Effect Of Geometry Research Articles

Rotordynamics of a Single-Stage Brush Seal in Isolation: The Effects of Variable Stiffness and Back Plate Geometry

Rotordynamics of a Single-Stage Brush Seal in Isolation: The Effects of Variable Stiffness and Back Plate Geometry

Experimental Evaluation of Geometric and Environmental Effects on Mechanically Fastened Non-Crimp Fabric Composites.

Corresponding to marine environmental regulations is important in shipbuilding and marine industries. The application of lightweight composite materials on ships is an effective approach to reducing the emission of greenhouse gases. The mechanical fastening method is a good candidate to assemble composites and conventional metals. The joint geometric and environmental effects are two important factors in mechanically fastened ship and marine structures. In this study, we evaluated the W/D (hole diameter to width ratio) and environmental effects on the bearing strength and failure mode of a mechanically fastened non-crimp fabric (NCF) composite material. To consider the effect of joint geometry, wherein hole diameters of 5, 6, 8, and 10 mm were machined. Further, by selecting three environmental conditions (UV, saltwater and low temperature), we evaluated environmental effects on bearing strength and failure modes of NCF composite specimens. The bearing strength increased as W/D decreased, and the bearing strength of the specimen exposed to low temperature and UV environments increased, while that of the specimen exposed to saltwater remained the same. From the failure mode analysis, the specimen that was exposed to salt fog showed the same failure mode as the unaged specimen. It was observed that the changes in the transition section and new failure mode in the xenon arc and low-temperature specimens.

Stability analysis of electrorheological (ER) lubricant operated multilobe hydrodynamic journal bearing

Purpose An electrorheological (ER) fluid consists of dielectric particles blended in a nonconducting oil. ER lubricants are often considered smart lubricants. This paper aims to examine the steady state and dynamic response of multilobe journal bearings using an ER lubricant. Design/methodology/approach Reynold’s equation has been used to describe the lubricant flow in the journal-bearing clearance space. The Bingham model is used to characterize the nonlinear behavior of the lubricant. The solution of the Reynolds equation is obtained using the Newton–Raphson method, with gaseous cavitation in the fluid film numerically addressed by applying a mass-conserving algorithm. The effects of lobe geometry and the applied electric field are investigated on film pressure profile, fluid film thickness, direct stiffness and damping parameters. The equation of motion for journal center coordinates is solved using the fourth-order Runge–Kutta method, to predict journal center motion trajectories. Findings Using ER lubricant combined with two-lobe journal bearing significantly improved the minimum film thickness by 49.75%, the direct stiffness parameter by 132.18% and the damping parameter by 206.3%. However, the multilobe configuration was found to negatively impact the frictional powerloss of the bearing system. In the case of multilobe configurations of journal bearings using ER lubricant, linear motion journal trajectories are observed to be reduced and exhibit increased stability. Originality/value This study presents the effect of an ER lubricant and multilobe configuration on the rotor-dynamic performance and stability analysis of hydrodynamic journal bearings. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-06-2024-0201/

A Study on Enhancing Axial Flux Motor Efficiency Using Cladding Core Technology

With the rise of eco-friendly policies, advanced motor technologies are being developed to replace fossil fuel-based engines in the mobility industry. Axial flux motors, known for their ability to reduce size and increase output torque compared to radial flux motors, require different materials and manufacturing techniques. Specifically, the production of complex stator cores and segmented magnets presents significant challenges, often leading to higher costs. To address this issue, soft magnetic composite (SMC) materials, which offer greater design flexibility, are being explored for use in stator cores. However, soft magnetic composite materials exhibit lower permeability and saturation flux density compared to laminated silicon steel, resulting in reduced output torque and efficiency. This paper investigates the effects of stator geometry on axial flux motor performance and explores cladding core technology, which combines soft magnetic composite materials with silicon steel. By conducting finite element method (FEM) analysis to evaluate the output torque and efficiency based on the shape of the silicon steel within the cladding core, this study proposes an optimized cladding core design to enhance the efficiency and output torque of axial flux motors.

