Stress Analysis Of Structures Research Articles

Topologically optimised facade brackets: an embodied carbon, structural and residual stress analysis

The research investigates the topological optimisation of the metal brackets that connect curtain wall panelling to the floor slabs of a building. As is typically the case with standard building components, the brackets are overdesigned with higher load margins than real applied loads. Optimising them results in reduced mass and a more evenly spread stress distribution. Correspondingly, the question that the project asks is whether the optimised designs have a comparable structural performance to the standard bracketry used in construction, and a lower embodied carbon. To answer this, several optimisations of a standard facade bracket are performed, resulting in a total of six converged design options, with three of them progressed for fabrication. The manufactured designs are then horizontal and vertical load and residual stress tested to assess their performance, and an embodied carbon analysis is performed to calculate the corresponding emissions for raw material extraction, processing, and component fabrication. The results indicate the presence of compressive yield magnitude residual stresses, and that structural performance is comparable to a standard bracket, but embodied carbon is in most cases higher. The paper concludes with a discussion of the findings, and possible next steps in the optimisation, structural testing, and embodied carbon analysis workflow.

Finite element stress analysis and topological optimization of a commercial aircraft seat structure

In recent years, the Finite Element Method (FEM) has emerged as a cornerstone in the field of seating design, particularly within the aircraft industry. Over the past decade, significant advancements in Finite Element (FE) analysis techniques have revolutionized the seat industry, enabling the creation of safer and more cost-effective seat designs. The accuracy of FE analysis plays a pivotal role in this transformation. In the process of constructing a reliable finite element model, the selection and precise manipulation of key parameters are paramount. These crucial parameters encompass element size, time scale, analysis type, and material model. Properly defining and implementing these parameters ensures that the FE model produces accurate results, closely mirroring real-world performance. Verification of Finite Element Analysis (FEA) results is commonly accomplished through experimental methods. Notably, when the parameters are appropriately integrated into the modelling process, FE analysis outcomes closely align with experimental results. This study aims to leverage the power of FEM in performing static stress analysis and topology optimization of aircraft seats using the SOLIDWORKS commercial finite element platform. By simulating loading conditions, this research calculates static stresses and displacements experienced by the aircraft seat. Through a comprehensive topology optimization study, the weight of the airplane seat is remarkably reduced by up to 30%, while still prioritizing passenger safety. The success of this optimization showcases the potential for substantial weight savings in aircraft seat design without compromising safety standards.

Automatic monitoring and structural stress analysis during ultra-large onshore caisson sinking construction

During the sinking process of ultra-large onshore caisson, the structural stress of caisson will change significantly due to the changes of earth pressure, end resistance, water level in caisson and attitude of caisson. Based on the south anchoring onshore caisson project of Nanjing Longtan Yangtze River Bridge, the structural stress analyses were carried out based on the automated caisson monitoring data. The results show that the automated monitoring system can acquire the key data of caisson in real time and efficiently, and the monitoring results reflect the structural stress and displacement characteristics in different construction stages. The vertical earth pressure at the bottom four corners of the caisson is significantly greater than the other positions, indicating that there is an obvious stress concentration phenomenon at the four corners. The stress at the bottom of the horizontal earth pressure monitoring is smaller than that at the middle and bottom of caisson, which verifies the existence of stress disturbance area around the cutting. Steel shell concrete at the bottom of partition wall is the weakest position of caisson structure, and the structural safety risk is higher from the first casting to the second sinking. If the risk of tensile cracking occurs in the process of casting, each diagonal can be carried out several times to make full use of the structure's own resistance to reduce the development of tensile stress. The conclusion can be used for reference in the design and construction of similar projects.

On the modelling of distorted thin-walled stiffened panels via a scale reduction approach for a simplified structural stress analysis

To reduce the weight of cruise ships, the shipbuilding industry is interested in thin-walled superstructures, where the thickness of butt-welded plates in stiffened panels is under 5 mm. Compared to thick plates, thin ones can develop severe welding-induced distortions, which limit the validity of recommended early-design structural stress assessment methods. Therefore, computationally costly 3D non-linear numerical analysis must be used. For a quick and effective early design, this paper investigates on simplified computational models for thin-walled panels under uni-axial tension, considering the distortions measured on 4-mm thick, full-scale ship-deck panels. A 2D simply-supported analytical plate is shown to be sufficiently accurate (i.e., error <10%) at 150MPa for a distortion with maximum slope within 0.02rad and amplitude smaller than the thickness (t). Moreover, a 1D beam numerical analysis efficiently predicts local stresses around the butt weld when the maximum distortion amplitude is below 0.6×tmm. The distortion needs to be considered at least up to a length of half of the plate width from the weld location and can represent longitudinal profiles within 60% of the plate width. In conclusion, the early structural stress assessment of thin-walled panels can be significantly simplified, thus helping bridge the gap between complex numerical analysis and simplified analytical solutions.

