Structural Strength Analysis Research Articles

Degradation Behavior of Rice Husk Fiber‐Reinforced PLA/PBAT Composites in Short‐Term Hydrothermal Environment

ABSTRACTThe rice husk fiber‐reinforced polylactic acid (PLA)/polybutylene adipate terephthalate (PBAT) composites were prepared by using an injection molding technique. An in‐depth investigation into degradation behavior within a short‐term hydrothermal environment, which encompassed a multi‐faceted analysis that included surface analysis, degradation process analysis, microstructure analysis, and structure strength analysis. Results show that performance of composites could be attributed to the weak interfacial adhesion, these interfacial defects can be seen as observed in the electron micrographs. In the presence of water molecules, it was observed that available interfacial bonds were susceptible to water during deformation. Moreover, the degradation behavior of the resultant network from the filler‐polymer composites could be monitored through available functional groups changes, which could provide an insight into the degradation pattern.

An experimental and numerical evaluation of the structural performance of bamboo-reinforced concrete beams

The global shift toward sustainable construction calls for eco-friendly alternatives to traditional materials. While steel reinforcement in concrete offers high strength and durability, it has significant environmental and economic drawbacks. Bamboo, a fast-growing and renewable material, is a low-cost, eco-friendly option, but concerns about its structural performance have hindered its widespread use. This study examines the structural performance of concrete beams reinforced with steel (SRC), bamboo (BRC), and hybrid steel-bamboo combinations (HYB-1 and HYB-2). It assesses ultimate failure load, load–deflection curves, failure modes, and crack patterns to explore their viability as sustainable alternatives. Beams measuring 150 × 150 × 750 mm were tested experimentally and simulated using ABAQUS software under three-point bending. SRC beams had the highest ultimate failure load (104.67 kN) and deflection (8.6 mm). BRC beams had the lowest failure load (17.97 kN), a decrease of 82.9% compared to SRC beams. HYB-1 and HYB-2 showed intermediate loads of 87.25 kN and 24.99 kN with a decrease of 16.6% and 76.1% respectively compared to SRC reference samples. Deflection in BRC beams was the least (3.0 mm), while HYB-1 and HYB-2 showed deflections of 7.4 mm and 5.6 mm. The average flexural strength for BRC beams was 82.8% lower than SRC beams, while HYB-1 and HYB-2 showed reductions of 16.9% and 76.1%. The energy absorption capacity of HYB-1 beams was close to SRC beams, with only a 29.1% reduction, while BRC and HYB-2 beams showed a reduction of 92.8% and 87.1% respectively compared to SRC beams. These findings suggest that hybrid configurations, particularly HYB-1, balance structural strength and sustainability Finite element analysis (FEA) closely matched experimental results, with an average difference of 7.44%, validating the accuracy of the modeling.

COMPUTATIONAL-EXPERIMENTAL METHOD FOR STRESS-STRAIN CURVE CONSTRUCTING UNDER CONDITIONS OF INHOMOGENEOUS STRESS FIELDS

In order to ensure reliability of structures, it is necessary to study equilibrium damage accumulation which initiates softening zones in solids. It is considered appropriate to use postcritical deformation models when conducting strength analysis of structures. However, obtaining complete stress-strain curves in standard tests is difficult due to the strain localization in the form of a neck. At the same time, the use of true stresses taking into account changes in a specimen cross section is incorrect due to the implementation of a complex stress state. In this regard, it is necessary to develop computational and experimental methods for constructing material stress-strain curves under conditions of inhomogeneous stress fields. In this case it seems reasonable to use data on strain fields on the body’s surface, which can be obtained, for example, using non-contact optical video systems. The paper presents the computational-experimental method for constructing a stress-strain curve under conditions of inhomogeneous stress fields. An elastoplastic model of an isotropic material is considered. The initial data of the method are two elastic constants, the yield stress value, the load diagram of a body with a stress concentrator, and the maximum values of strain intensity corresponding to various states. The developed method was tested by a numerical simulation of deforming an hourglass specimen and a plate with a stress concentrator. Stress-strain curves with and without a yield plateau are considered. The results demonstrate a high agreement between the initially specified and reconstructed stress-strain curves. A conclusion is made about the rationality of using the developed method when constructing stress-strain diagrams and necessity for its modernization to describe the postcritical deformation stage.

