Load Location Research Articles

The influence of tool rotational speed on microstructure and mechanical performance of dissimilar FSLW

FSLW is a novel solid-sate joining process in aircraft assembly technology that has offered superior welding quality to the joining of aluminum alloy. Concerning the success of FSLW light metal alloys coupled with lower operating costs due to improved energy efficiency and virtual lack of a consumable has emphasized the need to examine AA 2024-T4 and AA 7075-T6 based on different tool rotational speeds (RSs). This research examined the three important determinants of FSLW: cross-section morphology, microstructure behavior, and mechanical performance (lap shear failure load and fracture location) to realize the quality and reasonable experiment of the welding technique. The cross-section of the lap joint is investigated in this experiment; it is evident that the maximum temperature is found in the stir zone, and the shape looks like a bowl type. Further, it is found that tool RS does not have an influence on the effective sheet thickness, but it influences the effective lap width. With the increased RS, the effective lap width increased first and then decreased. Concerning grain size analysis, the bigger grain size was observed in the heat-affected zone, and the smaller grain size was observed in the thermomechanical-affected zone. According to the mechanical performance analysis, the lap shear failure load increased and then reduced with increased RS.

Sparse Bayesian technique for load identification and full response reconstruction

Most load identification methods require that the load location is known in advance. A sparse Bayesian framework is proposed in this study to identify the force location and time history simultaneously and then reconstruct the responses with consideration of the uncertainties of the input force and response measurement. The prior distribution of the unknown forces is assumed to be the product of multiple independent Gaussian distributions of each individual potential force. Then, the most probable values of the unknown forces, measurement noise, and variances of the forces are derived and iteratively calculated by a self-adaptive posterior maximization strategy. In such a way, the estimated force vector is nonzero merely at the positions where loads are applied, and it thus possesses the sparsity in space. Consequently, the input forces are located and quantified simultaneously, and the full-field structural responses are sequentially reconstructed with suppressed uncertainties. The proposed approach is applied to numerical and experimental examples. The results demonstrate that the technique is able to identify the force and reconstruct the responses accurately.

Radiological Investigation of Guinea Pig (Cavia porcellus) Lumbar Vertebral Morphology ‒ A Biomechanical Aspect

Abstract Numerous studies are based on the use of animal models; however, in bipedal and tetrapedal organisms there are significant differences in the biomechanics of the spinal column, which can significantly impair the quality and applicability of the results obtained. The aim of this study is to obtain basic data on the morphometric parameters of guinea pig lumbar vertebrae, the analysis of which will indicate the location of the biggest mechanical load. The lumbar vertebra morphometry test was performed by means of X-ray imageing obtained from 12 guinea pigs, with equal numbers of males and females. The results of investigations show that guinea pig lumbar vertebrae have an irregular trapezoid geometry and that the measured body lengths of L4 and L5 are the largest. The height parameters determined in the medial level showed that L4 had the most concave body. Moreover, L4 had the greatest depth of the spinal canal at the same measurement level. Consequently, in guinea pigs, the greatest load is in the L4 region, unlike in humans, where, due to the axial load of the spinal column, the highest pressure is exerted on the last lumbar vertebrae.

Modeling and Analysis of Utilizing Cryptocurrency Mining for Demand Flexibility in Electric Energy Systems: A Synthetic Texas Grid Case Study

The electricity sector is facing the dual challenge of supporting increasing level of demand electrification while substantially reducing its carbon footprint. Among electricity demands, the energy consumption of cryptocurrency mining data centers has witnessed significant growth worldwide. If well-coordinated, these data centers could be tailor-designed to aggressively absorb the increasing uncertainties of energy supply and, in turn, provide valuable grid-level services in the electricity market. In this paper, we study the impact of integrating new cryptocurrency mining loads into Texas power grid and the potential profit of utilizing demand flexibility from cryptocurrency mining facilities in the electricity market. We investigate different demand response programs available for data centers and quantify the annual profit of cryptocurrency mining units participating in these programs. We perform our simulations using a synthetic 2000 bus ERCOT grid model, along with added cryptocurrency mining loads on top of the real-world demand profiles in Texas. Our preliminary results show that depending on the size and location of these new loads, we observe different impacts on the ERCOT electricity market, where they could increase the electricity prices and incur more fluctuations in a highly non-uniform manner.

