Finite Element Analysis Simulation Research Articles

Machine-learning based process monitoring for automated composites manufacturing

AbstractAutomated fibre placement (AFP) is an advanced robotic manufacturing technique which can overcome the challenges of traditional composite manufacturing. The interlaminar strength of AFP-manufactured composites depends on the in-situ thermal history during manufacturing. The thermal history is controlled by the choice of processing conditions and improper interfacial temperatures may result in insufficient bonding. Being able to better predict such maintenance issues in real-time is an important focus of smart manufacturing and Industry 4.0 to improve manufacturing operations. The data analysis of real-time temperature measurements during AFP composites manufacturing requires the temperature profiles from Finite Element Analysis (FEA) based simulations of the AFP process to better predict the quality of layup. However, the FEA simulations of the AFP process are computationally expensive. This study focuses on developing a digital tool enabling real-time process monitoring and predictive maintenance of the AFP process. The digital tool constitutes a machine learning-based surrogate model based on results from Finite Element Analysis (FEA) simulations of the AFP process to predict the in-situ thermal profile during AFP manufacturing. Multivariate Linear Regression, Multivariate Polynomial Regression, Support Vector Machine, Random Forest and Artificial Neural Network (ANN)-based models are compared to conclude that ANN based surrogate model performs best by predicting the important parameters of thermal profiles with a mean absolute percentage error of 1.56% on additional test data and reducing the time by four orders of magnitude as compared to FEA simulations. The predicted thermal profile can be compared with the real-time in-situ temperatures during manufacturing to predict the quality of the layup. A GUI application is developed to provide predicted thermal profiles data for analysis in conjunction with real-time temperatures during manufacturing enabling monitoring and predictive maintenance of the AFP process and paving way for the development of a digital twin of the AFP composites manufacturing process.

Test and application of movable steel barrier with grade SB light composite corrugated beam

In this study, movable steel barrier with grade SB light composite corrugated beam is designed, which addresses the problems of the prior central partition belt portable guardrail in terms of easy mobility, local safety, easy construction, and other indications. This guardrail employs explicit algorithms to conduct a dynamic finite element simulation analysis and a real vehicle crash test, and verifies the guardrails' blocking, guiding, and buffering functions in accordance with the SB level collision conditions listed in the Standard for Safety Performance Evaluation of Highway Barriers (JTG B05-01-2013). According to the results, the safety performance of SB grade lightweight composite corrugated beam movable steel guardrail meets the requirements of the Standard for Safety Performance Evaluation of Highway Barriers (JTG B05-01-2013). In addition, the guardrail can be opened for 12 meters in 1 minute and returned to close in 2 minutes. The opening and restoration of the movable guardrail is superior to the previous central divider movable guardrail. This guardrail has been tried for some high-speed and its safety performance has been verified again in actual high-speed vehicle collisions.

Bearing capacity of bolted longitudinal seams of corrugated steel structures under compression

This study investigates the bearing performance of the longitudinal seams of corrugated steel plate structures with high-strength bolted connections. Axial compression testing and finite element simulation analysis were performed, considering factors such as the strengths of the corrugated steel plates and the grade and number of bolts. We found that the torque coefficient and standard deviation of hot-dip galvanised high-strength bolts were higher than the specification requirements and that the bolts had to be reasonably screwed according to the measured torque coefficient to ensure seam reliability. Seams with plate bearing failure could entirely utilise the strength of the corrugated steel plate and exhibit better ductility than those with bolt shear failure. Under the bolt shear failure mode, increasing the strength of the steel plate reduced the ultimate bearing capacity of the seam. Therefore, the strength of the corrugated steel plate and specifications of the bolts had to match to leverage the synergy between them. In the bolt shear failure mode, an increase in the number of high-strength bolts in the seam could proportionally increase the slip platform load and ultimate bearing capacity of the specimen. Owing to the geometry, the ultimate strain and deformation of the plate at the crest of the corrugation were considerably greater than those at the trough. Equations for calculating the bearing capacities of high-strength bolted connections of corrugated steel plates were established, enabling accurate predictions of the seam failure mode and strength. The obtained strengths were approximately 98% of the measured seam strength.