Application of composite flexible body modeling method in the analysis of friction hoist dynamic stress response

ABSTRACT In order to obtain the dynamic stress response of the drum and main shaft of a friction hoist under dynamic loads, a dynamic stress calculation model for the friction hoist was constructed based on the flexible multibody modelling method. This approach integrates modal flexible bodies and finite element flexible bodies to visualize the kinematic and dynamic characteristics of the friction hoist. The fatigue load spectrum of the main shaft and drum of the friction hoist was obtained, addressing the structural strength analysis and dynamic stress response calculation issues under dynamic loads. This method can be used as an alternative to traditional constant amplitude design load applications for fatigue strength assessment.

Investigation of torsional and fatigue resistance properties based on triply periodic minimal surfaces (TPMS)

Abstract Triply periodic minimal surfaces (TPMS) are algebraic surfaces found in nature, defined by implicit functions, and exhibit exceptional properties in various fields such as mechanics, computer graphics, and tissue engineering. This study focuses on four common minimal surface structures: Gyroid, Diamond, I-WP, and Schwarz P structures, and presents two methods for converting these surfaces into TPMS cells. These four surface structures are converted into TPMS cells, which are then organized into TPMS cylindrical units for finite element analysis. Through a comparison of the torsional mechanical properties of different minimal surfaces using the finite element method, the stress-strain curves of TPMS were generated. The findings suggest that the Schwarz P cylindrical structure remains within the elastic deformation stage under the same load, with a stress-load curve exhibiting a smaller slope, indicating superior torsional resistance. Additionally, a fatigue strength analysis of various minimal surface structures revealed that, under equivalent load conditions, the fatigue life of the Schwarz P cylindrical structure tends towards infinity.

Design of a Gantry Crawler Multifunctional Operation Platform for Wine Grape Cultivation

In response to prominent issues in existing wine grape cultivation, such as complex power machinery integration, inconvenient connection operations, and low efficiency of unilateral walking operations, a gantry track-mounted multifunctional operations platform for wine grapes was developed. The platform spans across grape trellises, enabling dual-sided operations in a single pass. Considering the high stability requirements for wine grape operations, the track walking device and hitch-lifting mechanism were developed. To accommodate the varying speed requirements of different operational stages, engine power and gearbox gear selection were calculated and selected. Structural strength analysis, steering performance analysis, and overall stability analysis of the machine were conducted. Field test results indicate a maximum operating speed of 3.85 km/h and a minimum turning radius of 3.95 m, meeting the needs of field operations. The maximum climbing angle is no more than 18°, and the machine experiences no lateral sliding or tipping when the maximum lateral tilt angle is below 28°. The hitch-lifting mechanism showed an average settlement of 1.58 mm when lifting to different heights, with a stability rate of 99.7%. This study demonstrates that the developed multifunctional operations platform can meet the field operation requirements of wine grape cultivation.

Analysis of the overall structural strength and optimization recommendations for ultra-large container ships based on the improved equivalent design wave method

Ultra-large container ships face challenges in structural strength under complex sea conditions. The traditional equivalent design wave method inadequately considers nonlinear wave effects, leading to inaccuracies in strength assessments. This article improves the method by incorporating nonlinear wave effects and optimizing wave spectrum parameters to better simulate structural responses. A study on a container ship, using refined wave load calculations and finite element analysis, focusing on stress distribution in critical hull areas. The findings show that the enhanced method more accurately reflects real loading conditions, confirming the ship’s structural soundness and offering optimization suggestions for improved safety and longevity.

Mechanical properties study of fiberglass reinforced flexible pipeline in marine applications

ABSTRACT A mechanical properties study of fibereglass reinforced flexible pipe (FGRFP) in marine applications is proposed based on the reinforced layer interface structure design, the anisotropic layer section mechanical performance test, and the structural strength analysis under the laying operation condition. Based on laboratory tests and referencing ASTM and DNV regulations, the technical design indexes of flexible marine pipe that meet strength requirements have been provided. Through tests, the maximum yield tension of FGRFP is 89.8kN, the ultimate curvature is 3.3 rad/m, the bending moment is 2312.2Nm, the torsion angle is 0.32 rad, and the torque is 2610.4Nm. Based on numerical simulation, static analysis can identify weak points in flexible pipelines. Especially, the feasibility of FGRFP structural section design was verified through dynamic analysis under the combined action of waves and currents. Finally, parameter sensitivity studies were conducted, including the effects of wave/flow direction, wave height, and period.

