Six-component Force Research Articles

Research on Decoupling Model of Six-Component Force Sensor Based on Artificial Neural Network and Polynomial Regression.

A two-stage decoupling model based on an artificial neural network with polynomial regression is proposed for the six-component force sensor load decoupling problem in the case of multidimensional mixed loading. The six-dimensional load categorization stage model constructed in the first stage combines 63 load category label sets with a deep BP neural network. The six-dimensional load regression stage model was constructed by combining polynomial regression with a BP neural network in the second stage. Meanwhile, the six-component force sensor with a fiber Bragg grating (FBG) sensor as the sensitive element was designed, and the elastomer simulation and calibration experimental dataset was established to realize the validation of the two-stage decoupling model. The results based on the simulation data show that the accuracy of the classification stage is 93.65%. The MAPE for the force channel in the regression stage is 6.29%, and 3.24% for the moment channel. The results based on experimental data show that the accuracy of the classification stage is 87.80%. The MAPE for the force channel in the regression phase is 5.63%, and 4.82% for the moment channel.

An experimental investigation on the aerodynamic characteristics and vortex dynamics of a flying wing

AbstractIn this paper, we present a detailed experimental investigation mainly on the vortical flow fields and the associated vortex breakdown phenomena over a non-slender flying wing (sweep angle, ${\rm{\Lambda }}$ = 53°). In the process, the aerodynamic coefficients were also determined using a six-component force balance. Surface oil flow visualisation, surface pressure measurements and particle image velocimetry (PIV) measurements, in various crossflow planes and in a longitudinal plane passing through the leading-edge vortex core, were carried out at various Reynolds numbers to understand the flow field over the non-slender flying wing. Aerodynamic characteristics of the flying wing show local peaks and valleys in the pitching moment coefficient. The surface flow visualisation reveals that the nonlinearity of the pitching moment curve is due to the complex nature of vortical flow structures. The flow visualisation also demonstrates the presence of a wave-like surface pattern, and its size is found to reduce with increasing Reynolds numbers. The present PIV measurements confirm that this wave-like surface pattern is associated with vortex breakdown phenomena. These measurements also reveal that the vortex breakdown has not reached the apex of the wing, even at post-stall angle-of-attack. For pre-stall ( $\alpha $ = 20°) flow regimes, it is observed that the location of the vortex breakdown moves downstream as the Reynolds number increases, but this influence is minimised at near-stall ( $\alpha $ = 25°) and post-stall ( $\alpha $ = 30°) flow regimes. Reconstructed velocity field using the first 10 dominant proper orthogonal decomposition (POD) modes reveals that the nature of the vortex breakdown over the flying wing is a spiral-type vortex breakdown.

Wave forces and moments on concave and vertical front caissons supported on piles

ABSTRACT The present paper details the total wave-induced forces and moments on the circular cum parabola shape (CPS-PSB) and vertical front pile-supported breakwaters (VF-PSB) through a comprehensive experimental investigation under intermediate to deep water conditions. The model was subjected to the action of random waves with peak wave periods ranging from 1s to 2.6s. The total wave forces and moments were measured using a six-component force balance. VF-PSB experiences maximum wave force at lower submergence and the vertical force decreases exponentially as relative depth increases. In the case of CPS-PSB, the variation of vertical force with relative depth is similar to the energy loss. The horizontal wave forces on both PSB models decrease with their relative submergence as the wave exposure frontal area. The induced moments are higher for longer waves and higher submergence. CPS-PSB experiences lesser force and moment than VF-PSB.