Effect of the welding procedure on the deformation of superposed welds of a low carbon steel

This study compared gas-metal arc welding (GMAW) and laser beam welding (LBW) for the superposed joining of two low-carbon steels. The motivation was to reduce the visible defects (notches) in the external part of one of the sheets. Both welding processes produced sound welds characterized by ferrite and pearlite; however, the notch disappeared when LBW was used. The hardness values of the fusion and heat-affected zones were similar for both processes, but the tensile strengths were very different. The shear tensile strengths of the LBW and GMAW were 415 and 84 MPa, respectively. Finite element analysis simulations indicated a more diffuse distribution of the von Mises stress throughout the welded component. The GMAW FEA model also presented a defect because of excessive heat transfer and residual stresses. In conclusion, LBW can replace GMAW in this particular case with improvements in appearance, productivity, and mechanical strength.

Multiscale characterization and design of cellulose composites based on polymers with movable cross-links

To combine the conflicting properties of impact resistance, stiffness, and toughness, we focused on composite materials reinforced with cellulose nanofibers and polymers with movable cross-links using cyclic macromonomers and analyzed their mechanical properties through experiments and computational simulations. Based on the experimental foundation, the mechanical properties of cellulose nanofibers modified with citric acid and flexible crosslinked polymer composites using cyclodextrin were investigated. On the other hand, multi-scale finite element analysis simulation based on homogenization theory was employed to systematically clarify the effects of aspect ratio and content ratio of cellulose fibers by considering polymer blending and modification of molecular structure in the base material. For modification of the matrix polymers and the fiber morphologies, the elastic modulus of the cellulose composite was comprehensively organized by the fiber contribution based on strain energy. A design method for cellulose composites based on fiber contribution proportion was also developed. The design method was applied to a new cellulose composite with a different polymer of the matrix, and it was demonstrated that the elastic modulus can be predicted with an error of less than 10 %.

Deep learning-based vibration stress and fatigue-life prediction of a battery-pack system

The primary concerns of the automotive industry are structural integrity and battery-pack system (BPS) reliability. To ascertain the appropriate thickness of critical BPS components (e.g., the long bracket, crossbeam, and bottom shell), engineers are required to perform several simulations of finite element (FE) analysis. This procedure is laborious and requires a significant amount of time. This study introduces a very effective approach for predicting vibration-induced stress and fatigue life, intending to enhance dependability in the design process. Firstly, a three-layer lithium battery model is utilized to investigate the impact of vibration on the maximal Mises stress at various states of charge. This information is used to model the BPS, including the batteries. The nonlinear FE model of the BPS is validated using the modal test results. Secondly, a sensitivity analysis is performed to ascertain the impact of component thickness on the maximum Mises stress. For vibration simulations, multiple design variables are selected to collect data. Next, the nonlinear relationship between inputs (thicknesses of critical components) and outputs (maximum Mises stress and minimum fatigue life) is described using a deep learning (DL) modeling framework with forward and backward propagation. Finally, the accuracy of the DL model is assessed by measuring error functions and comparing its performance to six commonly employed methods. Furthermore, the inclusion of Gaussian noise is employed to assess the model’s robustness and ability to generalize. Additionally, the establishment of fatigue-life and stress boundaries serves to offer designers valuable insights. The results indicate that the proposed method for predicting vibration stress and fatigue life is highly efficient and cost-effective, making it useful for the design of a robust and reliable BPS.