Stress heterogeneity in the eastern Tibetan Plateau and implications for the present-day plateau expansion

The eastward expansion of the Tibetan Plateau has resulted in different earthquake types in the eastern Tibetan Plateau, but the mechanism remains unclear. Here, we construct a three-dimensional visco-elastoplastic finite element model considering the topography to investigate the influence of fault geometry and rheological heterogeneity on stress fields. In our best-fitting model, the minimum principal stress is nearly vertical around the southern Huya fault zone, which is adjacent to the Longmen Shan fault zone, due to the significant mid-lower crust lateral rheological heterogeneity, and the thrust stress regime accounts for the reverse fault and thrust-dominated earthquakes. In this scenario, the eastward horizontal motion of the mid-lower crust is obstructed and facilitates thrust faulting, suggesting the limited eastward expansion of the Tibetan Plateau. In contrast, the northern Huya fault zone, one of the terminal branches of the East Kunlun fault, accommodates the continuous eastward extrusion of the East Kunlun fault, where the stress regime under a more homogenized crust favors the strike-slip faulting process, along with the dominant strike-slip earthquakes. Moreover, the best-fitting of stress regime explains the thrust-dominated 2008 Ms. 8.0 Wenchuan and 2013 Ms. 7.0 Lushan earthquakes on the Longmen Shan fault zone. Combining geophysical and geodetic observations and model analyses, we propose that the hybrid deformation mode in the eastern Tibetan Plateau is accommodated by upper crustal shear and thrusting deformation and mid-lower crustal thickening driven by the gravitational potential energy gradient. Our results elucidate the mechanism for differences in strong historical earthquakes and, more importantly, isolate the effect of fault geometry from those of heterogeneous viscosity on crustal deformation and stress heterogeneity in the eastern Tibetan Plateau.

Effect of eutectic microstructure on load transfer and creep resistance in Al-Ce alloys

This study investigates the compressive creep response of hypo- and near-eutectic Al-Ce alloys via finite-element modeling (FEM), by considering the composite response of a weak, fast-creeping Al matrix containing slow-creeping Al11Ce3 eutectic reinforcement. In the as-cast microstructure of an eutectic Al-12.5 wt%Ce alloy, the Al11Ce3 eutectic phase is lamellar, regardless of the various cross-sectional geometries (Chinese-script, fish-bone, and comb-like). FEM models based on these various lamellar microstructures investigate the effect of Al11Ce3 reinforcement volume fraction, orientation, and geometry on load transfer performance between matrix and reinforcement during creep deformation. FEM predicts that, when the lamellar Al11Ce3 phase is continuous along the loading direction (where load transfer is most effective), the creep resistance of the alloy is barely affected by cross-sectional geometry of the Al11Ce3 reinforcement or by the solid-solution strengthening of the Al matrix, at constant Al11Ce3 volume fraction. However, alloy creep resistance and load transfer between phases are significantly reduced when applying load parallel to aligned, discontinuous lamellae, and they can be improved by matrix solid-solution strengthening. Furthermore, Al11Ce3 short plates (as created in Al-12.5Ce by coarsening of lamellae upon over-aging at 590 °C/24 h) provide the least creep resistance and load transfer. Lastly, multi-colony FEM models are created by combining colonies with various lamellar orientations to approximate the creep performance of polycrystalline hypo- and near-eutectic alloys which, when compared to experimental data for hypoeutectic Al-7Ce and for near-eutectic Al-(10–13)Ce, provide better predictions than single-colony FEM models or analytical solutions.