Structural strength and fatigue analyses of large-scale underwater compressed hydrogen energy storage accumulator

Underwater compressed hydrogen energy storage (UWCHES) is a potential solution for offshore energy storage. By taking advantage of the hydrostatic pressure of deep seawater, the compressed hydrogen can be isobarically stored in underwater artificial energy storage accumulators. The accumulator should withstand high pressure and large buoyancy and possess reliable anchoring to the seabed. In this study, the structural strength analysis and fatigue life of the large-scale accumulator is conducted employing the finite element method (FEM). The dimensionless stress prediction model and dimensionless fatigue life prediction model are developed through dimensional analysis and multivariate regression analysis. The performance of the accumulator with operating water depth of 100∼300 m, gas storage volume of 1081∼10128 m³, and concrete wall thickness of 0.1∼0.63 m is investigated. The results show that with an operating water depth of 100 m, gas storage capacity of 10,128 m3, and concrete wall thickness of 0.63 m, the maximum compressive stress is 1.43 MPa (yield strength is 60 MPa) and the maximum tensile stress of the accumulator is 2.55 MPa (yield strength is 6 MPa). The design fatigue life is 106 cycles which is larger than the expected service life of 104 cycles. Therefore, the accumulator structure meets the static strength and fatigue life. As the operating water depth increases with a consistent gas storage capacity, a transition in the stress state shifts from primarily tensile stress to predominantly compressive stress. The accuracy of the dimensionless stress prediction model and the dimensionless fatigue life prediction model were verified, with maximum deviations of 10.3 % and 13.7 %, respectively. Furthermore, the anchoring factor of safety of 1.12 is achieved.

Strength and stability analysis of composite inverted conical structure

Strength and stability analysis of composite inverted conical structure

The supporting structure strength analysis of indexing stamping machine for manufacturing thin-walled inverting steel tubes

Abstract Due to the occurrence of cracks in thin-walled inverting steel tubes during the inverting process leading to fractures, thereby failing to achieve the desired energy absorption effect, they were often manufactured by interstitial stamping process with the manual rotation of thin-walled tubes to reduce stress concentration points, which is not conducive to mass production. Therefore it proposes a new design scheme of the indexing stamping machine for mass production of thin-walled inverting tubes. And the tube supporting structure of the indexing stamping machine will undergo shear stress and axial stress during manufacturing operation. To ensure that the machine can operate properly, ANSYS software is employed to conduct strength and stability analysis for the supporting structure. The calculation results indicate that the main supporting structure can meet the strength requirements of the thin-walled inverting tube forming machine. These study findings provide some references for optimizing the structure design for indexing stamping machines.

Analysis of hardness, crystal structure and tensile strength by treatment with variations of welding current strength GTAW material SS 316L

This research occurred because problems arose, one of which was a leak in the tank from welding in the tank fabrication with the connecting material being Stainless Steel 316L. The welding process is very important to influence the results and function of the output product from this fabrication. There were leaks in 4 of the 8 tanks, namely at the welded joints. Variations in current strength in the welding machine are one of the factors that influence the welding results. In this study, we analyzed the welded joints with variations in current strength, including 60 A, 70 A, and 80 A. The analysis tests were tensile testing, hardness testing, and X-RD to find out what the deviation is for variations in current strength and to know the results of crystal structure and uniform current strength settings for maximum results and overcoming leakage problems.