Modified Induction Machine Equivalent Circuit Including Solid Shaft Eddy Currents

The shaft eddy currents cause a significant saturation in two-pole induction machines (IMs) as they generate an opposing field and repulse the main flux, thus tightening the flux path. This results in inaccurate performance estimations with the magnetizing inductance measured in no-load conditions when the machine is loaded. This article presents a modified IM equivalent circuit considering the rotor back iron saturation effects caused by the solid shaft eddy currents using experimental measurements and recursive parameter estimation techniques. The classical equivalent circuit (CEC) parameters are determined with the standard test techniques followed by the parameter estimation of the newly introduced modified equivalent circuit (MEC) parameters. The proposed modified equivalent circuit is benchmarked with CEC and finite element analysis (FEA) simulations with and without considering eddy effects. The proposed MEC model and the FEA that consider eddy effects performed better than the other models and yielded a negligibly small error over a wide range of loading conditions. Compared to the FEA, the proposed MEC estimates the IM performance much faster, which makes it more appealing for IM performance estimations.

Effects of chamber shapes on maneuverability and control property of endoscope-support soft actuators.

Introduction: Minimally Invasive Surgery (MIS) offers targeted surgical access with reduced invasiveness; however, the maneuverability challenges of traditional instruments in this domain underscore the need for innovative solutions. Soft actuators activated by fluids or gases present a promising strategy for augmenting endoscopic capabilities, thereby enhancing the surgical precision in MIS. This study aimed to explore the intricate dynamics of the interactions between soft actuators and endoscopes, with an emphasis on the pivotal role of cross-sectional chamber shapes. While previous studies have touched on the influence of chamber shapes on bending properties, we provide a comprehensive exploration. We explore how these shapes modulate friction forces, which in turn influence the interactions governing bending, response, and stiffness adjustability, all of which are essential for enhancing endoscope maneuverability in MIS contexts. Methods: A novel bilateral symmetrical air chamber design was adopted to investigate various chamber shapes. We employed finite element analysis (FEA) simulations followed by prototype testing to evaluate the interactions driven by these chamber shapes and to discern their impact on actuator properties. Recognizing the pivotal role of friction in these interactions, we conducted dedicated friction experiments. These experiments further deepened our understanding of the relationship between chamber shape and friction, and how this synergy influences the properties of the actuator. Results: Our findings showed that actuators with wider chambers generate larger friction forces, thereby enhancing the interaction and improving the bending, response, and stiffness adjustability. Additionally, the soft actuator significantly improved the maneuverability and bending radius of the endoscope, demonstrating enhanced navigation capabilities in complex environments. Discussion: The shape of a cross-sectional chamber plays a pivotal role in designing soft actuators for MIS applications. Our research emphasizes the importance of this design component, offering key insights for the development of endoscope-supporting soft actuators that can effectively handle intricate actuator-endoscope interactions, thereby enhancing surgical outcomes.

Design Evaluation of Air Receiver Tank for Gas Power Plant Using Finite Element Analysis

In order to improve the power capacity in Bali, an air receiver tank is required, which is a tank used to store compressed air produced by an air compressor. The design of this air receiver tank aims to analyze the performance of the existing air receiver tank and compare it with the proposed design in this research. The analysis includes the impact of various factors on the design of the air receiver tank regarding its performance. Several components were created during the fabrication process, including the shell, bottom head, top head, and several instruments of the required components with design pressures of 10, 12, and 1.6 MPa. The research process is mapped using three methods: manual calculations based on ASME Section VIII Division I standards, finite element analysis simulation using the SolidWorks application, and hydrostatic testing. The manual calculation results indicate a shell thickness of 7.57868 mm and head top and bottom thicknesses of 7.53 mm, which are capable of accommodating the maximum pressure with MAWP (Maximum Allowable Working Pressure) values of 1.38 MPa for both the shell and head. The design script support calculation yields a result of 0.3 mm. Based on the finite element analysis simulation using the SolidWorks application, the results show that the tank can withstand a load of up to 1.6 MPa, with material stresses at the head top being 90.0 MPa, head bottom at 0.1 MPa, and shell at 15.5 MPa, with a Min-Max value of 192.0 MPa. Hydrostatic testing with variations in time indicates that the tank can handle a pressure of up to 1.6 MPa, as shown by pressure gauge II-III and temperature gauge II and III, maintaining a stable reading of 1.6 MPa and 76°F.