Ride Test on Vehicles Travelling Over Speed Bumps: Simulation with CarSim Software

This study explores the effects of different speed bump geometries—flat-topped, sinusoidal, and parabolic—on vehicle dynamics and ride comfort using CarSim simulations. The analysis focuses on key parameters such as vertical forces on the suspension, vertical acceleration, and the wheel surface adhesion index. The results show that flat-topped bumps generate the highest vertical forces, reaching peaks of up to 6,000 N on the front suspension, leading to increased discomfort. Sinusoidal bumps, in contrast, generate smoother transitions, with vertical forces peaking at approximately 3,500 N, improving ride comfort. At vehicle speeds of 30 km/h, the vertical forces on the suspension increase significantly, with flat-topped bumps reducing the wheel surface adhesion index to as low as 0.6, indicating a higher risk of wheel slip and compromised vehicle stability. In contrast, sinusoidal bumps maintain a more favorable adhesion index of 0.85 at similar speeds. These reductions in adhesion elevate the risk of loss of control, especially at higher speeds. The findings suggest that adaptive suspension systems, capable of adjusting damping and stiffness based on the bump geometry and vehicle speed, would enhance ride quality and stability. Additionally, smoother bump designs, such as sinusoidal profiles, are recommended to reduce the impact on vehicle dynamics, particularly in urban environments. These insights contribute to improving both vehicle design and road safety, ensuring safer and more comfortable driving experiences.

Effect of Nozzle Geometry on the Injection Characteristics of Liquid CO2 as a Volatile Lubricant and Coolant for Aluminum Hot Stamping

Effect of Nozzle Geometry on the Injection Characteristics of Liquid CO2 as a Volatile Lubricant and Coolant for Aluminum Hot Stamping

Validation of finite-element-simulated orthodontic forces produced by thermoplastic aligners: Effect of aligner geometry and creep

PurposeFinite element (FE) models for determining the orthodontic forces delivered by clear aligners often lack validation. The aim of this study was to develop and validate accurate FE models for clear aligners, considering the small but important geometrical variations from the thermoforming process and the creep behavior of the aligner material. Methods and materialsThe tooth misalignment considered was a 2.4° torque aberration (rotation about the mesial-distal axis at the level of the center of resistance) of the maxillary left central incisor. FE models were created from Micro-CT scans of a model dental arch and five nominally identical aligners with the aforementioned misfit. Fitting of the aligners onto the dental arch was simulated using Abaqus's Interference Fit function, followed by surface-to-surface frictional interaction. Stress relaxation of the aligner material was measured using double-cantilever beam bending and modeled with a Prony series. The assembled FE models were validated by comparing the predicted forces and moments delivered to the maxillary left central incisor with experimental data, obtained with a custom-built but fully calibrated apparatus. ResultsGood agreement between prediction and measurement was obtained for both the short- and long-term forces and moments. In the short-term, i.e., after 30 s, the dominant force in the labial-lingual direction had a maximum difference of 2.9% between experiment and simulation, and the dominant moment about the mesial-distal axis had a maximum difference of 8.3%. In the long-term, i.e., after 4 h, the experimental and numerical forces had a maximum difference of 8.4%. There were statistically significant differences in the forces delivered among the nominally identical aligners, which were predicted by the geometrically accurate FE models and attributed to the variations in the points of contact between the aligners and the dental arch. The decay in force applied was affected by both the viscoelastic material behavior and friction between the aligner and arch. ConclusionFor accurate prediction of the forces and moments delivered by thermoplastic aligners, FE models that can accurately capture the point contacts between the aligners and the underlying teeth are essential. Stress relaxation of the aligners could be adequately modeled using the Prony series to represent the temporal changes of their elastic modulus.

Experimental and numerical study on mounting force and withdrawal strength of self-threaded dowels in particleboard

