Magnitude Of Acceleration Research Articles

Improving Precise Orbit Determination of LEO Satellites Using Enhanced Solar Radiation Pressure Modeling

AbstractPrecise orbit knowledge is a fundamental requirement for low Earth orbit (LEO) satellites. High‐precision non‐gravitational force modeling directly improves the overall quality of LEO precise orbit determination (POD). To address the potential systematic errors in solar radiation pressure (SRP), we introduce observed radiation data and modeled physical effects to describe the real in‐flight environment of satellites. Time‐dependent solar irradiance data and a highly physical shadow model are considered for SRP modeling. We develop an advanced thermal reradiation model for satellite solar panels. A set of improved non‐gravitational force models is performed for LEO POD, and we discuss the benefits of the enhanced dynamic models on orbit quality and dependence on empirical parameters. The Gravity Recovery and Climate Experiment Follow‐On (GRACE‐FO), Jason‐3, and Haiyang‐2B missions are selected for the POD process. Estimated empirical acceleration and scale parameters and independent satellite laser ranging (SLR) are used to validate the final orbit solutions. The magnitude of empirical acceleration estimated in POD is reduced by 19% with the enhanced dynamic modeling, and the estimated scale factor for the SRP converges to stable and reasonable level. Furthermore, the steady‐state temperature model used in thermal reradiation can effectively reduce mismodeled effects in the SRP, and the systematic linear dependency revealed by the SLR residuals is significantly reduced for the GRACE‐C and Jason‐3 satellites, with improvements of approximately 61% and 49%, respectively. Overall, advances are made in the explicit modeling of non‐gravitational forces to pursue superior satellite orbits, suggesting a more dynamic orbit solution.

Investigation of chemoconvection in vibration fields.

This study is devoted to the investigation of the chemoconvection in a two-layer miscible system caused by the neutralisation reaction proceeding in the convective-controlled (CC) regime under the influence of vertical vibrations. The CC regime without vibrational influence is characterized by the development of a density wave and vigorous convection in the upper layer, ensuring a high reaction rate and forcing the reaction front to move downwards more rapidly than in the well-known diffusive-controlled (DC) regime. It is shown that vibrations lead to some deceleration of the convection that depends both on the magnitude of the vibrational acceleration and on the initial concentrations of the reagents. Analysis of the system behaviour depending on the dimensionless parameters is carried out. It is demonstrated that the theory of thermal vibrational convection may be applied for reacting systems on quasi-steady time intervals.

Повышение надежности измерения ускорений при виброиспытаниях

The paper analyzes some causes of distortion of the set and measured vibration parameters during testing of equipment on an electrodynamic vibration stage. In particular, the influence of the joints of the mating surfaces on the vibration stand – a transition table and a transition table – a device for vibration is determined. An idealized model of the junction of two surfaces is proposed, which can be theoreti-cally described using the theory of generalized conductivity of heterogeneous structures. The joint is represented as a matrix of metal with inclusions of voids, represented as components of a mixture having infinite conductivity. A relation is derived showing that the elasticity model of the two metal surfaces joint is approximately 30 % less than that of a homogeneous metal. The obtained theoretical conclusions substantiate the recommendation to increase the rigidity of the mechanical system "vibration stand table - transition table – device for vibration tests" by introducing a thin (40...80 microns) polyethylene film into the joints. The fundamental reason for the difference in the measurement of the vibration acceleration magnitude at different control points is shown – the presence of a tipping moment in the mechanical system. Elimination of a methodological error during vibration tests is possible when controlling the vibration stand not by a real, but by a conditional control point. Recommendations on the choice of a conditional control point for the vibration stand during vibration tests of the equipment are given and justified.

Optimization on Linkage System for Vehicle Wipers by the Method of Differential Evolution

We consider an optimization problem on the maximal magnitude of angular acceleration of the output-links of a commercially available center-driven linkage system (CDLS) for vehicle wipers on windshield. The purpose of this optimization is to improve the steadiness of a linkage system without weakening its normal function. Thus this optimization problem is considered under the assumptions that the frame of the fixed links of linkage system is unchanged and that the input-link rotates at the same constant angular speed with its length unchanged. To meet the usual requirements for vehicle wipers on windshield, this optimization problem must be solved subject to 10 specific constraints. We expect that optimizing the maximal magnitude of angular acceleration of the output-links of a linkage system would also be helpful for reducing the amplitudes of sound waves of wiper noise. We establish the motion model of CDLS and then justify this model with ADAMS. We use a “Differential Evolution” type method to search for the minimum of an objective function subject to 10 constraints for this optimization problem. Our optimization computation shows that the maximal magnitude of angular acceleration of both output-links of this linkage system can be reduced by more than 10%.