Design and Experiment of Anti-Blocking Components for Shallow Stubble Clearing Based on Soil Bin Test

In response to the problems of excessive wheat stubble blocking the opener during corn seeding in wheat–corn double cropping areas, an active-strip stubble removal method was proposed under the premise of conservation tillage. Firstly, the effects of two conventional rotary blade structures (inward and outward) on the stubble-cleaning effect and power consumption were studied under five rotary speeds (400, 500, 600, 700, 800 rpm). The results show that when the rotary speed was 400–600 rpm, the outward structure of the rotary blade was more suitable for stubble cleaning. Then, a torque sensor and a six-component force sensor were applied to the soil bin test platform to measure the relative data of four oblique angles (0°, 15°, 22.5°, 30°) on the stubble-cleaning effect, seedbed parameters, and power consumption at three rotary speeds (400, 500, 600 rpm). The results show that the straw residue on the seedbed was effectively reduced when increasing the oblique angle and rotary speed. Moreover, the quality parameters of the seedbed were improved and the power consumption was reduced when reducing the oblique angle and rotary speed. When the rotary speed was 400–500 rpm, the difference between the vertical resistance and lateral resistance was relatively small, while the difference between the horizontal resistance was large.

Improving aircraft aerodynamic performance with bionic wing obtained by ice shape modulation

For Unmanned Aerial Vehicles (UAVs) with limited electrical power to achieve effectively anti-/de-icing at the leading edge of the wing, a strategy of ice shape modulation was proposed. Isolated simulated ice shape pieces printed by 3D printing technology are mounted on a NACA0012 finite wing model, and its lift/drag coefficients and suction-side velocity fields are measured by the six-component force balance and the Particle Imaging Velocimetry (PIV), respectively. The ratio of the spanwise length of a single ice shape piece to chord length and the spanwise length of the non-icing area between the two adjacent single ice shape pieces are defined as dimensionless ice shape length (w/c) and dimensionless modulation ratio (w/λ), respectively. The results indicate that for a fixed w/λ, the wing lift coefficient first increases and then drops with increasing w/c, and a peak value exists when w/c is between 0.1 and 0.2. The lower the w/λ is, the higher the wing lift coefficient will be. The periodical variation of the flow separation area along the spanwise direction is attributed on the one hand to the acceleration effect of the flow field in the non-icing area which reduces the separation area, and on the other hand to the cross-flow caused by the streamwise vortices from the non-icing area to the icing area which promotes the mixing of the flow field (similar to vortex generators). The obtained modulation law is verified through flight tests and provides guidance for the use of ice shape modulation scheme for UAVs that cannot be completely anti-/de-icing under severe weather conditions.

Measurements of Aerodynamic Performance of the Fuselage of a Hybrid Multi-Rotor Aircraft with Autorotation Capability

The design and optimization of aircraft structures need to be accompanied by the analysis of their aerodynamics. This paper presents numerical calculations and wind tunnel tests to determine the aerodynamic characteristics of the designed unmanned aircraft. The aim of the study was to analyze the aerodynamic performance of the designed hybrid unmanned aerial vehicle and its longitudinal stability. This unique design, i.e. a hybrid aircraft which is a combination of a gyrocopter and a multi-rotor aircraft has not been the object of research yet. The research object is a 1:1 scale model created by the rapid prototyping method. The research was a computational and experimental study. The ANSYS Fluent software was used for the calculations, and the computational mesh of the developed model consisted of 3.5 million tetrahedral elements. The numerical investigations were carried out using the created CFD model with a k-ω turbulence submodel. In addition, the obtained results made it possible to numerically analyze the forces acting on the individual components of the research object, which is a valuable extension of the wind tunnel tests. The experimental studies were performed in a closed-loop subsonic wind tunnel. Aerodynamic forces and moments were measured using a six-component force balance. The obtained results were compared to validate the developed numerical model. The research values describe the performance of the research object in terms of minimum drag force coefficient, maximum lift to drag ratio, and properties related to stability.

Effects of Wind Barriers on Wind Fields and Vehicle Stability on Bridges

To explore the influence of bridge wind barriers, with their specific opening shapes and arrangements, on bridge deck wind fields and vehicle driving stability under different crosswinds, five bridge wind barrier schemes were designed. For two incoming wind speeds, the wind speed at different heights over three traffic lanes and the aerodynamic six-component force of the vehicle model were measured, and the influence of the wind barrier parameters on the vehicle driving stability was analyzed. The equivalent wind speed reduction coefficient of the wind barrier was compared with the dimensionless coefficients of the aerodynamic side force, roll moment, and aerodynamic lift to verify the accuracy of the shielding effect evaluation indices. The final conclusions provide a useful reference for designing bridge wind barriers.

