle or electroless plating processes. The polarizer fabricated through electroless Ni plating achieves a transmittance of 40%, which is approximately 1.4 times higher than that achieved in a previous study using electroless Ni plating on a rectangular structure with the same period. In addition, the polarizer fabricated through normal angle Al deposition operates over a wide range of wavelengths from visible light to near-infrared, and achieves a polarization extinction ratio of 24 dB at a wavelength of 550 nm and a high transmittance of 81%. High-performance polarizers can be obtained through normal-angle deposition using general-purpose equipment in contrast to the oblique-angle deposition method employed in the manufacture of conventional rectangular structure-based wire-grid polarizers, thereby contributing to cost reduction and improved manufacturability.

Experimental Study and Bearing Capacity Analysis of Retrofitted Built-Up Steel Angle Members under Axial Compression

Against the update of load design standards and requirement of long-term service, many latticed towers using steel angles subjected to gradual performance degradation must be retrofitted for bearing further social functions, e.g., electric power transmission and fifth-generation mobile communication. Therefore, this paper proposed a non-destructive reinforcement method for steel angles by avoiding unnecessary new construction or complex reinforcement procedure. The non-destructive reinforcement of a steel angle is composed of a steel angle, reinforcement plate, and fixture. Standardized fixtures are used to connect the reinforcement plate and steel angle to achieve steel angle reinforcement. In retrofitting tests, built-up steel angle members were loaded under axial compression, in which the failure mode and reinforcement effect of key parameters (e.g., clamp type, slenderness ratio, and clamp distance) were analyzed and compared, where a significant reinforcement effect was obtained with the capacity increment within 39~174%; the clamp types and clamp distance had a slight effect on bearing capacity; and the proposed reinforcement method was more effective for slender members. Based on the mechanical mechanism analysis and failure mode, the accuracy of the design method for calculating the bearing capacity of those built-up steel angle members was suggested and verified, in which a simplified mechanical model for the flexural-buckling mode was developed. The design method based on AISC360-16 agreed well with the test result and could be effectively used for calculating the flexural–torsional bearing capacity of those built-up steel angles. This study can provide a valuable reference for the design and application of non-destructive reinforcement of angle steel towers.

A novel technique for solving unsteady three-dimensional brownian motion of a thin film nanofluid flow over a rotating surface.

The motion of the fluid due to the swirling of a disk/sheet has many applications in engineering and industry. Investigating these types of problems is very difficult due to the non-linearity of the governing equations, especially when the governing equations are to be solved analytically. Time is also considered a challenge in problems, and times dependent problems are rare. This study aims to investigate the problem related to a transient rotating angled plate through two analytical techniques for the three-dimensional thin film nanomaterials flow. The geometry of research is a swirling sheet with a three-dimensional unsteady nanomaterial thin-film moment. The problem's governing equations of the conservation of mass, momentum, energy, and concentration are partial differential equations (PDEs). Solving PDEs, especially their analytical solution, is considered a serious challenge, but by using similar variables, they can be converted into ordinary differential equations (ODEs). The derived ODEs are still nonlinear, but it is possible to approximate them analytically with semi-analytical methods. This study transformed the governing PDEs into a set of nonlinear ODEs using appropriate similarity variables. The dimensionless parameters such as Prandtl number, Schmidt number, Brownian motion parameter, thermophoretic parameter, Nusselt, and Sherwood numbers are presented in ODEs, and the impact of these dimensionless parameters was considered in four cases. Every case that is considered in this problem was demonstrated with graphs. This study used modified AGM (Akbari-Ganji Method) and HAN (Hybrid analytical and numerical) methods to solve the ODEs, which are the novelty of the current study. The modified AGM is novel and has made the former AGM more complete. The second semi-analytical technique is the HAN method, and because it has been solved numerically in previous articles, this method has also been used. The new results were obtained using the modified AGM and HAN solutions. The validity of these two analytical solutions was proved when compared with the Runge-Kutta fourth-order (RK4) numerical solutions.