A Novel Approach of Voltage Sag Data Analysis Stochastically: Study, Representation, and Detection of Region of Vulnerability

A voltage sag is a major power quality problem at any load location, mainly due to short circuit faults. Its effects are especially clear in the industrial sector because they lead to direct financial losses. The first and most important step to getting rid of or at least reducing voltage sag is to find the places in the network where it can happen. So, this article discusses a creative way to find the weak spots in a network where the voltage is more likely to drop. This innovative strategy is based on correlation and a stochastic normal probability distribution. The voltage sag is evaluated using an analytical method. The method simulates the number, type, and location of faults randomly throughout the system. After gathering voltage dip data, it is analyzed using normal probability distribution and correlation concepts. The correlation concept provides the relationship between the sag frequency and other parameters, and the sag occurrence area was indicated by the normal probability distribution. After that, the region of vulnerability (ROV) is developed using the ROV flow chart. This paper uses an IEEE 30-bus RTS system as a case study to demonstrate the usefulness of the suggested strategy using MATLAB software.

Experimental and Numerical Investigation of the Mechanical Properties of 3D-Printed Hybrid and Non-Hybrid Composites

Recent research efforts have highlighted the potential of hybrid composites in the context of additive manufacturing. The use of hybrid composites can lead to an enhanced adaptability of the mechanical properties to the specific loading case. Furthermore, the hybridization of multiple fiber materials can result in positive hybrid effects such as increased stiffness or strength. In contrast to the literature, where only the interply and intrayarn approach has been experimentally validated, this study presents a new intraply approach, which is experimentally and numerically investigated. Three different types of tensile specimens were tested. The non-hybrid tensile specimens were reinforced with contour-based fiber strands of carbon and glass. In addition, hybrid tensile specimens were manufactured using an intraply approach with alternating carbon and glass fiber strands in a layer plane. In addition to experimental testing, a finite element model was developed to better understand the failure modes of the hybrid and non-hybrid specimens. The failure was estimated using the Hashin and Tsai-Wu failure criteria. The specimens showed similar strengths but greatly different stiffnesses based on the experimental results. The hybrid specimens demonstrated a significant positive hybrid effect in terms of stiffness. Using FEA, the failure load and fracture locations of the specimens were determined with good accuracy. Microstructural investigations of the fracture surfaces showed notable evidence of delamination between the different fiber strands of the hybrid specimens. In addition to delamination, strong debonding was particularly evident in all specimen types.

Research on Power Grid Short-term Load Forecasting Method Based on Data Mining

Because the abnormal location of the power grid load is mismarked, the average relative error increases in the process of forecasting. This paper proposes to study and analyze the method of short-term load forecasting based on data mining. It preprocesses the load characteristic clustering and related data, marks the abnormal position of a power grid within a calibrated mining range according to the load fluctuation state, and defines the short-term load forecasting range. It also constructs a data mining power load forecasting model through the acquired real-time forecasting data and information, designs layered and staged load forecasting links, and corrects and calculates by adopting data mining. The prediction residual error is obtained. The stage prediction standard is further determined, and the prediction processing is realized. The final test results show that the data mining short-term load forecasting test group designed in this paper has a small fluctuation range, indicating that the prediction error has been greatly controlled in the practical application process. The prediction error is small, the accuracy is improved, and it has practical application value.

Pushing the Performance Limit of Cu/CeO2 Catalyst in CO2 Electroreduction: A Cluster Model Study for Loading Single Atoms

Pushing the performance limit of catalysts is a major goal of CO2 electroreduction toward practical application. A single-atom catalyst is recognized as a solution for achieving this goal, which is, however, a double-edged sword considering the limited loading amount and stability of single-atom sites. To overcome the limit, the loading of single atoms on supports should be well addressed, requiring a suitable model system. Herein, we report the model system of an ultrasmall CeO2 cluster (2.4 nm) with an atomic precise structure and a high surface-to-volume ratio for loading Cu single atoms. The combination of multiple characterizations and theoretical calculations reveals the loading location and limit of Cu single atoms on CeO2 clusters, determining an optimal configuration for CO2 electroreduction. The optimal catalyst achieves a maximum Faradaic efficiency (FE) of 67% and a maximum partial current density of -364 mA/cm2 for CH4, and can maintain high CH4 FE values over 50% in a wide range of applied current densities (-50 ∼ -600 mA/cm2), exceeding those of the reported catalysts.