Integrated Vehicle Dynamics Control Ordered by Six-Component Force at Center of Gravity with Brakes Mounted on Each Wheel

Integrated Vehicle Dynamics Control Ordered by Six-Component Force at Center of Gravity with Brakes Mounted on Each Wheel

Wind Tunnel Performance Tests of the Propellers with Different Pitch for the Electric Propulsion System.

The geometry of a propeller is closely related to its aerodynamic performance. One of the geometric parameters of a propeller is pitch. This parameter determines the distance by which the propeller moves forward during one revolution. The challenge is to select a propeller geometry for electric propulsion in order to achieve the best possible performance. This paper presents the experimental results of the aerodynamic performance of the set of propellers with different pitch values. The tests were performed in a closed-circuit subsonic wind tunnel using a six-component force balance. The analyzed propellers were 12-inch diameter twin-blade propellers that were driven by a BLDC (brushless direct current) electric motor. The tests were performed under forced airflow conditions. The thrust and torque produced by the propeller were measured using a strain gauge. The analysis was performed for different values of the advance ratio which is the ratio of freestream fluid speed to propeller tip speed. Additionally, a set of electrical parameters was recorded using the created measurement system. The propeller performance was evaluated by a dimensional analysis. This method enables calculation of dimensionless coefficients which are useful for comparing performance data for propellers.

Coupled Aeroelastic Study of a Flexible Micro Air Vehicle-Scale Flapping Wing in Hovering Flight

Instantaneous force and structural deformation experiments were performed on a flexible, structurally characterized, low-aspect-ratio representative flapping wing. A six-component force balance was used to measure aerodynamic-force time history over a flap cycle. A VICON motion capture setup tracked the wing deformations while flapping. Measured aerodynamic forces and wing deformations were compared against coupled computational fluid dynamics/computational structural dynamics (CFD/CSD) aeroelastic analysis results. The CFD solver is an unsteady Reynolds-averaged Navier–Stokes solver. The CSD solver is a general-purpose multibody dynamics solver capable of modeling geometrically nonlinear beam and shell elements. The CFD/CSD results were able to capture the overall trend in aerodynamic forces and wing deformations. Although predicted and measured variations in lift were similar, the drag-force magnitudes tended to be underpredicted by the coupled aeroelastic solver. The coupled CFD/CSD solver was used to evaluate the influence of wing flexibility on wing performance. Results showed that, in particular instances, decreasing wing stiffness increased the time-averaged aerodynamic lift and lift-to-power ratio. Decreased wing stiffness led to reduced leading-edge vortex circulation strength. This suggests that the increased wing performance is mainly due to a redirection of the resultant force vector allowed by the increased wing compliance.

A simulation based large bus side slip and rollover threshold study in slope-curve section under adverse weathers.

To study the side slip and rollover threshold of large bus in slope–curve section under adverse weather, factors that affect the safety of large buses that run in slope–curve section, such as rain, snow, cross-wind environmental factors, and road geometry, were analyzed to obtain the friction coefficient of the road surface under different rainfall and snowfall intensities through field measurements and to determine the six-component force coefficient of wind that acts on large buses through wind tunnel tests. The force analysis of large bus in slope-curve section was carried out, and the mechanical equations of large bus under the limit conditions of sideslip and rollover in slope-curve section were established. TruckSim simulation test platform was used to establish a three-dimensional road model and large bus mechanical model at a design speed of 100 km/h. Input parameters, such as cross-wind speed and road friction coefficient, simulate the impact of wind-rain/snow coupling. Under the combined action of wind-rain/snow, the operation test of large bus in slope-curve section was carried out, and the key parameters and indicators of the sideslip and rollover of large bus in slope-curve section were outputted and analyzed. The sudden change point of lateral acceleration is the judging condition for sideslip of large bus in slope-curve section under different road friction coefficient (0.2–0.7), changing from 0.15m/s2 and stabilizing to 0.52 m/s2, and a 0N vertical reaction force of the inner tire is the critical judging condition for rollover under road friction coefficient0.8, and the operating speed thresholds were proposed under different road friction coefficient. This study is expected to provide theoretical support for the speed limit of large bus in slope-curve section under adverse weather.