Effect of Inclined Orifice in Air Impingement Freezer on Heat Transfer Characteristics of Steel Strip Surface

In order to improve the heat transfer characteristics of the air impingement freezer, an impingement freezer experimental table was designed as the research object in this paper. Numerical simulation technology was used to simulate the impingement freezer experimental table on the basis of test verification. When the other structural parameters in the impingement freezer experimental table were constant, the effect of the inclination angle of the orifice plate (θ = 60°, 65°, 70°, 75°, 80°, 85°, and 90°) on the heat transfer characteristics of a steel strip surface was analyzed by two aspects, the average Nusselt number and the heat transfer uniformity. The results showed that with the increase in the inclination angle of the orifice plate (60° ≤ θ ≤ 90°), the average Nusselt number of the steel strip surface was increased by 19.39%, and the heat transfer uniformity index was decreased by 33.69%. When θ = 90°, the average Nusselt number on steel strip was the maximum, which was 263.68, and the heat transfer uniformity index was the minimum, which was 0.2039. Therefore, the heat transfer intensity and heat transfer uniformity in the air impingement freezer could be improved when the inclination angle of the orifice plates was 90°. This helps to improve the output of the air impingement freezer, reduce energy consumption, and improve the quality of frozen food.

Localization of Deformation in a Non‐Collisional Subduction Orogen: The Roles of Dip Geometry and Plate Strength on the Evolution of the Broken Andean Foreland, Sierras Pampeanas, Argentina

AbstractThe southern Central Andes (SCA, 27°–40°S) exhibit a complex deformation pattern that is influenced by multiple factors, including the present‐day dip angle of the subducting oceanic Nazca plate and the influence of inherited heterogeneities in the continental South American plate. This study employs a data‐driven geodynamic workflow to assess the role of various forcing factors in determining upper‐plate strain localization, both above the flat slab and the steeper segment to the south. These include the dip angle of the Nazca plate, the mechanically weak sedimentary basins, the thickness and composition of the continental crust, the strength of the subduction interface, and the plate velocities. Our modeling results predict two main deformation modes: (a) pure‐shear shortening in the broken foreland above the flat‐slab segment and eastward propagation of deformation, and (b) simple‐shear shortening restricted to the eastern margin of the Andean fold‐and‐thrust belt above the steep‐slab segment. While the convergence velocity and the frictional strength of the subduction interface primarily control the intensity of the deformation, inherited heterogeneities tend to localize deformation, and weak sediments leads to intensified surface deformation. Thicker crust and surface topography also influences strain localization by transferring stress to the eastern orogenic front. Above the flat‐slab segment deformation migrates eastward, which is facilitated by enhanced interface coupling. The transition between the steep and sub‐horizontal subduction segments is characterized by a diffuse transpressional shear zone, likely controlled by the change in dip geometry of the Nazca plate, and the presence of inherited faults and weak sedimentary basins.

Numerical analysis on hydrodynamic performance and hydrofoil optimization for amphibious vehicles

A numerical approach is established to study the hydrodynamic performance using an amphibious transport vehicle (ATV) as a research object. Numerical calculation based on the Reynolds average Navier–Stokes method is studied in terms of first layer grid height, surface meshing partition scale, and prismatic layer coefficient. Through uncertainty analysis, the correctness and convergence of the numerical approach are verified. Towing tests are conducted to compare the experimental data with the simulation results, which validated the reliability of the numerical approach under all working conditions. Results show that the numerical approach will affect the simulated results, with an average error of 3.91% for the resistance and 4.21% for the trim, meeting the requirements for analysis accuracy. Based on the proposed numerical approach, an optimization design is carried out to improve the hydrodynamic performance of the ATV. Effects of bow plate angle, stern flap angle, and stern flap install height are studied. Latin hypercube is used for sampling in optimization design, and the Kriging method is applied to establish an approximate model. The cross-validation is carried out using the leave-one-out method. Particle swarm optimization is used for parameter optimization, and the optimized configuration is verified using the numerical approach. Results indicate that the combination of bow plate and stern flap shows excellent improvement in the hydrodynamic performance of amphibious vehicles. Numerical error of the approximate model is only 0.292%, which fully verifies its accuracy and effectiveness. The optimized ATV configuration shows the best drag reduction performance of 38.81% compared to the original model.