Traditional and alternative joining techniques have been used for many years at the connection points of structural bearing systems. Especially, glued doweled and screwed type mechanical connections are widely used in wooden structures and furniture constructions. Although there are many studies related to the strength of dowel and screw joints, limited papers describe the practical use of self-threaded dowels (STDs) in the joints. In this study, thread geometry effect of the STDs in particleboard (PB) was investigated by determining the mounting force and withdrawal strength values. For this purpose, STDs including three different thread width (0,2 - 0,3 - 0,4 mm) and two different thread length (1 - 2 mm) were designed, produced and tested under static compressive and tensile forces. All STDs were produced with polylactic acid (PLA) by using Layer Plastic Deposition (LPD) method in 3D printing technology. Uniaxial compression tests were performed in order to determine the minimum mounting force while the tension tests were performed for determining the maximum withdrawal force required to put the STDs into the hole and pull out them, respectively. Numerical analysis (FEM) were used to analyze the contact pressures and stresses of the STD joints. Abaqus v6.13-1 software was utilized for the numerical analyses. In addition, multiple regression analysis was carried out to predict the mounting force and withdrawal strength of the STDs. Results showed that the predictive expressions developed provided reasonable estimates for mounting force and withdrawal strength of STDs. According to the statistical analyses; thread width, thread length and their interaction have significantly affected both mounting force and withdrawal strength of STDs. At the end of the experimental and numerical tests, STDs with 0,2 mm width and 2 mm length threads gave the lowest mounting force values, stresses and contact forces. However, the highest withdrawal strength values were obtained from the STDs with 0,3 mm width and 1 mm length threads. According to the results of the study, the optimum STD was the one with 0,3 mm thread width and 2 mm thread length. In conclusion, the STDs can be utilized as an alternative fastener to the conventional glued dowel type joints in PB. However, corner joints constructed of different kinds of wood-based composites and connected with the STDs should be investigated in the future studies.

Study of hydrogen embrittlement in steels using modified pressurized disks

The integration of hydrogen into natural gas pipelines presents challenges due to Hydrogen Embrittlement (HE), requiring critical material selection and testing methods. One such test is the Disk Pressure Test (DPT), which consists in pressurizing a clamped disk to failure. However, failure happens often at the clamping zone, making analysis difficult. This study aims to develop new disk geometries to control failure location while maintaining the test setup. Using two steel grades (a vintage X52 pipeline steel and a modern E355 modified steel with potential for pipeline use), new disk geometries were tested under helium and hydrogen at various pressure rise rates. Results show successful displacement of failure away from the clamping zones, demonstrating the effectiveness of the new geometries. Hydrogen embrittlement is demonstrated by comparing failure pressures under helium and hydrogen at various pressure rise rates. Using both material testing and simulation, this study provides insights into hydrogen embrittlement.

A probabilistic model to predict specimen geometry effects on fracture toughness in ferritic–pearlitic steels

This work describes a probabilistic framework for cleavage fracture of ferritic–pearlitic steels incorporating experimental measurements of microcrack distribution associated with the cracking of the pearlitic microstructure. A central objective of this study is to explore and further extend application of a probabilistic framework incorporating the statistics of microcracks to predict specimen geometry effects on the fracture toughness distribution for a typical ferritic–pearlitic structural steel. Fracture toughness values for an ASTM A572 Grade 50 structural steel derived from fracture tests using conventional SE(B) specimens with varying thickness and a/W-ratios provide the cleavage fracture resistance data needed to assess specimen geometry effects on the probability distribution of Jc-values. The present exploratory study successfully predicts the measured statistical distribution of cleavage fracture toughness in shallow crack specimens and provides further support of the proposed probabilistic model as a more advanced and effective engineering-level procedure in fracture assessment methodologies.

Effect of geometry on the natural frequency and seismic response characteristics of slopes subjected to pulse-like ground motions

Near-fault regions are particularly vulnerable to seismic-induced landslides due to the intense energy pulses in near-fault ground motions (NFGMs). These pulses, shaped by terrain geometry and material properties, significantly influence seismic response and slope stability. This study investigates the impact of slope geometry on natural frequency and seismic response characteristics under both pulse-like ground motions (PLGMs) and non-pulse ground motions (non-PGMs). The results show that increasing slope height lowers natural frequency, making the slope more susceptible to resonance with seismic waves, thus amplifying ground motion and increasing instability. Similarly, steeper slopes also reduces the natural frequency, heightening instability by up to 0.17%. PLGMs generate seismic responses approximately 7% stronger than those induced by non-PLGMs. Furthermore, as the frequency of PLGMs rises, so does their destructive potential. Material analysis reveals that Rock Class A has a natural frequency 68% higher than Rock Class D, making it significantly resistant to seismic deformation. These insights are essential for designing more resilient slopes in seismic-prone regions.

In Vitro Proliferation of MG-63 Cells in Additively Manufactured Ti-6Al-4V Biomimetic Lattice Structures with Varying Strut Geometry and Porosity.