Evaluation of Failure Probability in Series System of Three-Axle Trucks under Strong Crosswind

The probability of wind-induced failure accidents in three-axle trucks under pulsating strong crosswinds and the corresponding critical safe speed are investigated in this study. Reliability theory and random fuzzy methods are utilized to establish the membership function of the failure probability in the series system (FPSS) composed of rollover, side-slip, and rotation failure accidents. The Kaman spectrum is used to realistically simulate the fluctuating wind time history curves of different average speeds. Four factors affecting the six-component force coefficient of the three-axle truck and the crosswind load are considered: fluctuating average wind speed, wind direction (angle), truck driving speed, and road adhesion coefficient. A three-axle truck nonlinear model is established accordingly. The model is used to obtain the dynamic response of the three-axle truck under strong crosswind conditions as per the time-varying curves of the vertical load of the truck, the time-varying curves of the lateral displacement of the center of mass, and the time-varying curves of the heading angle. An advanced Monte Carlo simulation algorithm based on importance sampling is used to determine the probability of a three-axle truck with FPSS under strong crosswinds; the given acceptable probability of failure (accident) is used to obtain the critical safety speed. The sensitivity analysis of random variables reveals that the possibility of three truck failures of the three-axle truck in strong crosswinds is, from largest to smallest, rollover, side-slip, and rotation. This research may provide useful guidance for exploring the probability of wind-induced accidents and the critical safety speeds of vehicles, as well as useful general information for road transportation management departments.

Assessing the Impact of Membrane Deformations on Wing Sail Performance

Abstract The aim of this research is to quantify the membrane deformations and their impact on performance for a ribbed wing sail. A 1m x 0.8m rectangular planform NACA0012 foil was designed to replicate a single section of a wing-sail. Two foils were manufactured based on this geometry, one out of solid foam and one using a rib and membrane structure. These were tested in the R.J. Mitchell closed return 3.6 m x 2.5 m wind tunnel at the University of Southampton. Their aerodynamic performance was assessed over a range of angles of attack using a six-component force balance showing the overall performance of the membrane wing was reduced by between 5-11% depending on the analysis conducted. A stereo camera system was used to perform Digital Image Correlation (DIC) in order to quantify the full field deformation of the membrane wing structure whilst under aerodynamic load. This showed membrane deformations of up to 15% of the section thickness. The experimental membrane displacements were then used to create a deformed wing sail geometry, removing the effect of foil bend and twist, allowing a CFD investigation of the impact of membrane deformations alone. This indicated that the static membrane deformations resulted in a decrease in performance of up to 1.3% compared to the rigid aerofoil.

Experimental investigation of serpentine nozzles for turbofan

Serpentine nozzles are widely used in stealth bombers and unmanned aerial vehicles to significantly suppress the infrared radiation signatures and to acquire excellent stealth performance with the goal to improve the survivability on the battlefield. The flow characteristics of serpentine nozzles are complex and noticeably different from those of axisymmetric nozzles due to the geometric configuration. This paper aims to obtain the flow characteristics of both serpentine nozzles and axisymmetric nozzles and to compare them under various working conditions. We obtained the flow characteristics of serpentine nozzles and axisymmetric nozzles with the employment of a schlieren system, PSI electronic pressure scanning valves, a six-component force balance system and flowmeters. The results show that the static pressure distributions on the upper and down walls of serpentine nozzles are completely different from those of axisymmetric nozzles, which are mainly affected by the flow tube near the walls. The flow velocity increases and the static pressure drops when the flow tube contracts. The outcome is opposite once the flow tube expands. The nozzle configuration and the bypass flow pressure ratio have little influence on the schlieren photographs of the flow fields downstream of the nozzle exit, which are composed of expansion waves and shock waves alternately. The values of the flow coefficient and the thrust coefficient both decrease when the difference between the core flow pressure ratio and the bypass flow pressure ratio gets large. The configuration of the serpentine nozzle, especially the wall curvature, affects the values of its flow coefficient and thrust coefficient. The value of the flow coefficient for serpentine nozzle 2 is about 1.5% lower than that for serpentine nozzle 1, and the value of the thrust coefficient for serpentine nozzle 2 is about 0.5% lower than that for serpentine nozzle 1.