Investigating the behavior of an innovative butterfly‐shaped damper: An experimental and numerical study

SummaryThe concentrically braced frame (CBF) suffered from low dissipating energy capacity although it pertains to a high lateral elastic stiffness and ultimate strength. To overcome the shortcoming, in this paper, an innovative damper made of two butterfly‐shaped plates installed at the end of the diagonal member of the CBF was considered experimentally and numerically. Also, the required equations were presented to design the system. In an experimental study, the damper showed stable hysteresis loops without any degradation in stiffness and strength up to a rotation of 12% (0.12 rad). This rotation capacity is 50% greater than the AISC limitation. Also, the numerical study indicated that by increasing the angle of main plates, the structural parameters are improved as ultimate strength (Fu), 47% to 90%; stiffness (K), 64% to 97%; energy absorption (E), 23% to 11%; and overstrength (Ω), 59% to 96%. By reduction of the damper's height, the parameters Fu, K, E, and Ω are increased by 47% to 76%, 23% to 64%, 49% to 93%, and 23% to 27%, respectively. Moreover, although the geometry of the damper affected the elastic stiffness, the stiffness in the nonlinear zone was independent of the geometry of the damper. Correspondingly, the slenderness limitations were suggested as 15 for height to thickness ratio and 22 for wide to thickness ratio.

Influence of cavity floor injection strategy on mixing improvement study of a splitter plate-assisted supersonic combustor

In the current research, an effort has been made to investigate the splitter plate-based scramjet combustor by inserting a cavity in the lower wall and observing how the different geometric parameters of the combustor, namely the cavity's aft wall angle, the bottom wall's divergence angle, and the splitter plate's angle of attack, affect the mixing performance of the supersonic combustor. Initially, experimental data from the published literature for a splitter plate is used to validate the implemented computational approach. Next, different aft wall angles of the cavity are compared, and the optimal value is found to be 120° The current investigation demonstrates that geometric modification significantly affects the performance of a splitter plate-assisted supersonic combustor. An increase in the cavity's aft wall angle improves the combustion efficiency. A further study is conducted on the splitter plate + cavity at various divergence angles of the bottom wall. According to our study, the separation region on the top wall increases as the divergence angle increases, resulting in a reduction in combustion performance. Finally, while simulating different angles of attack of splitter plate, it has been noticed that, for a negative angle of attack (-1°), the cavity provides a recirculation region and a sufficient shear mixing layer. This allows adequate air-fuel mixing to sustain combustion.

Acoustic characteristics of supersonic planar impinging jets

The present work aims to study the tonal and broadband noise associated with a supersonic planar jet, of Mach number 1.28 and Reynolds number 50000, impinging on a flat plate. Five different cases are considered corresponding to different plate distances and angles of impingement. The near-field noise is analyzed using Large Eddy Simulation (LES). For this, we employ a low dispersive and dissipative Finite Volume solver using AUSM for inviscid fluxes and third-order Runge–Kutta method for temporal discretization. The far-field noise is calculated using a hybrid approach in which the acoustic sources and mean flow are provided by the fluid solver while the far-field acoustic pressure is calculated by an acoustic solver. It solves Acoustic Perturbation Equations using a spectral/hp element method with a Discontinuous Galerkin projection. The present work highlights many important acoustics studies of impinging jets. Firstly, the far-field sound with the effect of non-uniform base fields is obtained which is important as the far-field acoustic pressure in most of the literature is reported either without any base fields or by the application of uniform base fields. Secondly, a correlation between the different modes of oscillations of the impinging jet and the production of impinging tones is studied using Modal Decomposition techniques. This analysis also sheds some light on the number of concurrent cycles for the different nozzle-to-plate distances. Lastly, the relation between the phase lag term and the distance between the plate and the nozzle exit is highlighted using a vortex tracking method. These observations can serve to provide a better understanding of the sound generation process.

On-demand tuning of mechanical stiffness and stability of Kresling origami harnessing its nonrigid folding characteristics

Being adaptive with respect to changing operating conditions and the environment is an imperative demand for advanced engineering structures. In this research, two Kresling origami units are stacked together to form an online and on-demand tunable dual-Kresling origami structure (D-KOS), allowing easy and significant change in the multistability profile and apparent stiffness without redesign. Specifically, by harnessing its nonrigid folding nature together with geometric characteristics, the D-KOS can be programmed to follow distinct paths of its strain energy contour as varying (rotational angle of the top plate of the D-KOS), which can be utilized to explicitly derive different mechanical properties. The D-KOS with identical Kresling origami units can exhibit various symmetric bistable behaviors with different energy barriers via adjusting . Such a structure becomes a monostable system as the tuning variable reaches a critical value. This change in the energy landscape and stability profile gives rise to a change in stiffness at its stable equilibria, which, as a result, creates a wide range of stiffness value one can achieve, including quasi-zero stiffness. Such tuning of does not require redesign of the structure and thus can achieve online and on-demand tailoring. To verify the concept, proof-of-concept prototypes are developed and utilized to validate the D-KOS’s mechanical tunability experimentally. Moreover, the different design parameters of the D-KOS can change its tunability. For example, the D-KOS with nonidentical Kresling origami units can possess even richer stability properties (being asymmetric bistable, symmetric bistable, and monostable) with various energy landscapes. In addition, one can also tailor the range of the adjustable stiffness by changing the design parameters, such as the ratio of the angle between the polygon side and the valley crease of the triangular facets, and the height of the Kresling origami unit.