Optimal Design of Thermal Cycling Reliability for Plastic Ball Grid Array Assembly Via Finite Element Method and Taguchi Method

Abstract A finite element simulation analysis model was developed for a plastic ball grid array (PBGA) assembly to analyze its behavior under thermal cyclic loading conditions. The stress distribution in the SAC305 solder joints at different locations within the array was investigated by using ANAND constitutive equations. Subsequently, the thermal fatigue life of the key solder joints was quantified. The study also examined the influence of the solder joint diameter, substrate thickness, solder joint height, printed circuit board (PCB) thickness, and mold compound height on solder joint stress. Optimization of assembly parameters was achieved through the application of the Taguchi method. An extensive analysis was conducted using different assembly parameter combinations, employing the L9(34) orthogonal array design to explore the thermal cycling effects. The computed average Von Mises stress Δσ for the critical thin-layer elements of solder joints located in hazardous positions within the assembly was notably affected by variations in the solder joint height, substrate thickness, solder joint diameter, and mold compound height. This impact ranked in descending order of significance as solder joint height, substrate thickness, solder joint diameter, and mold compound height. The optimal parameter combination determined was a solder joint height of 0.70 mm, a solder joint diameter of 0.85 mm, a substrate thickness of 0.51 mm, and a mold compound height of 1.12 mm. Implementing this optimized configuration led to a significant 4.07% reduction in average stress Δσ for the critical thin-layer elements within hazardous solder joints. Moreover, the extension of the thermal fatigue life was notably improved, achieving an impressive 51.72% increase.

Buckling and fracture characterization of pristine bundles of vertically aligned carbon nanotubes using quantitative in situ TEM axial compression

This work investigates the mechanical deformation and fracture characteristics of pristine bundles of vertically aligned multi-walled carbon nanotubes (MWCNTs) subjected to axial compression in situ transmission electron microscope (TEM). Accurate measurements of force-displacement data were collected simultaneously with real-time TEM videos of the deformation process. Two distinct regimes were observed in the force-displacement curve: (1) an initial elastic section with a linear slope, followed by (2) a transition to a force plateau at a critical buckling force. Morphological data revealed coordinated buckling of the pristine bundle, indicating strong van der Waals (VdW) forces between the nanotubes. The experimental setup measured an effective modulus of 83.9 GPa for an MWCNT bundle, which was in agreement with finite element analysis (FEA) simulations. FEA also highlighted the significant role of VdW forces in the bundle mechanical reactions. Furthermore, we identified nickel nanoparticles as key players in the fracture behavior of the bundles, acting as nucleation sites for defects. The direct mechanical measurements of MWCNT bundles provide valuable insights into their mechanical deformation and fracture behavior, while correlating it to the morphology of the bundle. Understanding these interactions at the bundle level is crucial for improving the reliability and durability of VACNTs-based components.

CONTINUOUSLY CONTROLLABLE ARTIFICIAL DETRUSOR SYSTEM AND ITS CONTROL STRATEGY

In this paper, a new artificial detrusor system is proposed to achieve continuous control over the urination process and realize the normal voiding process of human (NVPH). The system is powered by a wireless power transfer (WPT) module, controlled by a control module and actuated by a shape memory alloy (SMA) spring. The design method of the SMA springs is proposed. Two control strategies are proposed to achieve NVPH. The first strategy is an open-loop control strategy based on the result of finite element analysis (FEM) simulation results and calculation of the derived system governing equations. The second strategy is a closed-loop control strategy based on the collection of feedback data and algorithmic processing. Both strategies are verified by experiments. The results show that the proposed system is feasible and both strategies can achieve NVPH. It can provide reference and guidance for the design of artificial detrusor system and formulation of control strategies.