Dynamic crushing characteristics of bio-inspired minimal surface primitive structures

It has been proven that the triply periodic minimal surface structures (TPMS), a specific type of bio-inspired structures classified as cellular structures with continuous non-self-intersecting surfaces, have excellent energy absorption capability. However, the dynamic crushing characteristics of the TPMS have not been well comprehended. The dynamic response of minimal surface primitive structures under different crushing speeds is numerically investigated in this study. The dynamic crushing stresses of the primitive structure at the loading location and stationary side are measured to investigate the dynamic effect due to the shock wave propagation. Furthermore, the influences of other parameters, i.e., the crushing speed, relative density, and strain rate effect on the crushing stress are also discussed. The obtained results indicate that the plateau stress at the loading location is highly sensitive to the crushing speed while the opposite trend is observed for the plateau stress at the stationary side. It is also found that the primitive structures tend to deform following four distinct mode shapes, i.e., “X” mode, “K” mode, “I1” and “I2” mode, which are dependent on the crushing speed and relative density. Moreover, the energy absorption efficiency is used to define the densification strain, which shows no clear relationship with the relative density. Finally, the empirical models based on the shock wave theory and previous empirical model of honeycomb structures are developed to predict the plateau stress at the loading location and stationary side with/without strain rate effect. The predictions of the proposed analytical models agree well with the numerical results.

МЕТОДИКА ОПРЕДЕЛЕНИЯ КОРРЕЛЯЦИОННОЙ ФУНКЦИИ НАПРЯЖЕНИЯ НА ШИНАХ ТЯГОВОЙ ПОДСТАНЦИИ ПОСТОЯННОГО ТОКА

The voltage level on the rectified current busbars of a traction substation is random and depends on voltage fluctuations in the primary power system and the substation current. The operation process of an electrified railway is characterized by a continuous change in the location, number and magnitude of loads which determine the currents of traction substations. Numerous observations and studies have shown that the voltage on the DC busbars of traction substations could be estimated only on the basis of statistical probabilistic methods using the apparatus of random functions. Therefore, to estimate the voltage on 3.3 kV busbars in the first approximation, a normal random process with an ergodic property could be applied, for which it is necessary to determine the voltage correlation function.

A importância da distribuição da carga oclusal de forma adequada para a correta biomecânica de prótese parcial fixa implantosuportada: análise das tensões em implantes, componentes protéticos e infraestruturas

ABSTRACT Objective: The present study analyzed the biomechanical behavior of the generated stress on the external surface of the rehabilitation elements (implants, components and infrastructures) according to different occlusion patterns on a fixed partial denture on osseointegrated implants. Method: The experimental groups varied according to the location of the occlusal load applied to the Fixed partial denture, with a total occlusal load of 750N in all groups, opting for greater loads on the occlusal table of the molar in relation to the premolar. This evaluation was performed by the finite element method with simulations by the AnsysWorkbench 16.0 Software program. Results: The results analyzed for implants and their components showed that the more posterior the occlusal loading, the greater the stress developed (group 4), always in the connection area between the prosthetic component and the implant, as this location can induce greater screw loosening. The results analyzed for the infrastructures showed that the most distributed occlusal loading possible (group 1) is the best situation for generating less stress. However, even in group 3 which obtained the highest stresses in the critical area of the prosthetic connection, the zirconia flexural strength values generated were not worrisome. Conclusion: It can be concluded that the occlusal adjustment of Fixed partial dentures are preponderant and decisive factors for correct biomechanics and preservation of the system in the long term in order to avoid possible damage and/or failures, and exert significant and notorious differences in the behavior of all structures studied herein.

Influence of external load on forced vibration of rectangular plate

Rectangular plate is one typical structure with wild application in engineering, and the force vibration is the basis for analysis of sound radiation of plate. In this work, numerical simulation is conducted for force vibration of rectangular plate, and the influence of external load is also studied. Numerical results show that, the rectangular plate will resonate under external load at certain driven frequency, and it’s strictly related to structural modal frequencies. Structural vibration response will change obvious with the change of location of external load. When the location is fixed, with the increase of action region of external load, the acceleration of plate will decrease and some new resonance frequencies will be observed. Conclusions here will lay foundation for further work on sound radiation of plate.

Sound radiation of a GLARE panel at elevated temperature

In this work, the effect of nodal and anti-nodal shifts on the sound radiation pattern of a uniformly heated square baffled GLARE panel is analyzed. The panel is examined with a 1 N harmonic force at the center and offset locations under elevated temperature using the finite element method. The effect of load location and temperature on sound radiation pattern is computed using Rayleigh integral method. It is observed that the panel's natural frequencies reduced with an increase in temperature and changes in sound radiation pattern due to modes nodal and anti-nodal shift.