Correction to: Static Calibration and Dynamic Behaviour of a Six-Component Force Balance for Variable Pressure Water Tunnel Facilities

Correction to: Static Calibration and Dynamic Behaviour of a Six-Component Force Balance for Variable Pressure Water Tunnel Facilities

Static Calibration and Dynamic Behaviour of a Six-Component Force Balance for Variable Pressure Water Tunnel Facilities

The presented six component force balance is a novel design used for many of the force measurements on hydrofoils and other bodies in the University of Tasmania’s cavitation tunnel. This balance is a versatile piece of equipment, the distribution of its six load cells gives it a high degree of sensitivity and stiffness in all directions. The accuracy of the balance in operating conditions has yet to be defined and its use for investigations of low frequency fluid-structure interactions warrants an analysis of its dynamic properties. This paper outlines a critical analysis of the balances calibration methodologies and its measurement uncertainties. A dynamic vibration model was built and validated with finite element modelling and experiment to give a prediction of the force balances natural frequencies and how they change with different test article mass and added masses. These results provide confidence in the data produced by this device and guide future experimental investigations into fluid structure interactions.

Research into integrated vehicle control ordered by six-component force at center of gravity

Research into integrated vehicle control ordered by six-component force at center of gravity

Optimal design of sensor structure based on virtual calibration test

The design of wheel six-component force sensor includes elastic body, strain gauges distribution scheme, signal acquisition and processing and so on. In this paper, the virtual calibration test is used to optimize the structure of the sensor elastic body. According to the structure and principle of the self-developed six component force sensor calibration test-bed, a set of calibration device is designed for the sensor. The stress distribution and strain output of the elastic body are obtained by finite element method. The optimization of elastic body is carried out from the requirements of material strength and coupling rate of output signal. Finally, the sensor elastic body structure which meets the strength requirements and has low coupling rate is obtained.

Study of the Difference between Single and Multi-component Calibration Results of Tire Six-component Force Sensor

The paper studies the difference between single and multi-component calibration results of tire six-component force sensor. In accordance with the measuring principle of strain gauge, the different formulas of single calibration and multi-component calibration for one strain gauge are deduced. Taking the resistance strain tire six-component force sensor with four column structure as an example, some certain channel output shows a larger error between single and multi-component calibration results, which is the integrated result of structure and measuring bridge. Because of the difference between the two results, single calibration is not better than multi-component calibration when calibrating a sensor working under multi-component force conditions. The simulation experiments of virtual single and multi-component calibrations are conducted based on Hypermesh and Abaqus. Thus, the above conclusions are confirmed by simulation results. In accordance with the verification above, a more reasonable method for tire six-component force sensor calibration is proposed in this paper.

A heavy load tire six-component force sensor

This paper presents research on design and calibration of a heavy load tire six-component force (including three forces and three moments) sensor. Differ from common tire six-component force sensor, it is designed mainly for truck tire and aircraft tire test. With a four-column structure in its elastic body, size thinning in the middle of every column is designed to get a higher sensitivity in Fy channel. Before fabricating, the ‘virtual calibration’ is carried out, which proves that the design scheme of strain gauge position and elastic body matches well with each other. For there is low crosstalk between every two output channels. The calibration experiment results are not entirely the same as that in ‘virtual calibration’, for factors such as material heat treatment, machining accuracy and the quality of pasting strain gauges increase crosstalks. With decoupling calculation, a high-accuracy heavy load tire six-component force sensor is still obtained.