An investigation into the micro-geometric tapered-shape surface design of the piston bore of a piston–cylinder interface in an axial piston motor

Abstract. In pursuit of design solutions that reduce energy loss and improve wear resistance for the piston–cylinder interface in an axial piston motor, a fluid-structure interaction numerical model and a new test rig of the friction force of the piston–cylinder pair are developed to achieve the analysis and design of the micro-geometric tapered-shape surface of a piston bore. The piston bore with the tapered-shape surface axial distribution length ratio of 49.44 % of the overall length is found to be the relatively optimized one. Furthermore, how the shaft speed, load pressure, and swash plate angle influence the performance of the two-type interface is analyzed. Numerical analysis results show that, compared with the traditional cylindrical piston bore design, the piston–cylinder interface with the optimized tapered-shape piston bore in the axial piston motor can achieve a significant reduction in leakage flow and friction force, and the experimental results are consistent with the simulation results.

Study on the parameters of detached dual splitter plates and comparison with single plate for VIV suppression

In the actual marine engineering environment, vortex-induced vibration will affect the safety of cylindrical structures. Rigid splitter plates have become one of the suitable VIV suppression solutions due to their simple structure and low maintenance costs. Therefore, on the basis of numerical simulation, this paper analyses the influence of the gap between parallel and non-parallel double splitter plates and the arrangement angle of non-parallel double splitter plates on the VIV suppression effect at a fixed flow rate. In addition, the VIV suppression effect of the single and dual splitter plates with the same parameter combination is evaluated under the condition of multi-flow velocity. It is found that the parallel dual splitter plate cannot provide good VIV suppression, especially when the gap exceeds the cylinder diameter, the suppression effect begins to deteriorate. However, on the basis of a certain gap between the plates, the dual splitter plate with arrangement angle is more effective than the single splitter plate in suppressing the transverse vibration of the cylinder. Therefore, when using dual splitter plates for VIV suppression, the parallel dual splitter plates should be avoided. When a better transverse vibration suppression effect is required, the arrangement angle can be appropriately changed.

Pullout Capacity of Single and Biwing Anchors in a Soft Clay Deposit: Model Investigation in a Centrifuge and FEM Predictions

One of the ways to install plate anchors in deep seabed is to drop the anchor system from the sea level and allow it to initially embed in the seabed under its own weight. Further dragging would cause the anchor to rotate and embed further into the seabed. There could be difficulties of getting the anchor plate horizontal or mooring line to be perpendicular to the plate where the maximum pullout capacity could be achieved. As part of the investigations, various aspects of the plate performance were examined through centrifuge testing in which the plate orientation and pullout angles were varied. It was presumed that dynamic stability of the anchor (during field installation) can be achieved by having the plate in biwing configuration. Therefore, the performance of the biwing anchors having different spacing between the plates was also examined in the centrifuge testing program and the findings were compared with predictions obtained through finite-element modeling (FEM). Both pullout directions and the plate angles considerably influenced the pullout capacity factors. The comparison between the predicted pullout capacity using FEM and measured pullout capacity for biwing anchors at shallow embedment depths was excellent. However, the FEM-predicted pullout capacity was noticeably lower than the measured ones for deep anchors. Pullout capacity of biwing anchors at shallow embedment depth increased as the spacing between the plates S increased from 0 to 0.5B. However, there appears to be a slight reduction in the performance in deep embedment anchors. This is also reflected in FEM findings.