Estimating the elastic modulus and bending stiffness of steel ruler with crack using three-point bending test

Cracks are the early signs of distress in structures and must be diagnosed accurately. They reduce the structural stiffness, strength, and may adversely affect the behavior of the structure. This study aims to estimate the elastic modulus and the bending stiffness of a steel ruler with varying crack lengths. A low cost and simple three-point bending test was used for the measurements. A pristine ruler and rulers with three different crack lengths were subjected to loads of up to 6 kg (roughly 13 lbs) and the displacement close to the load location was measured. The load and displacement at the center of the specimen, for loading and unloading, were measured at equal load steps. The effect of a crack on the elastic modulus and the bending stiffness was compared with that of the pristine ruler. Permanent deformation was observed on the 10 mm and 15 mm crack ruler. The presence of crack reduced the elastic modulus of the ruler by 14% and the bending stiffness by 26.5%. The structural load-bearing capacity depends on the presence of cracks. Anticipating the extent of reduction in elastic modulus and bending stiffness aids designers in minimizing the need for repeated design revisions. This investigation supports both structural designers in designing structures such as airplanes and bridges, as well as repair technologists in upgrading existing structures.

Occlusal load and biomechanics of implant-supported fixed partial dentures: bone stress analysis

Osseointegration emerged in the 1950s, created by Per-Ingvar Branemark, when it was conceptualized as an intimate connection between the implant and the surrounding bone, and with this discovery, it was proposed as a treatment for total or partial edentulism. implants supported. Excessive loads generated by poor adjustment of occlusal forces are recurrent and common, and may generate resorption in the supporting bone; in situations of excess occlusal load, when these loads are distributed at different intensities, on different dental occlusal tables, could this be a reason for the failure of implant-supported rehabilitation? What about the absence of occlusal loading? Could this be a reason for the failure of implant-supported prosthetic rehabilitation? What will be the way to avoid exacerbated stress on occlusal tables, leading to a better generation of treatment prognosis, especially in cases of Fixed Partial Dentures (FPD) with suspended artificial teeth? This study aims, using the finite element methodology, to build a clinical situation of an implant-supported partial denture (FPD) of fixation of 3 elements of regular length, where the location of the occlusal loads (newtons) (total 750N) in the (FPD) ( Fixed Partial Denture) defined in the experimental groups, with higher loads being selected on the occlusal surface of the molar tooth in relation to the premolar, and with different occlusal forces on adjacent teeth, according to an occlusal load proposed in the research. Thus, the occlusal load was distributed, in different intensities, between each tooth of the CAD (Computer Aided Design) model. The biomechanical behavior and stresses of the fragile structures analyzed vary according to the occlusal load exerted and, therefore, controlling such occlusal loads is very relevant. The tensions are always greater and more evident in the posterior regions, whether in the cortical bone or in the medullary bone, especially when occlusal loads are applied unevenly with overload on the posterior elements of the fixed partial denture; therefore, one should always try to preserve these more distal elements.

Effect of snap-through force location on morphing of bistable variable stiffness laminates

Unsymmetric composite laminates exhibit two or more stable states due to the presence of residual thermal stresses induced during the curing process. The paper aims to exploit the possibility of assessing the morphing behaviour of bistable composite laminates using semi-analytical and numerical models. A Rayleigh-Ritz based semi-analytical model is used to investigate the variable stiffness (VS) bistable laminates generated using curvilinear fibre alignments. The obtained results are verified using a fully non-linear numerical model developed in a commercially available finite element package. In order to identify the influence of loading location on the snap-through behaviour, a parametric study is proposed in the present research. Snap-through is achieved through transverse point loads. The novelty of this work resides on the investigation of load application location on the snap-through action where the transverse load is applied at various locations on the lamina surface. Earlier research on the morphing of bistable square composites is mainly on the application of concentrated load at the centre of the laminate geometry, which is considered as an ideal location for snap-through action. The designer may also have to choose other locations for the application of snap-through loads since the lamina centre may not be appropriate always in structural applications. Four different loading locations are selected for the present analysis, and snap-through loads are calculated to check the effect of loading location. Parametric studies are performed using the proposed semi-analytical and numerical models to investigate the effect of selected loading point positions on the snap-through process. The analysis is extended to a selected VS laminate family to understand the influence of loading point positions on the curvilinear fibre alignments.