Partial Force Calculation and Structural Strength Analysis of Null-Flux Coil for Superconducting Electrodynamic Suspension Train

Partial Force Calculation and Structural Strength Analysis of Null-Flux Coil for Superconducting Electrodynamic Suspension Train

Structural Strength Analysis and Optimization of Commercial Aircraft Nose Landing Gear under Towing Taxi-Out Conditions Using Finite Element Simulation and Modal Testing

In the field of civil aviation, the nose landing gear is a critical component that is prone to damage during taxiing. With the advent of new technologies such as towing taxi-out and hub motors, the nose landing gear faces increasingly complex operational environments, thereby imposing higher performance demands. Ensuring the structural safety of the nose landing gear is fundamental for the successful application of these technologies. However, current research on aircraft nose landing gear under these new conditions is somewhat lacking, particularly in terms of reliable analysis models for real-world scenarios. This study focuses on a typical Class C aircraft, specifically the B-727 model, for which a finite element model of the nose landing gear is developed. Modal testing of the aircraft’s nose landing gear is conducted using the impact hammer method, and the results are compared with those from the simulations. The experimental data indicate that the error range for the first seven natural frequencies is between 0.23% and 9.27%, confirming the high accuracy of the developed landing gear model. Furthermore, with towing taxi-out as the primary scenario, a dynamic model of the aircraft towing system is established, and an analysis on the structural strength and topological optimization of the nose landing gear under various conditions, including high speeds and heavy loads, is performed. The results show that the developed model can effectively support the analysis and prediction of the mechanical behavior of the nose landing gear. Under high-speed, heavy-load conditions, the nose landing gear experiences significantly increased loads, with the maximum deformation primarily occurring at the lower section of the shock strut’s outer cylinder. However, no damage occurred. Additionally, under these conditions, an optimized structural design for the landing gear was identified, which, while ensuring structural strength, achieves a 22.32% reduction in the mass of the outer cylinder, also ensuring safety in towing taxi-out conditions.

Deterioration and imperfection of the ship structural components and its effects on the structural integrity: A review

Abstract The design of ship structural safety is crucial to ensure the ship’s survivability during the operation. Extensive research has been conducted on ship structural components, including box girders, stiffened panels, and plates, beyond the ideal conditions by considering the implication of manufacturing processes, vessel usage, and aging in the form of defects like cracks, corrosion, and imperfections, both locally and globally. Previous research has also explored various methodologies, conditions, and parameters to understand the impact of damages and imperfections on ship structure and strength. However, there is a significant need to bridge the gap in prior research to advance technology and ship structural strength analysis. A comprehensive benchmark study specifically focused on improving ship structural component needs, identifying differences and gaps among existing studies as challenging. This article thoroughly reviews ship structural components, such as box girders, stiffened panels, and plates, while examining the effects of structural defects like corrosion, cracks, and imperfections on ship structural integrity. It synthesizes the influence of various defect parameters, including crack length, angle, position, corrosion severity, pit corrosion, pit diameter, and pit models, using finite element modeling and experimental investigations, particularly emphasizing ship structural components. The comparative analysis of methods and parameters presented in this review will serve as a valuable reference for future investigations and studies related to ship structural strength and design. The article’s contribution is expected to enhance the understanding of ship structural strength, contributing to the sustainability and effectiveness of vessel design in the global maritime industry.

Strength analysis of linear-elastic frame structures under pulse-periodic loads

Pulse-periodic loads on structures are one of the most dangerous for the their stress-strain state under dynamic load.Purpose: The aim of the work is to analyze the dynamic deformation of linear-elastic frame structures under pulse-periodic loads.Approach: It is found that a simple frame structure with additional concentrated masses affects the loading parameters (length, shape and pulse frequency). The analysis is given to physical characteristics of the deformed structure and its dynamic response under the pulse-periodic load.Research findings: Prerequisites are formulated for an unfavorable (from the position of VAT parameters) combination of the load and structural parameters.

ПРОГРАМНЕ ЗАБЕЗПЕЧЕННЯ ПРОЦЕСІВ ПРОЕКТУВАННЯ РЕДЕКДУРНИХ ПЕРЕДАЧ

The possibilities of 3D modeling for the implementation of the course project in the disciplines «Machine parts», «Machine parts and design basics», «Mechanics», «Applied mechanics» are considered. In this case, the SolidWorks program and its SolidWorks Simulation application, designed for automated strength analysis of the project structure, were used.