Determination of strain rate dependence at intermediate strain rates using acceleration information

Precise stress-strain characteristics of materials for intermediate strain rates need to be utilized for analyzing various events in industry such as metal forging, sheet metal forming in manufacturing processes and automotive crash tests. However, the accurate evaluation of the load is not easy at intermediate or high strain rates, owing to the inertial effect. The present study aims at characterizing the hardening behavior using acceleration data without utilizing the load information with an application to a dual-phase DP980 steel sheet sample. Virtual measurements were obtained from a finite element model to check for the minimum acceleration magnitude necessary for stable identification. The same identification procedure as that used for the experiments was adopted. Also, a high-speed tensile testing equipment for steel sheet specimens was modified to increase the acceleration magnitude to implement the proposed methodology experimentally. The virtual fields method was chosen as an inverse tool to determine the strain-rate dependence of the sheet metal specimens. The stress–strain curve of an advanced high-strength steel at intermediate strain rates obtained from the acceleration was compared with the curve from the load data, and promising results were obtained.

All devices are not created equal: Simultaneous data collection of three triaxial accelerometers sampling at different frequencies

The surge of wearable device technology has enabled out-of-the-lab collection of running gait data for commercial, clinical, and coaching applications. However, low sampling frequencies interfere with measuring peak acceleration magnitudes accurately, and the ability to track relative changes during a prolonged run with lower sampling devices is unknown. The purposes of this study were to compare peak resultant acceleration measured simultaneously at different sampling frequencies and evaluate if different sampling frequencies could track similar relative changes in peak acceleration over a 20-min treadmill run. Seventeen participants ran on a treadmill at a self-selected, “easy” pace for 20-min (mean ± SD = 2.6 ± 0.4 m s−1). Three research-grade, triaxial accelerometers (“HiRes” = 1200 Hz, “MedRes” = 462 Hz, and “LoRes” = 100 Hz) were secured to each of three anatomical locations (tibia, low-back, forehead). Mean peak resultant accelerations from each device during minutes 3 to 18 were compared within each location (linear mixed model, α = 0.050). No significant device by timepoint interaction was observed ( p > 0.999). A significant main effect of sampling frequency at all three locations (HiRes > MedRes > LoRes; p < 0.001) confirmed the underestimation of low sampling frequencies on peak resultant acceleration. However, the significant main effect of time indicated that peak resultant acceleration changed similarly over time between sampling frequencies at the tibia ( p = 0.010) and head ( p = 0.002), but not the low-back ( p = 0.318). Downsampling HiRes to 400 and 100 Hz reduced the underestimation of the resultant peaks within the MedRes and LoRes signals by <7.7% across anatomical locations. This study confirms sampling frequency of wearable devices significantly affects peak resultant acceleration and demonstrates these effects are greater for signals captured at lower sampling frequencies and caudal locations. Despite these effects, this study cautiously supports the use of ≥100 Hz sampling frequencies for within-individual peak resultant acceleration tracking during “easy” prolonged runs for research, clinical, and coaching applications.

Differences in head impact biomechanics between playing positions in Canadian high school football players

ABSTRACT The objective of this study was to compare head impact magnitudes and time between impacts among positions in Canadian high-school football. Thirty nine players from two high-school football teams were recruited and assigned a position profile: Profile 1 (quarterback, receiver, defensive back, kicker), Profile 2 (linebacker, running back), and Profile 3 (linemen). Players wore instrumented mouthguards to measure peak magnitudes of linear and angular acceleration and velocity for each head impact throughout the season. A principal component analysis reduced the dimensionality of biomechanical variables, resulting in one principal component (PC1) score assigned to every impact. Time between impacts was calculated by subtracting the timestamps of subsequent head impacts within a session. Significant differences in PC1 scores and time between impacts occurred between playing position profiles (ps<0.001). Post-hoc comparisons determined that PC1 was greatest in Profile 2, followed by Profiles 1 and 3. Time between impacts was lowest in Profile 3, followed by Profiles 2 and 1. This study delivers a new method of reducing the multidimensionality of head impact magnitudes and suggests different Canadian high-school football playing positions experience different head impact magnitudes and frequencies, which is important for monitoring concussion and repetitive head impact exposure.