Blast Mitigations of Mid rise structural systems by using Base Isolations

Shelter is a basic need for living creatures. The shelter should be safe and secure. The damage of the shelter occurs due to natural hazards and manmade activities. Natural hazards such as earthquake, volcanic eruptions, landslides, flood, etc. Manmade activities may be accidental or intentional. Accidental activities include, internal explosions such as chemical reactions occurring at nuclear power plants, mining, rock cutting etc, gas explosions leakage etc. Hence while designing the structure, additional precautions and considerations should be taken to resist the unpredictable load. Boatload is a dynamic and impulse loads. The earth load occurs in seconds, In the height of the structures force are distributed and is proportion to mass concentrations, the blast load occurs in milli seconds that is one thousand shorter than the earthquake load and magnitude and locations of the blast load rather than mass the force is concentrated. In the present study Five storey structural system exposed to blast load is considered. MATLAB simulation technique is used in the analysis of the Five storey structural The load is acting on the structural system are calculated. Base isolations method is one the recent method is used to reduce the response of the structural system. The semi active control system is used in the analysis. The response is reduced by considerable amount by using Base isolation.

Reflective crack initiation of asphalt overlays on jointed concrete pavement using finite element model

ABSTRACT In this study, a three-dimensional (3D) finite element model (FEM) consisting of an asphalt concrete (AC) overlay on top of jointed plain Portland cement concrete (PCC) slabs was developed to investigate the mechanism of the crack initiation of traffic-induced reflective cracking. Strain values at the bottom of AC overlay were the primary response obtained from the simulation results to represent the damage induced in the AC layer. Different bonding situations between the two layers, traffic load locations, material properties and thicknesses of the AC layer were taken into consideration. The analysis results show that the dominating strain for damage is dependent on the bonding condition between the AC and PCC layers. When the AC layer is completely bonded with the PCC layer, the damage will initiate firstly at the top of the joint corner between the PCC slabs to deteriorate the bonding, then the AC bottom will be susceptible to bending strain. It was observed that the most critical load location for modeling the case of fully bonded overlays is related to the AC thickness while in the case of partially bonded overlays, the most critical load location is always located on the top of one side of the PCC joint.

Nonlinear patch resistance performance of hybrid titanium-clad bimetallic steel plate girder with web opening

Titanium-clad bimetallic steel (TCBS) is a new type of structural steel, which consists of TA1 cladding with outstanding corrosion resistance and Q235 mild steel base with good mechanical properties. Corrosion weakens the thickness of plates in steel members, which reduces the resistance capacity. The web thickness of the plate girder is relatively thin. Hence, the web is more prone to be weakened due to corrosion. To resolve the above issue, an innovative configuration of introducing TCBS into the plate girder as the web was proposed. The monotonic tensile coupon test results stated that TCBS has no evident yield plateau in its stress-strain curve. An experiment was conducted to investigate the nonlinear resistance performance of the hybrid TCBS girder under patch loading. After the experiment, the wave bending deformation of the web exhibited an axisymmetric distribution, where a tensile field was formed. The plastic hinge was formed in the loading area on the flange. No delamination or cracking in the TCBS was observed. A numerical modeling method for the hybrid TCBS plate girder under patch loading was established. Subsequently, a parametric study of the hybrid TCBS plate girder under patch loading was conducted using the proposed numerical modeling method. The effects of the material model, web opening location, web aspect ratio, height–thickness ratio, and loading location on the resistance behavior of the hybrid TCBS plate girder were thoroughly investigated.

Using musculoskeletal modelling to estimate knee joint loading pre and post high tibial osteotomy

BackgroundBoth medial knee osteoarthritis and associated varus alignment have been proposed to alter knee joint loading and consequently overloading the medial compartment. Individuals with knee osteoarthritis and varus deformity are candidates for coronal plane corrective surgery, high tibial osteotomy. This study evaluated knee loading and contact location for a control group, a pre-surgery cohort and the same cohort 12 months post-surgery using a musculoskeletal modelling approach. MethodsJoint kinematics during gait were measured in 30 knee osteoarthritis patients, before and after high tibial osteotomy, and 28 healthy adults. Using a musculoskeletal model that incorporated patient-specific mechanical tibial femoral angle, the resulting muscle, ligament, and contact forces were calculated and the medial - lateral condyle load distribution was analysed. FindingsSurgery changed medial compartment contact force throughout stance relative to pre-surgery. This reduction in medial compartment contact force pre- vs post-HTO is observed despite a significant increase in post-surgery walking speed compared to pre-HTO, where increased speed is typically associated with increased joint loading. InterpretationThis study has estimated the effects of high tibial osteotomy on knee loading using a generic model that incorporates a detailed knee model to better understand tibiofemoral contact loading. The findings support the aim of surgery to unload the medial knee compartment and lateralise joint contact forces.