Structure Design and Strength Analysis of the Glass Reinforcement Plastic (GRP) Malay Traditional “Perahu Bedar”

The Perahu Bedar, a traditional fishing boat in the Terengganu region of Malaysia, has been historically crafted from Cengal wood. In response to challenges posed by wood scarcity and limitations in skilled craftsmen, this study pioneers the exploration of Glass Reinforced Plastic (GRP) as a novel alternative material for constructing the traditional Perahu Bedar, measuring 4.32 meters in length. Through a rigorous analysis, the research delves into the structural design intricacies and strength attributes of the GRP Perahu Bedar, marking a significant departure from conventional wood-based construction methods. The study conducts a comprehensive analysis of the structure design and strength characteristics of the GRP Perahu Bedar. The weight, buoyancy force, and load distribution along the boat are analyzed. The data shows varying weight and buoyancy forces along the stations, with positive load values indicating upward forces contributing to buoyancy and negative load values representing downward forces. This analysis provides insights into the boat’s stability and distribution of forces. The sheer force and bending moment along the Perahu Bedar are evaluated. The sheer force values gradually increase or decrease along the boat, while the bending moment is highest at the midsection and decreases towards the ends. These results indicate the distribution of forces and stress on the boat’s structure, aiding in understanding its integrity and stability. The Factor of Safety (FoS) analysis demonstrates a FoS value of 2.2368, indicating a safety margin greater than 1. This suggests that the GRP Perahu Bedar design meets safety requirements and can withstand applied 
 
 stresses without exceeding yield strength. The FoS value provides assurance of structural integrity and safety during normal operating conditions. In summary, this study underscores the groundbreaking potential of Glass Reinforced Plastic (GRP) as a viable alternative to traditional wooden Perahu Bedar due to very high cost of Cengal Wood (wood that been used to build Peahu Bedar). By meticulously analyzing critical factors such as weight, buoyancy, load, shear force, bending moment, and Factor of Safety (FoS), the research offers invaluable insights into the structural integrity and safety aspects of GRP Perahu Bedar. These revelations not only herald a new era of sustainable and cost-effective boatbuilding practices but also serve as a crucial step towards safeguarding and perpetuating the rich maritime heritage of the region.

Creep compliance of functionalized graphene-epoxy nanocomposites

Creep behavior is observed even at room temperature in polymers and polymer composites under constant stress. In the design of structural elements using these materials, the determination of creep compliance for structural strength and performance analysis is crucial in terms of reliability and usability. In this study, the creep compliance of pure epoxy and functionalized graphene-reinforced epoxy nanocomposites were experimentally investigated and compared at room temperature at constant stress levels of 50, 100, and 200 MPa representing the viscoelastic region, yielding region and viscoplastic region, respectively. To reveal the effect of temperature as well as stress level on this behavior, the creep compliance of epoxy and graphene-epoxy nanocomposites was investigated at 65°C in addition to room temperature after the pure graphene used as a reinforcement element was functionalized with Triton X-100, nanocomposite production was carried out. In 2h creep tests, it was observed that as the constant stress level increased, the creep compliance increased and the creep compliance of the nanocomposite was lower than that of the epoxy at all stress levels. The creep compliance of the epoxy was improved by 65% with the addition of functionalized graphene at room temperature and a stress level of 100 MPa. As the temperature increased, the creep compliance of both epoxy and functionalized graphene-epoxy nanocomposite increased due to molecular mobility and viscous flow. However, at high temperatures, the positive effect of functionalized graphene on the compliance of the epoxy is higher. At 65°C and a stress level of 100 MPa, the improvement rate of creep compliance is 78%. Functionalized graphene exhibited a more effective behavior on creep resistance at high temperatures. The obtained results showed that creep compliance was significantly affected by stress level and temperature.

Multi-site Garbage Collection Robot based on Machine Vision

At present, the problem of garbage disposal has become an urgent problem to be solved in the global energy technology revolution and transformation and development. The mainstream garbage removal methods are manual picking and mechanical collection, which has low cleaning efficiency and high cleaning cost. In order to realize the convenient and efficient recycling and cleaning of land and water garbage, a new propeller dynamics model is proposed. Through the structural strength analysis and gas-liquid two-phase flow simulation analysis, combined with the aerodynamic theory, the propeller impeller model was optimized and its suitable working parameters were explored. Based on the paddle impeller mechanism, combined with the visual recognition and classification system controlled by the algorithm combining YOLO and template matching, a multi-site garbage recycling robot based on machine vision was designed, which realized the intelligent and multi-step integration of garbage recycling, and provided a new research idea for improving the way of garbage cleaning.