Pilot Collection and Evaluation of Head Kinematics in Stock Car Racing.

The goal of this work was to collect on-track driver head kinematics using instrumented mouthpieces and characterize environmental exposure to accelerations and vibrations. Six NASCAR drivers were instrumented with custom-fit mouthpieces to collect head kinematic data. Devices were deployed at four tracks during practice and testing environments and configured to collect approximately 11 min of linear acceleration and rotational velocity data at 200 Hz. This continuous data collection, combined with film review, allowed extraction of complete laps of data. In addition to typical data processing methods, a moving-point average was calculated and subtracted from the overall signal for both linear acceleration and rotational velocity to determine the environmental component of head motion. The current analysis focuses on 42 full laps of data collected at four data collection events. The number of laps per track ranged from 2 to 23. Linear acceleration magnitudes for all 42 laps ranged from 2.46 to 7.48 g and rotational velocity ranged from 1.25 to 3.35 rad/s. After subtracting the moving average, linear acceleration ranged from 0.92 to 5.45 g and rotational velocity ranged from 0.57 to 2.05 rad/s. This study has established the feasibility of using an instrumented mouthpiece to measure head kinematics in NASCAR and presented a technique for isolating head motion due to cornering acceleration from those due to short-term perturbations experienced by the driver.

Adaptive Inertial Sensor-Based Step Length Estimation Model

Pedestrian dead reckoning (PDR) using inertial sensors has paved the way for developing several approaches to step length estimation. In particular, emerging step length estimation models are readily available to be utilized on smartphones, yet they are seldom formulated considering the kinematics of the human body during walking in combination with measured step lengths. We present a new step length estimation model based on the acceleration magnitude and step frequency inputs herein. Spatial positions of anatomical landmarks on the human body during walking, tracked by an optical measurement system, were utilized in the derivation process. We evaluated the performance of the proposed model using our publicly available dataset that includes measurements collected for two types of walking modes, i.e., walking on a treadmill and rectangular-shaped test polygon. The proposed model achieved an overall mean absolute error (MAE) of 5.64 cm on the treadmill and an overall mean walked distance error of 4.55% on the test polygon, outperforming all the models selected for the comparison. The proposed model was also least affected by walking speed and is unaffected by smartphone orientation. Due to its promising results and favorable characteristics, it could present an appealing alternative for step length estimation in PDR-based approaches.

Evaluating Simple Objective Metrics for the Remote Measurement of Physical Activity: Preliminary Results from the RADAR‐AD Study

AbstractBackgroundHigher physical activity is associated with better global cognition and a lower risk of dementia (Rojer et al., 2021). Using questionnaires to assess physical activity is difficult in an Alzheimer’s disease (AD) population, since questionnaires rely on retrospective subjective recall. Wearables measure physical activity objectively and continuously. A variety exists, with some delivering raw high‐frequency research‐grade movement data, others providing summary variables only. The aim of this study is to compare simple activity metrics from two activity trackers monitoring physical activity in AD, and relate these to standard questionnaires.MethodParticipants in the RADAR‐AD study (Remote Assessment of Disease and Relapse – Alzheimer’s Disease) were asked to wear two activity trackers (dominant hand: Axivity AX3, non‐dominant hand: Fitbit Charge 3) for 8 weeks. Features calculated from the Axivity’s raw accelerometer data were: acceleration magnitude, time spent in sedentary, light, moderate‐to‐vigorous activity, and sleeping. Fitbit features included: step count and heart rate. Self‐reported activity levels (Godin Leisure Time Questionnaire), depression (Geriatric Depression Scale), social functioning (Social Functioning Scale), global cognition (Mini‐Mental State Examination), partner‐reported function (ADCS‐ADL) and neuropsychiatric symptoms (Neuropsychiatric Inventory) were assessed and related to activity levels using regression models.ResultWe included amyloid negative controls (n = 36) and amyloid positive preclinical (n = 13), prodromal (n = 15) and mild‐to‐moderate (n = 10) AD participants (Table 1). Expected associations were found between sedentary activity time and age, and between self‐reported activity and both moderate‐to‐vigorous activity time and step count (Table 2, Figure 1). Small group sizes currently make further comparisons of exploratory value only.ConclusionWearable devices have the potential to accurately capture clinically relevant aspects of daily activity and function of interest in AD population. On‐going research in the RADAR‐AD study will focus on developing disease‐specific methods of feature extraction based on raw movement data, and combining features from multiple devices, to explore this further.This work has received support from the EU/EFPIA Innovative Medicines Initiative Joint Undertaking (grant No 806999). www.imi.europa.eu. This communication reflects the views of the RADAR-AD consortium and neither IMI nor the European Union and EFPIA are liable for any use that may be made of the information contained herein.