Lattice structures have demonstrated the ability to provide secondary stability in orthopedic implants by promoting internal bone growth. In response to the growing prevalence of lattices in orthopedic design, we investigated the effects of porosity and unit cell geometry in additively manufactured Ti-6Al-4V biomimetic lattice structures on the osteogenesis of human MG-63 osteoblastic cell lines in vitro. We analyzed glucose consumption, alkaline phosphatase (ALP) concentration, and end-of-culture cell count as markers for osteogenic growth. Two different strut geometries were utilized (cubic and body-centered cubic), along with four different pore sizes (400, 500, 600, and 900 µm, representing 40-90% porosity in a 10 mm cube), in addition to a solid specimen. Structural characterization was performed using scanning electron microscopy. The results indicated that lattices with a 900 µm pore size exhibited the highest glucose consumption, the greatest change in ALP activity, and the highest cell count when compared to other pore sizes. Cubic 900 µm lattice structures outperformed other specimens in facilitating the maturation of viable MG-63 cells from the formation to the mineralization phase of bone remodeling, offering the most promise for osseointegration in additively manufactured titanium implants in the future. However, irrespective of a particular pore size or unit cell geometry, it was found that all the lattices were capable of promoting osteogenic growth due to surface roughness in the printed parts.

Effect of geometry and adhesion on the performance of fiber reinforced thermoplastic composite joints with metal inserts

Joints for laminated composite structures using mechanical fasteners or adhesives often face issues such as reduced strength from fiber breakage in mechanically fastened joints and complex preparation for adhesive joints. Additionally, adhesive joints require compatibility between the adhesive and the composite matrix, limiting their suitability for many thermoplastics. To address these challenges, this study explores a technique that uses metal inserts embedded during the consolidation of laminated thermoplastic composites. It investigates how the geometry of metal inserts and their adhesion to the fiber-reinforced thermoplastic composite affect the joint’s performance under out-of-plane loads. Results indicate that while mechanical locking assists in load transfer, the adhesion between the metal insert and the composite is crucial for the joint’s failure mechanism and overall performance. Strong adhesion delays final failure by requiring fiber breakage through the composite’s entire thickness, while weak adhesion leads to failure through fiber breakage on the bearing side.

Study on the groove geometry of pad in water dissolution polishing of soft brittle materials based on trajectory analysis

During the water dissolution polishing process of soft brittle materials, the pad's groove geometry plays a significant role in determining the performance. This not only affects the flow of the slurry but also directly impacts the overall distribution of the water core on the pad surface, thereby influencing the polishing effect. A trajectory model of the water core on the workpiece surface was established through kinematic analysis and the characteristics and effects of the pad's groove geometry in circular, radial, composite, and grid were studied combined with the trajectory analysis. The coefficient of variation and power spectral density were established to evaluate the trajectory uniformity. The trajectory density distribution was quantitatively analyzed to obtain a better understanding of the material removal uniformity. The simulation and experiment results indicated that the existence of groove geometry will greatly affect the flow of slurry and the surface quality. The grid groove had a better distribution of water core, which means better material removal. There exists a tradeoff between the number of grooves and their spacing. These insights offer a fresh perspective and serve as a valuable reference for further research and analysis into the groove characteristics of pads.

Geometric optimization of Kenics-type static mixers: numerical analysis of thermal and dynamic performance

Static mixers play an important role in industry by facilitating mixing and heat transfer processes. This study investigates the effect of geometry on the thermal and dynamic performance of a Kenics-type static mixer by examining four different configurations. Numerical simulations using Fluent.20 software were used to analyze parameters such as Reynolds number (ranging from 0.1 to 80), pressure drop, shear rate, fluid temperature, and Nusselt number. The results highlight the critical importance of geometry in fluid dynamics, which affects thermal performance. Among the configurations studied, the third case, characterized by three cavities occupying the entire length of the helix, proved to be the most efficient. This research thus provides valuable insights into the dynamic and thermal characteristics of kinetic static mixers, underscoring the critical importance of geometry in optimizing overall performance. What's more, this performance improvement can be observed at different Reynolds numbers, resulting in improved mixing efficiency and reduced pressure losses. This study shows that the third geometric configuration outperforms the other proposed mixers, with a performance improvement of 99%.