Characterization of Fe-6Si Soft Magnetic Alloy Produced by Laser-Directed Energy Deposition Additive Manufacturing

Commercial electrical steels, Fe-Si alloys with < 4 wt.% Si, are inexpensive and efficient materials for electrical power conversion. Further efficiency improvements require increasing the silicon concentration to 6 wt.%, at which point the material becomes brittle and difficult to form by conventional rolling and sheet fabrication methods. Additive manufacturing stands to overcome challenges with commercial manufacturing techniques by leveraging near-net-shape fabrication. The wide array of process conditions provides additive manufacturing with increased flexibility, enabling control over the microstructure and mechanical properties. This work explores the microstructures and magnetic properties of ring-shaped Fe-Si alloys produced using concentric and cross-hatch tool paths on a laser-directed energy deposition additive manufacturing system. Concentric-built samples exhibit elongated grain structures while cross-hatch-built samples comprise lower aspect ratio grain structures. Thermal finite element analysis simulations model the stress conditions produced by the different scan path geometries. Microhardness measurements probe the mechanical properties as a function of anneal temperature, providing a qualitative understanding of the intergranular defect density. Soft magnetic properties measured under quasistatic and AC conditions show frequency- and microstructure-dependent coercivity and permeability. Finally, analysis of the core loss quantifies how the build strategies and thermal treatments influence efficiency in electrical power conversion applications. Understanding the influences of scan path geometry and thermal treatment provides a pathway towards application of additively manufactured soft magnetic materials.

Biomechanical analysis of peri-prosthetic bone response to hybrid threaded zirconia dental implants: An in silico model

The biomechanical response of mandibular bone determines primary stability and concomitant osseointegration of dental implants. This study explores the impact of nature of loading and bone conditions on biomechanical response of hybrid threaded single-piece zirconia dental implants. To develop such understanding, three implants (SQ_V, V_BUT, and V_V), with different combinations of threads, square (SQ), buttress (BUT), and triangular (V), have been investigated. Finite Element Analysis (FEA) was carried out to simulate implantation at the molar position of mandible of varying densities under axial (≤500 N) and oblique (118.2 N) loadings. Patient-specific bone conditions (for a wider population) were considered by scaling the density and the elastic modulus of mandible to represent, ‘weak’, ‘healthy’, and ‘strong’ bone conditions. FEA results revealed that SQ_V and V_BUT implants exhibited a better biomechanical response without significant variation (<0.5%) in von Mises stress, regardless of bone density and axial loadings. These implants are predicted to perform with clinically acceptable factor of safety under investigated implantation scenarios, whereas V_BUT implant showed a larger variation (∼±12%). FEA simulation with oblique loading further validated such results. The ‘weak’ bone conditions resulted in maximum peri-implant microstrain, whereas ‘strong and healthy' bone exhibited values close to the permissible range of physiological remodeling. The maximum micromotion (∼12.3 ± 6.2 μm for ‘weak’ bone) at bone-implant interface suggested that implant loosening and impaired osseointegration will not occur in any of selected virtual implantation cases. Both SQ_V and V_BUT implants will be considered further in implant development, involving manufacturing and product prototype validation. Taken together, the critical analysis of FEA results indicates a significant impact of bone density and distinct combinations of external threads on the biomechanical responses, in both the implant and the surrounding bone.

Design of 3D-printed prostheses for reconstruction of periacetabular bone tumors using topology optimization.