On the accuracy limits of misspecified delay-Doppler estimation

This work derives compact closed-form expressions of the misspecified Cramér–Rao bound and pseudo-true parameters of time-delay and Doppler for a high dynamics signal model. Those expressions are validated by analyzing the mean square error (MSE) of the misspecified maximum likelihood estimator. A noteworthy outcome of these MSE results is that, for some magnitudes of acceleration and signal-to-noise ratios, neglecting the acceleration is beneficial in the MSE sense. The variance performance improvement is obtained at the cost of a systematic error in the true parameter estimation. This can be seen as a specific case of the trade-off between bias and variance. Neglecting the acceleration can improve the Doppler estimation when the error induced on the misspecified model is less than the variance increase due to including an extra parameter to estimate. Then, for some non-zero acceleration magnitudes and short integration times, the Doppler estimation using a misspecified model outperforms a correctly specified model in the MSE sense.

An evaluation of data processing when using the ActiGraph GT3X accelerometer in non-ambulant children and adolescents with cerebral palsy.

To evaluate vertical acceleration, vector magnitude, non-wear time, valid day classifications, and valid period classificationsin the data processing phase when using the ActiGraph GT3X accelerometer in non-ambulant children and adolescents with cerebral palsy (CP). Accelerometer data retrieved from 33 non-ambulant children and adolescents (4-17 years) with CPwere analysed. Comparisons of (i) vertical acceleration versus vector magnitude, (ii) two different non-wear times, (iii) three different settings to classify a day as valid and (iv) two different settings to classify a period as valid were made. Vector magnitude and a non-wear time of at least 90 consecutive minutes statistically significantly increased minutes recorded per day, especially for sedentary time. There was a statistically significant difference in numbers of valid days depending on time criteria set to determine a valid day, whereas there was no statistically significant difference in valid periods using 3 compared to 4 days. This study suggests using the pre-settings in ActiLife; vector magnitude, non-wear time of 90 consecutive minutes, 500 min recorded per day with periods of at least 3 valid days when assessing physical activity objectively by the ActiGraph GT3X accelerometer in non-ambulant children and adolescents with CP.

Driver behavior indices from large-scale fleet telematics data as surrogate safety measures

Large-scale telematics data enable a high-resolution inference of road network’s safety conditions and driver behavior. Although many researchers have investigated how to define meaningful safety surrogates and crash predictors from telematics, no comprehensive study analyzes the driver behavior derived from large-scale telematics data and relates them to crash data and the road networks in metropolitan cities. This study extracts driver behavior indices (e.g., speed, speed variation, hard braking rate, and hard acceleration rate) from large-scale telematics data, collected from 4000 vehicles in New York City five boroughs. These indices are compared to collision frequencies and collision rates at the street level. Moderate correlations were found between the safety surrogate measures and collision rates, summarized as follows: (i) When normalizing crash frequencies with traffic volume, using a traffic AADT model, safety-critical regions almost remain the same. (ii) The correlation magnitude of hard braking and hard acceleration varies by road types: hard braking clusters are more indicative of higher collision rates on highways, whereas hard acceleration is a stronger hazard indicator on non-highway urban roads. (iii) Locations with higher travel times coincide with locations of high crash incidence on non-highway roads. (iv) However, speeding on highways is indicative of collision risks. After establishing the spatial correlation between the driver behavior indices and crash data, two prototype safety metrics are proposed: speed corridor maps and hard braking and hard acceleration hot-spots. Overall, this paper shows that data-driven network screening enabled by telematics has great potential to advance our understanding of road safety assessment.