Multi-condition classification optimization of subframe of dust suppression vehicle

In this paper, a forward classification optimization design idea for the subframe structure with discrete material distribution and take a typical subframe of a dust suppression vehicle is taken as an example to optimize and verify. Using the finite element method, we established a simulation model for the dust suppression vehicle, and the feasibility of lightweight design was determined through the multi-condition stress analysis and modal analysis of the subframe structure of the model. Firstly, the water tank bracket structure is taken as the topology optimization space, the compromise topology optimization based on grey correlation is carried out, and the conceptual design is carried out according to the material distribution of the water tank bracket shown in the topological cloud image. Then the response surface optimization model is established, and the thickness of each structure of the subframe is parameterized. Before optimization, a Pareto graph was drawn through sensitivity analysis to exclude variables with weak correlation with optimization objectives, and a high-precision response surface was fitted by least square method to meet the requirements of response surface model adaptation. Finally, the best solution was found by GRSM algorithm. After adjusting the original model according to the parameters of the best solution, the optimized subframe not only meets the operational requirements of the dust suppression vehicle but also achieves a 23.8% reduction in weight, demonstrating significant practical engineering value.

Structural Design and Stress Analysis of a Micro Aircraft Wing in a Student Competition

Structural Design and Stress Analysis of a Micro Aircraft Wing in a Student Competition

Progressive failure analysis on composite structures using a wave based method

This research examines a Progressive Damage Model for laminated composites using a wave-based technique. Using conventional numerical methodologies, such studies may require a significant amount of CPU time. Compared to standard techniques, the approach proposed can provide a quick and cost-effective evaluation. This work presents a numerical approach for dealing with periodic media subjected to an impact load that can provide damage initiate and evolution. The proposed model is based on a hybrid formulation for the wave-damage interaction that describes wave scatterings, as well as a stress analysis of a composite structure subjected to an impact force. The failure analysis is carried out by identifying the damage location and then describing the modification of the material properties of the damaged elements using Hashin’s failure criteria and material property degradation rules. A comparison of stress distribution with results from the conventional finite element approach was performed in order to confirm the hybrid WFE/FE method, and good agreement was noted. Finally, an impact on a composite beam was studied. The evolution of the structural failure is presented. This article takes into consideration material degradation over time.

Structural design and simulation study of intelligent defect elimination equipment for high‐voltage transmission line pin defects

AbstractTransmission lines may suffer from pin defects, necessitating regular patrols and maintenance. The traditional maintenance approach not only involves a substantial workload and low efficiency but also poses a threat to the safety of maintenance personnel. To address the issue of pin defects in high‐voltage transmission lines, this paper introduces the design of an intelligent pin‐eliminating robot. The research focuses on two main aspects: firstly, analyzing the transmission line environment and employing Solidworks software to design the mechanical structure of the robot. Subsequently, a static stress analysis of the robot's structure is conducted to ensure the rationality of the design. The second aspect addresses the impact of the robot on the electric field distribution of the transmission line in high electric field intensity areas and whether the robot itself experiences discharge phenomena. COMSOL simulation software is utilized to globally calculate and analyze the electric field of the robot. Research results indicate that the threshold for the curvature radius of the pin‐eliminating robot's tip is 2.5mm, and values below this threshold may lead to the occurrence of discharge phenomena. The optimized pin‐eliminating robot, under normal operation, does not exhibit discharge phenomena in a 500kV strong electric field.