Background: Prostheses for the reconstruction of periacetabular bone tumors are prone to instigate stress shielding. The purpose of this study is to design 3D-printed prostheses with topology optimization (TO) for the reconstruction of periacetabular bone tumors and to add porous structures to reduce stress shielding and facilitate integration between prostheses and host bone. Methods: Utilizing patient CT data, we constructed a finite element analysis (FEA) model. Subsequent phases encompassed carrying out TO on the designated area, utilizing the solid isotropic material penalization model (SIMP), and this optimized removal area was replaced with a porous structure. Further analyses included preoperative FEA simulations to comparatively evaluate parameters, including maximum stress, stress distribution, strain energy density (SED), and the relative micromotion of prostheses before and after TO. Furthermore, FEA based on patients' postoperative CT data was conducted again to assess the potential risk of stress shielding subsequent to implantation. Ultimately, preliminary follow-up findings from two patients were documented. Results: In both prostheses, the SED before and after TO increased by 143.61% (from 0.10322 to 0.25145mJ/mm3) and 35.050% (from 0.30964 to 0.41817mJ/mm3) respectively, showing significant differences (p < 0.001). The peak stress in the Type II prosthesis decreased by 10.494% (from 77.227 to 69.123MPa), while there was no significant change in peak stress for the Type I prosthesis. There were no significant changes in stress distribution or the proportion of regions with micromotion less than 28μm before and after TO for either prosthesis. Postoperative FEA verified results showed that the stress in the pelvis and prostheses remained at relatively low levels. The results of follow-up showed that the patients had successful osseointegration and their MSTS scores at the 12thmonth after surgery were both 100%. Conclusion: These two types of 3D-printed porous prostheses using TO for periacetabular bone tumor reconstruction offer advantages over traditional prostheses by reducing stress shielding and promoting osseointegration, while maintaining the original stiffness of the prosthesis. Furthermore, in vivo experiments show that these prostheses meet the requirements for daily activities of patients. This study provides a valuable reference for the design of future periacetabular bone tumor reconstruction prostheses.

Experimental and Numerical Investigations on the Spherical Steel Bearing Capacity of New Anti-Separation Design

To solve the issues of slippage and dislodging caused by insufficient grout compactness in railway bridge spherical steel bearings, a novel kind of anti-separation spherical steel bearing is presented. Firstly, a comparative test model was meticulously designed and constructed for the bearing-stone assembly, encompassing both the traditional spherical steel bearing and the innovative anti-separation spherical steel bearing. Next, mechanical performance testing and finite element simulation analysis were completed. Finally, an empirical equation for the vertical load-strain fitting of the bearing was established. The results demonstrate that, under the maximum vertical static load, the convex spherical crown anti-separation design of the new anti-dislodging bearing is not sensitive to the bearing performance of the bearing-bedding stone combination. All indexes also meet the specifications. Under the action of cyclic load, the error of each parameter between finite element analysis and test results is less than 7%, which shows that the new anti- separation spherical bearing has higher bearing capacity and better fatigue resistance; the fitted value of the established bearing vertical load-strain calculation formula is in agreement with the test value by more than 0.95, which can predict whether the new anti-separation bearing fails.

Design and frequency control study of small-sized magnetorheological finishing device applied in optical manufacturing

With the continuous development of various advanced optical systems, there is an increasing demand for optical components with small apertures (generally ranging from a few millimeters to tens of millimeters in diameter), steep slopes, or even specific relief structures on their surfaces (such as continuous phase elements). These optical components all require high surface quality and shape accuracy. However, existing magnetorheological finishing (MRF) devices have larger dimensions, and the obtained removal function size is relatively larger than the size of small-diameter optical components, making it difficult to achieve high surface shape accuracy after processing. To achieve high-precision machining of small-aperture optical components and obtain higher frequency control capabilities, this study first designed and optimized a small-size MRF device with a 13 mm polishing wheel. Based on theoretical and finite element simulation analyses, the magnetic pole structure of the small-size MRF device was designed. The orthogonal experimental method was used to optimize the key parameters of the magnetic pole according to the magnetic field design requirements, and the device was constructed. Its performance and stability were experimentally analyzed, and the results showed that the peak magnetic field intensity in the polishing area of the device was about 230mT, which met the polishing requirements, and both its long-term and short-term processing stabilities met the design requirements. In addition, different sizes of removal functions were analyzed for frequency control ability, and theoretical and spectral analyses of the removal function indicated that the small-size removal function had better low-frequency error correction ability, while for mid-frequency band and mid-frequency ripple error, the opposite was true. The experimental results showed that when the optical component was shaped by 20 %, the low-frequency convergence capability of the 100 mm polishing device was only 18.72 %, much lower than that of the 13 mm polishing device, which was 52.51 %.Moreover, the mid-frequency ripple spectrum amplitude for the 13 mm polishing device was more than 15 times higher than that for the 100 mm polishing device when removing 50 nm material, and the mid-frequency root mean square (RMS) increased significantly, deteriorating the surface mid-frequency error of the optical component. Therefore, when performing magnetorheological polishing on an optical component surface, a process of using large-size MRF devices for roughing combined with small-size MRF devices for finishing can ensure machining efficiency while controlling low-frequency and mid-frequency errors well. This study provides theoretical support for the magnetic pole design of MRF devices and broadens the frequency spectrum correction ability and application range of MRF processes, which has great application value.