Visualization study on operating performance of a dual compensation chamber loop heat pipe under acceleration condition

In this article, a novel visual dual compensation chamber loop heat pipe (DCCLHP) under acceleration conditions was experimentally investigated. The working fluid was deionized water and the wick material was sintered nickel powder. Visual windows were installed on both compensation chambers (CCs) and condenser in order to observe the vapor and liquid distribution. The operating performance and physical mechanism of the proposed DCCLHP under both acceleration direction A and B at different heat loads and acceleration magnitudes were analysed in a systematic manner. Direction A refers the acceleration direction which was parallel to the axis of the evaporator and the CC without a bayonet placed at the outer edge of the rotating arm. While direction B is defined as the acceleration direction was perpendicular to the axis of the evaporator and the evaporator was placed at the outer edge of the rotating arm. In the current study, the heat load varies from 30 W to 130 W and the acceleration magnitude ranges from 1 g to 15 g. Experimental results revealed that: (i) The larger the heat load, the higher the operating temperature. Obviously waving of the vapor-liquid interface in the CC is observed at direction A. Bubbles generated in the CCs and the vapor-liquid interface moves back and forth in the condenser during temperature oscillation at both 70 W and 90 W for the case of 13 g and direction B. (ii) Under direction B, the DCCLHP presents lower operating temperature and higher thermal conductance. The maximum temperature is 143.2 °C at 5 g and 90 W under direction A. The maximum thermal conductance is 1.70 W/K at 13 g and 130 W under direction B. (iii) In general, the operating temperature shows a trend of decreasing first and then increasing with the increase of acceleration. Whereas the thermal conductance shows an opposite behavior. The transition acceleration, namely the acceleration magnitude at the minimum temperature, is 13 g for the case of direction A. However, under direction B, the large heat load can result in a large transition acceleration. (iv) Intermittent spattering of liquid drops is observed in the CCs at 70 W and 15 g under direction A. The flow pattern under direction A is different with that under direction B at each heat load. Multiple segments of the liquid and vapor phase alternately distribute and stratified flow forms in the condenser.

Optimal Circle-to-Ellipse Orbit Transfer for Sun-Facing E-Sail

The transfer between two coplanar Keplerian orbits of a spacecraft with a continuous-thrust propulsion system is a classical problem of astrodynamics, in which a numerical procedure is usually employed to find the transfer trajectory that optimizes (i.e., maximizes or minimizes) a given performance index such as, for example, the delivered payload mass, the propellant mass, the total flight time, or a suitable combination of them. In the last decade, this class of problem has been thoroughly analyzed in the context of heliocentric mission scenarios of a spacecraft equipped with an Electric Solar Wind Sail as primary propulsion system. The aim of this paper is to further extend the existing related literature by analyzing the optimal transfer of an Electric Solar Wind Sail-based spacecraft with a Sun-facing attitude, a particular configuration in which the sail nominal plane is perpendicular to the Sun-spacecraft (i.e., radial) direction, so that the propulsion system is able to produce its maximum propulsive acceleration magnitude. The problem consists in transferring the spacecraft, which initially traces a heliocentric circular orbit, into an elliptic coplanar orbit of given eccentricity with a minimum-time trajectory. Using a classical indirect approach for trajectory optimization, the paper shows that a simplified version of the optimal control problem can be obtained by enforcing the typical transfer constraints. The numerical simulations show that the proposed approach is able to quantify the transfer performance in a parametric and general form, with a simple and efficient algorithm.

Comparing tibial accelerations between delivery and follow-through foot strikes in cricket pace bowling

ABSTRACT Foot strikes of the pace-bowling delivery stride produce large ground reaction forces, which may be linked to injury, yet the biomechanics of the follow-through are unknown. This study assessed tibial accelerations across the delivery and follow-through foot strikes in pace bowlers and evaluated relationships between these measures and five common pace-bowling intensity metrics. Fifteen sub-elite male pace bowlers performed deliveries at warm-up, match, and maximal intensities. Tibial accelerations were measured using tibial-mounted inertial measurement units and recorded at back- and front-foot initial and re-contacts. A trunk-worn global navigation satellite system unit measured PlayerLoad™, run-up speed, and distance. Ball speed and perceived exertion measures were also recorded. A linear mixed model showed statistical significance of prescribed intensities (p < .001) and foot strike for tibial acceleration (p < .001). Tibial accelerations showed positive increases with changes in prescribed intensity (p < .05). The greatest magnitude of tibial acceleration was found at back foot re-contact (mean ± SD; 1139 ± 319 m/s2). Repeated-measures correlations of tibial acceleration between foot contacts were weak (r = 0.2–0.4). The greatest magnitude of tibial acceleration reported at back foot re-contact may have implications for injury incidence, representing an important avenue for future pace bowling research.