Machine Vision Based The Spatiotemporal Information Identification of The Vehicle

Accurately identifying the vehicle load on the bridge plays a vital role in structural-stress analysis and safety evaluation. Also, extracting the spatiotemporal information of the vehicle’s is crucial for identifying the vehicle load. This study aimed to propose a vehicle spatiotemporal information-identification method based on machine-vision technology. First, digital video surveillance cameras were installed in the front and on the side of the monitoring section to capture real-time videos of vehicles passing through the monitoring section. The background-difference method was used to detect vehicles based on the frontal video. Subsequently, the transverse position was evaluated according to the distance between the vehicle’s license plate and the lane line. Other vehicle parameters, including the vehicle’s speed, the number of axles and the wheelbase, were identified based on the lateral video and the auxiliary lines with a known distance. Second, a laboratory model experiment and multiple field tests under different scenes were carried out to validate the efficiency and accuracy of the proposed method. The results indicated that the average identification errors of wheelbase for the model experiment and the field tests were all 1.12% and those of the vehicle’s speed were 1.25% and 1.35, respectively. Also, the average deviations of the lateral position were 2.57 mm and 2.69 cm, respectively. The variances of the identified error of the three parameters for the field tests were 0.78%, 1.83 cm and 0.54%, respectively. This verified that the proposed method has high accuracy, reliability and good anti-noise performance. KEYWORDS: Machine vision, Spatiotemporal information, Load identification, Orthotropic deck, Bridge engineering.

Rancang Bangun dan Analisis Rangka Traktor Pemanen Jagung

A corn harvesting tractor is a tractor that operates using a diesel-powered engine which is used to harvest corn and is operated by humans. It is estimated that the presence of this tractor will lighten the burden on corn farmers who previously harvested using human power. Apart from making harvesting easier, corn harvesting tractors also increase production yields. This research aims to reveal the stress values that occur in the frame and the safety values from the results of the design of the tractor frame structure in the form of design and structural strength analysis. This research was limited to a loading of 200 kg. This research examines the design, simulation, and stress analysis of the frame structure of a 200 kg corn harvester tractor using the finite element method or can be said to be Finite Element analysis (FEA). ASTM A36 Steel material is used. Finite element analysis is carried out with a numerical system using software Solidworks 2020. The results of the simulation and analysis show that the tractor frame structure has a stress, deformation, and safety factor of 1.228e+07 N/m2, 2.934e-04 m, and 20.

An elastoplastic damage model for concrete considering the influence of mesostructure on transverse deformation

The deformation of mesostructures such as micropore collapse or microcrack expansion within concrete can hugely influence its macro transverse deformation. This deformation characteristic is not effectively characterized in existing elastoplastic damage constitutive models based on micromechanics. This discrepancy can result in substantial disparities between the calculated results and the actual situation when carrying out the stress and deformation analysis of concrete structures. Through an in-depth examination of how micropore collapse and microcrack shear expansion affect transverse measurable strain, a new calculating method for concrete transverse deformation is established according to its actual evolution characteristics. The reliability of the proposed method is verified based on the triaxial compression test results. Research results indicate that the transverse deformation of concrete increases slightly before the peak deviatoric stress, and significantly in the post-peak stage. If deformation is restricted, changes in transverse deformation can profoundly affect the stress state of concrete. Micropore collapse reduces the macroscopic transverse deformation of concrete, while microcrack expansion has the opposite effect. The strain caused by micropore collapse and microcrack expansion can be deemed as derivative strain of plastic strain, and an influence coefficient can be used to characterize the impact of these two factors on macroscopic transverse deformation. It is proposed that the total transverse strain consists of elastic strain and the product of plastic strain and plastic strain influence coefficients. The development characteristics of concrete transverse deformation can be effectively captured when describing the plastic strain influence coefficient using an arctangent function.

Materials, Structure, and construction of a low-shrinkage UHPC overlay on concrete bridge deck

As ultra-high performance concrete (UHPC) has superior mechanical and durability properties, it is a promising solution to apply a thin layer of UHPC on top of normal concrete bridge decks to extend the service life and enhance the structure integrity. However, the large autogenous shrinkage characteristics of UHPC is still an issue, and there is a lack of research focus on the structural design and stress analysis of the concrete bridge deck and UHPC overlay system. Thus, this study first designs and evaluates a new low-shrinkage UHPC mixture internally cured with a high-strength, high-abrasion resistant, and porous aggregate (calcined bauxite, CB), and the optical mixture design is validated by testing the fresh, mechanical, autogenous shrinkage, abrasion, and impact properties of the UHPCs. Second, the outdoor UHPC overlay-NC composite slab experiments and the numerical modeling are carried out to analyze the shrinkage performance of the UHPC, debonding potential of the overlay layer, stress and strains development in the system. Then, the significant influencing factors and the key measures to assure the UHPC-NC interface bonding properties are obtained, including proposing a grouped L-shape steel rebar arrangement for strengthening the interface. Finally, the applicability of the new low-shrinkage UHPC mixture as overlay materials on a real concrete bridge deck is demonstrated. Based on these, the engineering design scheme and the construction recommendations of an environmentally-cured low-shrinkage UHPC overlay on concrete bridge deck is given. The utilization of UHPC overlay on concrete bridge decks offers a novel paving system that substantially enhances strength, abrasion resistance, and durability.