Functional Outcome of Intra-articular Distal Radius Fractures Treated with Volar Variable Angled Locking Compression Plate at a Tertiary Care Center

Abstract Context: Distal radius fractures (DRFs) are the most prevalent fractures involving the upper extremity, accounting for nearly 18% of all fractures treated by orthopedic surgeons. Although numerous treatments have been established for the management of DRF, the “gold standard” treatment for intra-articular DRF is still debated. Aims: This study aimed to assess the functional and radiological outcome of intra-articular DRF treated with volar variable angled locking compression plate (LCP) at a tertiary care center with a follow-up of 2 years. Settings and Design: This was a retrospective observational study. Subjects and Methods: Thirty patients with intra-articular DRF who underwent volar variable angled LCP stabilization were included in the study and followed up for 2 years after surgery. Three-column classification was used to classify the included individuals. Disabilities of the Arm, Shoulder and Hand (QuickDASH), the Modified Mayo Wrist Score (MMWS), and the Visual Analog Scale (VAS) were utilized to assess the functional outcome. The follow-up radiographs were analyzed using the Batra anatomical score. Statistical Analysis Used: IBM SPSS (Version 20.0, Armonk, NY: IBM Corp, USA) was used for statistical analysis. Results: Thirty patients with a mean age of 44 years (34–59 years) were included in the study. Eighteen individuals had all three columns affected and 12 had two-columnar intra-articular DRF. At 2-year follow-up, the median QuickDASH Score was 2.3, MMWS was 85, VAS was 1, and the median Batra score was 90. Handgrip of the operated limb was comparable to the uninjured limb. Conclusions: Volar variable angled LCPs restore the articular architecture allowing for an excellent range of motion, good grip strength, and early functional mobility with minimal complications. Hence, LCPs appear to be superior to existing treatment techniques for DRF.

Evaluation of the Influence of Build Orientation on the Surface Roughness and Flexural Strength of 3D-Printed Denture Base Resin and Its Comparison with CAD-CAM Milled Denture Base Resin.

The purpose of this study was to determine the surface roughness and flexural strength of a three-dimensional (3D)-printed denture base resin printed with two different build plate orientations and to compare them with a computer-aided design-computer-aided manufacture (CAD-CAM) milled denture base resin. Sixty-six specimens (n = 22/group) were prepared by 3D printing and CAD-CAM technology. The group A and B specimens were 3D-printed bar-shaped denture base specimens printed at 120-degree and 135-degree build orientation, respectively, whereas group C specimens were milled using a CAD-CAM technology. The surface roughness was assessed using a noncontact profilometer with a 0.01 mm resolution and the flexural strength was determined using a three-point bend test. The maximum load in Newtons (N) at fracture, the flexural stress (MPa), and strain (mm/mm) was also measured. Data were analyzed by a statistical software package. One-way analysis of variance test was applied to determine whether significant differences existed among the study groups, followed by Bonferroni post-hoc test to determine which resin group significantly differed from the others in terms of flexural strength and surface roughness (p ≤ 0.05). The flexural stress (MPa) of group C was 200% of group A and 166% of group B. The flexural modulus was 192% of group A and 161% of group B. In contrast, group A had the lowest mean value among the three groups for all the parameters. No significant difference was seen between group A and group B. The mean roughness values of the CAD-CAM denture base resin specimens (group C) were the least (127356 nm) among all the three groups. The mean surface roughness of the 3D-printed denture base specimens (group A) was 1,34,234 nm and that of group B was (1,45,931 nm); however, it was statistically nonsignificant (p > 0.05) CONCLUSIONS: The CAD-CAM resin displayed superior surface and mechanical properties compared to the 3D-printed resin. The two different build plate angles did not have any significant effect on the surface roughness of the 3D-printed denture base resin.

Experimental and simulation investigations on perforation of titanium alloy plates against armor-piercing projectile at oblique impacts

Titanium alloy is an advanced lightweight armor material, widely used in armored vehicles. Experimental and simulation investigations on perforation of titanium alloy plates impacted by armor-piercing projectiles were performed in this study. The critical ricochet angle and failure morphology of 6 mm, 8 mm, 10 mm and 12 mm titanium alloy plates subjected to projectiles were obtained. Simultaneously, Numerical simulations of the oblique perforation of titanium alloy plates were then performed on the high-performance computer using the explicit finite element code LS-DYNA, and the validity of the numerical model was verified by comparing with the experimental results. Furthermore, typical process of projectile oblique penetration into titanium alloy target plate was analyzed and the influence of factors such as inclination angle and thickness on the ballistic performance of titanium alloy plates were discussed. It is found that the residual velocity of the projectiles decreases with the increase of inclination angle of target, indicating that increasing the inclination angle of the target plate can significantly reduce the perforation performance of armor-piercing projectile. In addition, the critical ricochet angle of titanium alloy plate is sensitive to its thickness, and larger thickness can reduce the critical ricochet angle of the titanium alloy plate.