Numerical Study on Seismic Response of Offshore Wind Turbine Monopile in Multi-Layered Soil Profile of Arabian Sea

The seismic performance of monopiled offshore wind turbine (OWT) structures was evaluated numerically. The aim was to analyze offshore wind farm sites on complicated layered seabed with high seismicity. Following pile soil analysis (PISA) model, three-dimensional (3D) numerical evaluations were undertaken for two separate locations under two independent seismic events. The effects of pile diameter, depth, site impact owing to transverse soil layering, uni-directional and multi-directional seismic loading and seismic acceleration magnitude are presented. Dynamic impedance depth variation and site response analysis via lateral displacement, lateral soil response and Fourier response amplitude are explored in frequency and time domain. In a seismic zone with stratified soil, pile diameter has a greater influence. Variations in soil profile affect wind turbine performance and seismic sensitivity. This research will give a strong platform for later studies to recommend a safe wind farm site based on simulation results.

The effects of visual context on visual-vestibular mismatch revealed by electrodermal and postural response measures

BackgroundNo objective criteria exist for diagnosis and treatment of visual-vestibular mismatch (VVM).ObjectiveTo determine whether measures of electrodermal activity (EDA) and trunk acceleration will identify VVM when exposed to visual-vestibular conflict.MethodsA modified VVM questionnaire identified the presence of VVM (+ VVM) in 13 of 23 young adults (34 ± 8 years) diagnosed with vestibular migraine. Rod and frame tests and outcome measures for dizziness and mobility were administered. Participants stood on foam while viewing two immersive virtual environments. Trunk acceleration in three planes and electrodermal activity (EDA) were assessed with wearable sensors. Linear mixed effect (LME) models were used to examine magnitude and smoothness of trunk acceleration and tonic and phasic EDA. Welch’s t-test and associations between measures were assessed with a Pearson Correlation Coefficient. Effect sizes of group mean differences were calculated.ResultsGreater than 80% of all participants were visually dependent. Outcome measures were significantly poorer in the + VVM group: tonic EDA was lower (p < 0.001) and phasic EDA higher (p < 0.001). Postural accelerations varied across groups; LME models indicated a relationship between visual context, postural, and ANS responses in the + VVM group.ConclusionsLower tonic EDA with + VVM suggests canal-otolith dysfunction. The positive association between vertical acceleration, tonic EDA, and visual dependence suggests that increased vertical segmental adjustments are used to compensate. Visual context of the spatial environment emerged as an important control variable when testing or treating VVM.

Effect of Heat Treatment on the Vibration Isolation Performance of Axially Symmetric NiTi Wire Mesh Damper

In this paper, superelastic (SE) NiTi wire is used to fabricate axially symmetric wire mesh dampers (WMDs) with the expectation of a higher damping capacity. However, the phase transformation damping of the NiTi WMD could be suppressed by the cold-work-induced dislocation. Therefore, the NiTi WMDs were heat-treated and then tested by a hydraulic universal testing machine. The NiTi WMD is found to achieve higher damping capacity when heat-treated at 200 °C. However, the WMD heat-treated at 250 °C suffers from a sharp decline in the loss factor in exchange for an improvement in the stiffness. The sine sweep test was then conducted to examine the dependency of the WMD’s vibration isolation performance upon the heat treatment temperature and the excitation acceleration. The NiTi WMD outperforms the 304 stainless steel (SS 304) WMD in damping capacity only when the excitation acceleration magnitude is less than 1.5 g. The stiffness of NiTi WMD can be improved without significantly compromising its damping capacity by heat treatment at 200 °C for 30 min. The present work carries out comprehensive measurements of the NiTi WMD’s response to dynamic mechanical test and sine sweep test and addresses how heat treatment influences the stiffness and damping capacity of the SE NiTi WMD.

Verification of Usability of the Hybrid III Dummy for Crash Tests - Pilot Experiment

The study is focused on the dynamic response of the head and thoracic area of an anthropomorphic test device (ATD) during low-impact collisions with a tram. Two collision scenarios were analyzed: the frontal impact (a chest as a primary contact area) and the side impact (a thigh as a primary contact area). The measurements used a pedestrian dummy (Hybrid III 50th percentile male dummy, Jasti Co., ltd., Tokyo, Japan) and a unique pendulum impact testing machine (impactor) of own design. The crash tests were conducted at various impact intensities (velocities) into the chest and left thigh of the dummy. The primary outcome variable was a resultant magnitude of acceleration measured in the area of thoracic vertebra Th5 and on the vertex of the head. The differences between both areas of interest were analyzed as well. The results provide the analysis of the dynamic behavior of the head and chest of the dummy at low impacts, the validation of the impactor for crash-test analyses, and a possible way to verify the use of the dummy in similar experimental settings.