Numerical Investigation of the Effects of Impactor Geometry on Impact Behavior of Sandwich Structures

The aim of this study is to examine the impact performance and damage behavior of sandwich composite structures with a core material of aluminum and a facesheet of glass fiber composites using the finite element method. In the study, the effects of impactor shape, impact velocity and number of core layers on peak force, absorbed energy efficiency, maximum displacement and damage deformation were examined. For low velocity impact simulation, progressive damage analysis was performed based on the Hashin damage criterion using the MAT 54 material model in the LS DYNA finite element program. While providing the connection between the core structure and its surfaces, a Cohesive Zone Model (CZM) based on the bilinear traction-separation law was created and examined. At the end of the study, it was determined that the shape of the impactor had a significant effect on impact resistance. Energy absorption efficiency may vary as impact energy changes. However, as the impact energy increases, the energy absorption efficiency increases. It was determined that the largest and dominant damage type for all three impactors was matrix damage.

Geometry of milk liners affects milking performance in dairy cows.

The geometry of milk liners may affect milking performance and cow comfort as the milk liner is the only part of the milking machine that comes into contact with the teat. To determine the effect of alternative shape of milk liners we compared square (SQR) vs. the conventional round (RND) teat cup liner on milking performance and comfort of dairy cows. Treatment milk liners were randomly allocated to clusters within each side of the 12 a side double up-herringbone dairy shed in a complete randomised block design over two periods. Milking performance data from a total of 10 065 (late stage of lactation and once-a-day milking frequency, LATE) and 18 048 (early stage of lactation and twice-a-day milking frequency, EARLY) milking events were automatically recorded by a DeLaval milk meter, and separately analysed for LATE and EARLY, respectively. In EARLY, cow comfort behaviour was also recorded during afternoon milking sessions. Across the two study periods, average milk flow rate, milk flow rate during 0-15, 15-30 and 30-60 s after cluster attachment, and milk flow rate at cluster take-off were higher in SQR compared to RND treatment. Proportion of time in a milking session with low milk flow rate and duration of milking session were less in SQR compared to RND treatment. However, effect of geometry of milk liner on peak milk flow rate was inconsistent across the two-study periods. Peak milk flow rate was higher (P < 0.001) in SQR than RND in LATE, but higher (P < 0.001) in RND than SQR in EARLY. Stomping and kicking behaviours of cows were similar between treatments. Results of this study suggest that square milk liners potentially improve milking performance, without adverse effect on cow comfort compared to conventional round liners. Long-term, multi-site studies are required to confirm potential teat-end health benefits associated with square milk liners and further verify these results.

Compressive Strength Analysis of Additively Manufactured Zirconia Honeycomb Sandwich Ceramic Parts with Different Cellular Structures

In this study, ZrO2 honeycomb sandwich structures with different cellular geometry were manufactured by SLA 3D-printing technology to analyze the compressive strength behaviour. After the printing procedure, the samples were sintered at 1450 °C for 2h. Among the samples with different cellular geometry, ZrO2 parts with circular cells were superior to that of square and triangular honeycomb structures and 1867±320 MPa compressive strength was obtained for this structure. The stress distributions in honeycomb structures were investigated using the COMSOL Multiphysics® for exposing the effect of cellular geometry on compressive strength. While more uniform stress distributions were seen on the inner wall of the circular honeycomb sample, the cellular structure of the square and triangle honeycomb samples mostly displayed compressive stress concentration on the joints of the honeycomb structure. Also, according to Rankine failure criterion, the parts with square cellular geometries were found to be more prone to failure. The highest specific compressive strength was obtained for the ZrO2 parts with circular cellular geometry. These findings demonstrated that the ZrO2 honeycomb sandwich structures with circular cellular geometry produced using SLA ceramic 3D-printing technology may be a suitable material to utilize in lightweight structural designs.