Performance analysis of newly designed connection rods for 100 cc petrol engine using FEA

Connecting rod is an essential component of an IC engine. The connecting rod design significantly affects the performance of IC engine. In this work, existing I-type and new X-type connecting rods was designed as per the specifications of 100 cc Honda Activa engine. The modelling and finite element analysis of both the connecting rods was carried out using SOLIDWORK® 2017–18 software. The structural stress analysis was carried out under cyclic load (i.e., tensile and compressive) of 4337.36 N. The I-type connecting rod reveals the maximum stress of 346 MPa with factor of safety of 1.56–3.15. The X-type connecting rod shows the maximum stress of 247 MPa and increased factor of safety of 1.97–3.23. The shank regions (i.e., region 3, 4 and 5) of I-type connecting rod have stresses of 346 and 191 MPa under tensile loading and 194 and 171 MPa under compressive loading. However, the similar shank regions of X-type connecting rod have reduced stresses of 247 and 167 MPa under tensile loading and 188 and 217 MPa under compressive loading. The results reveal that the X-type connecting rod has minimized stresses in the shank comparison to I-type connecting rod. These minimized stresses provide higher factor of safety and longer working life of X-type connection rod compared then the I-type connecting rod.

High Spatial Resolution Internal Stress Testing and Analysis of Fiber Optic Winding Structure Using BOTDA

This paper proposes a distributed stress analysis method for fiber winding structures. Compared with the traditional single-layer method, we quantitatively calculated each turn's stress in the fiber stacking state, including the inclination angle, endplate, and layer transition. BOTDA tested the internal stress at high spatial resolution, which is consistent with the distributed method. The results proved the attenuation of internal stress under fiber stacking state in different winding parameters. For the first time, quantitative analysis of the stress increase characteristics of layer transition has been realized. At last, the discussion of rewinding, tension dropout, and extrusion defects provides a non-destructive and rapid method for defect recognition and winding quality improvement.

Flexible Riser Tensile Armor Modelling Method and Application to Fatigue Analysis

In this paper, we present a new stress calculation method for flexible structures, particularly, tensile armors, and apply it to flexible riser fatigue analysis. The method is based on a 3-dimensional curved bar theory. First, the tensile armor center line was described as a cylindrical helix curve; its bent curve length and bending migration length were derived and studied under different friction scenarios. Second, the tensile and bending stiffness was derived with consideration of more accurate shape parameters and the frictional hysteretic effect, and verified through FEA analysis results. Third, we presented the stress calculation formula for tensile armor under tension and bending load. All stress components were considered, including tensile, bending and shear stresses. Fourth, the method was benchmarked with published experimental results on a flexible prototype tension and bending tests, and comparisons showed general agreements. Fifth, the method was applied to an in-service 8″ flexible riser for fatigue assessment and lifetime extension evaluation, and showed the flexible riser has sufficient remaining fatigue life, and is suitable to continue its service under the current operating conditions. Last, conclusions were drawn. We concluded that the presented tensile armor stress calculation method and modelling techniques are valid for flexible riser fatigue analysis. This method is time efficient, and can be implemented into other multi-scale models for riser dynamic analysis. It is also applicable to other similar helix structure stress analysis, such as wire ropes, submarine hoses, and subsea umbilicals.

Performance Improvement of Permanent-Magnet-Synchronous Motors through Rotor Shape Optimization of Marine Blowing System with High-Speed Rotation

Currently, research is being carried out on the performance improvement of permanent-magnet-synchronous motors (PMSM) used in air conditioning and blowing systems for marine, as well as structural research, regarding their high-speed operation. Surface-mounted permanent magnet (SPM) motors used in marine propulsion and air-conditioning systems have the advantages of easy rotor manufacturing and a simple structure. However, owing to the structural characteristics associated with attaching a permanent magnet to the surface of the rotor, there is a risk of permanent magnet scattering when turning a rated load at high speed, and the rotor assembly is directly affected by the heat generated in the stator winding. Therefore, in this study, additional protrusions were proposed to prevent rotor scattering during high-speed operations. Additionally, optimization was performed to reduce the torque ripple at the rated load and the total harmonic distortion (THD) of the no-load-induced electromotive-force waveform generated by the protrusion. Consequently, the risk of scattering at high speeds was improved by securing the bonding force of the permanent magnet using the proposed structure, and the THD and torque ripple were reduced compared with those of the basic model through optimization. In addition, rotor structural stress analyses were conducted to solve the problem of scattering at high speeds and eigenmode analysis.