Literature review on thin-walled and cellular structure designs for energy absorption

Bio-inspired structure is a topic of immense interest to researchers worldwide. In order to maximize energy absorption through biomimetic structures, this article presents bio-inspired structure particularly, thin walled and cellular structures thorough analysis of the interactions between experimental research and Finite Element Analysis (FEA) simulations. The study compiles the prior research on experimental investigations of thin-walled and cellular biomimetic structures in order to understand the significance of biomimetic structural energy absorption. These inventive works of nature serve as inspiration for these designs, which provide engineering solutions that excel in impact resistance and energy dissipation abilities. The study further highlights the mutual advantages of combining experimental research with FEA models, which enable a deeper understanding of the impact response and energy absorption mechanisms inherent in biomimetic structures, by exploring into recent developments in material science and design methodologies. The article emphasizes how important validations are in bringing experimental results in line with FEA predictions. Furthermore, the practical applications demonstrated in fields like aircraft engineering, automotive safety, and protections can serve as excellent examples of the paradigm-shifting potential of this method for boosting impact protection. This review proposes novel research avenues aimed at fully harnessing the potential of biomimetic architectures to enhance energy absorption, all while acknowledging and addressing the associated challenges.

Brazilian splitting experiment and finite element simulation analysis of the influence of bedding loading angle on shale fracture mode

During the diagenetic processes of compaction and cementation, shale forms multiple beddings, significantly effecting the rock anisotropy. Therefore, it is important to study the effect of bedding on the mechanical properties of shale to guide fracturing engineering. To study the failure mode and fracture morphology of shale with bedding planes under different bedding dip angles, Brazilian disc splitting tests and finite element numerical simulations are performed for shale samples and the results are compared. (1) The bedding angle has a significant effect on the failure mode and tensile strength of shale, and the tensile strength tends to increase with increasing bedding angle. (2) The failure modes of shale under different bedding dip angles can be divided into three types: tensile failure along the bedding plane; comprehensive shear and tensile failure of the matrix and the bedding plane; and matrix tensile failure. (3) The direction of secondary cracks is mostly perpendicular to the bedding plane, and a smaller angle between the load application direction and the bedding direction results in a larger number of generated cracks with more complex shapes. (4) When the loading angle of the bedding is 30°, the tensile strength is low and the matrix and the bedding plane are comprehensively destroyed by shear and tension, resulting in a more complex joint mesh; conversely, when the bedding angle is greater than 60°, the tensile strength increases and the complexity of the seam mesh decreases. These findings can provide guidance for the selection of the bedding angle and the design of fracturing schemes in fracturing engineering.

RANCANG BANGUN GENERATOR MAGNET PERMANEN FLUKSI AKSIAL SINGLE STATOR SINGLE ROTOR

Permanent magnet synchronous generator is one type of generator that is widely used for small-scale power generation, because it can be operated at low speed, so it does not require a gearbox in its operation. This paper proposes the manufacture of a low speed axial flux permanent magnet synchronous generator that can be used for small-scale electric power generation. The generator is designed in the form of a single stator single rotor. The generator stator is designed using fiberglass as the holder for the nine coils, while the rotor is designed in a disc shape using aluminum as the holder for the Neodymium N52 permanent magnet. The generator design was validated through Finite Element Analysis simulation using solidwork and tested through experiments using an induction motor as the driving force. Tests were carried out with varying air gaps and rotational speeds. The experimental results show that the generator can produce a voltage of 15.4 Volts when the generator is rotated at a speed of 500 rpm. The generator can also produce a maximum power of 400 Watts with an air gap of 2 mm