Design, local structural stress, and global dynamic response analysis of a steel semi-submersible hull for a 10-MW floating wind turbine

Platforms for floating wind turbines cannot be designed using conventional procedures like other offshore constructions. The design of floating wind turbine platforms must consider the significant nonlinearity of the fully coupled aero-hydro-servo-elastic dynamics, which necessitates a time-domain load transfer for structural stress analysis. This article presents and verifies an effective yet practical design method for floating wind turbine platforms, which can provide reasonable internal stress for design checks. A robust design process is proposed. Following the proposed method and procedure of a 10-MW wind turbine, a steel semi-submersible platform is developed with the criterion for the steel platform’s design checks, intact stability analysis, natural period analysis, and buckling analysis executed. A tangible concept is established, along with fully coupled numerical models of the 10-MW wind turbines supported on the steel structure. The dynamic behavior of the steel platform is evaluated by accessing and comparing the dynamic performances of the concrete- and steel-support wind turbine numerical models. The key findings and conclusions from the steel platform’s design and numerical study are summarized below. In addition, future design and analysis ideas are proposed, expanding the engineering practice and research on floating wind turbine platforms.

Study on Tensile Performance of Double-Bolted Joints between Carbon Fiber Reinforced Polymer Plate and Aluminum Plate

Carbon fiber reinforced polymer (CFRP) with high specific strength, specific modulus, and other outstanding properties, which could be used in aerospace, shipbuilding, and railway. The joint of carbon fiber composite material plate and metal material plate plays an important role in the overall performance of the structure. In this paper, a carbon fiber reinforced polymer (CFRP) progressive damage model is developed based on composite laminate theory and 3D Hashian theory. The model of the double bolt single lap joint shear connection is established for the CFRP plate and the finite element method is used to carry out the stress analysis and failure prediction of the lap structure. The effect on structural performance under tensile conditions was studied through the change of double bolt spacing. The results show that the decrease in bolt row spacing can lead to the interference effect between holes. In addition, the progressive damage of the composite plate is located near the center line of the bolt hole.

Analisis Kekuatan Pembebanan Frame Pada Meja Las

Welding machine is a machine that facilitates human work in joining metals. There are two types that are usually used by humans, namely carbide welding machines and electric welding machines. Which both have their respective advantages as a metal connector. This article is lifted from the problem that occurs in the frame or frame on the welding table which experiences severe enough bending of the top frame (head support) which can damage the table frame and the unknown load (force) received by the welding table frame so that the frame is experiencing a bend. Then a design is carried out in the form of a design drawing that can be analyzed for the strength and stress that occurs in the frame which allows researchers to know the load value that is safe to use for the frame. This article aims to reveal the value of the stress that occurs in the frame and the safety value obtained from the design results of the weld table frame structure in the form of technical drawings and structural strength analysis. This article is limited to a loading of 400 newtons. This article examines the design, simulation and stress analysis of the weld table frame structure with a capacity of 400 newtons using the finite element method or also known as Finite Element Analysis (FEA). The material used is st37 iron. Finite element analysis was carried out using a numerical system using the Autodesk Inventor Professional 2020 software. The results of the simulations and also the analysis that has been carried out show that the welding table frame structure has a stress, deformation, mass, and safety factor of 20.0755 MPa, 0.0582948 mm, 40 kg

Research on the structural behavior of special-shaped arch bridges

With the social progress and the rapid development of people's economic level, people pay more and more attention to the external image of bridges, which greatly promotes the emergence and development of special-shaped arch bridges. But because of the particularity of the special-shaped arch bridge structure, its plane stress characteristics, which are different from the traditional arch bridge, become more complex. In this paper, three types of arch bridges commonly seen in special-shaped arch bridges: leaning type, inclined span type and butterfly type arch bridges are selected for a brief structural stress analysis. The results show that most of the arch structures of special-shaped arch bridges only play an auxiliary role in bearing loads, and due to the more complex stress, the finite element analysis software needs to be used to optimize the structure for many times to reach a relatively reasonable range. In addition, some arch structures are used more for aesthetic purposes than to bear loads, and their mechanical performance is basically zero.