Location Of Impact Point Research Articles

Impact localization of composite laminates based on weight function compensation localization algorithm of thin film sensors

ABSTRACT Composite structures are sensitive to impact damage in practical engineering. Electric resistance change method (ERCM) is an ideal technique for damage monitoring of composite structures. Due to the anisotropy of fiber-resin matrix composites, impact location monitoring is difficult, and research on impact location of fiber composite laminates (FRPs) is limited. A preparation method of MXene/CNT/CuNps thin film sensor is proposed. According to the modeling simulation and theoretical calculation, the resistance change characteristics of the thin film sensor are obtained, the relationship between the impact distance and the resistance change is established, and the sensor array is designed. A three-point localization algorithm and a weight function compensation localization algorithm are proposed, which can improve the imaging accuracy of the impact position. The impact point location was observed and analyzed using ultrasonic C-scan technology. The results show that the weight function compensation positioning algorithm can accurately locate the impact of the composite structure, and the error in the X direction is 7.1%, the error in the Y direction is 0.03%, which verifies the effectiveness of the method.

Experiment and Simulation Study on the Dynamic Response of RC Slab under Impact Loading

Reinforced concrete (RC) slab is an important component in civil construction and protection engineering, and its dynamic response under impact loading is a complex mechanical problem, especially for two or multiple continuous impact loads. In this paper, a series of drop hammer impact tests were carried out to investigate the dynamic response of RC slabs with two successive impacts. The time history of impact force and the failure characteristic of the slab surface were recorded. Moreover, four influence factors, including slab thickness, reinforcement ratio, impact location, and drop hammer height have been discussed. Besides, a 3D numerical model based on the finite element method (FEM) was established to expand the research of constrained force, deflection, and vertical stress of an RC slab. The results show that increasing the slab thickness and reinforcement ratio can improve the impact resistance of an RC slab. The impact point location and drop hammer height have a great influence on the dynamic response of the RC slab. In addition, the RC slab will have more obvious damage under the second impact, but the dynamic response becomes weaker. It may be because of the local damage in the concrete caused by the first impact that would weaken the propagation of vibration.

Dynamic response analysis of blocks-combined dam under impact load

In order to reduce the damage of ordinary gravity dam impacted by boulders in debris flow, a blocks-combined dam based practical project is proposed. The dynamic response of the proposed dam under impact load is investigated by using ABAQUS finite element software. Considering the impact velocity and impact height, the anti-impact performance of blocks-combined dam is discussed in terms of deformation, displacement, impact force, acceleration, and energy, and is compared with that of ordinary dam. Results show that the displacement, impact force and acceleration of dam increase with the increase of impact velocity and height. The impact energy of blocks-combined dam is mainly absorbed and consumed by the friction between the component interfaces, which is related to the location of impact point. Compared with the ordinary gravity dam, the blocks-combined dam has better impact resistance to boulders in debris flow.

A Study of Impact Point Detecting Method Based on Seismic Signal

The projectile landing position has to be determined for its recovery and range in the targeting test. In this paper, a global search method based on the velocity variance is proposed. In order to verify the applicability of this method, simulation analysis within the scope of four million square meters has been conducted in the same array structure of the commonly used linear positioning method, and MATLAB was used to compare and analyze the two methods. The compared simulation results show that the global search method based on the speed of variance has high positioning accuracy and stability, which can meet the needs of impact point location.

Vibro-Shock Dynamics Analysis of a Tandem Low Frequency Resonator-High Frequency Piezoelectric Energy Harvester.

Frequency up-conversion is a promising technique for energy harvesting in low frequency environments. In this approach, abundantly available environmental motion energy is absorbed by a Low Frequency Resonator (LFR) which transfers it to a high frequency Piezoelectric Vibration Energy Harvester (PVEH) via impact or magnetic coupling. As a result, a decaying alternating output signal is produced, that can later be collected using a battery or be transferred directly to the electric load. The paper reports an impact-coupled frequency up-converting tandem setup with different LFR to PVEH natural frequency ratios and varying contact point location along the length of the harvester. RMS power output of different frequency up-converting tandems with optimal resistive values was found from the transient analysis revealing a strong relation between power output and LFR-PVEH natural frequency ratio as well as impact point location. Simulations revealed that higher power output is obtained from a higher natural frequency ratio between LFR and PVEH, an increase of power output by one order of magnitude for a doubled natural frequency ratio and up to 150% difference in power output from different impact point locations. The theoretical results were experimentally verified.

Experimental study of compression after impact of asymmetrically tapered composite laminate

This paper presents an experimental study of CAI (compression after impact) of tapered composite laminate. Two types of layup with thickness changing from 4mm to 6mm are considered. A new CAI testing rig, suitable for the specimens and a brief description of impact damage are presented first. Then, the behavior of impacted specimens under compressive loading is discussed along with the effects of ply drop-off parameters (taper angle, ply drop-off disposition and configuration) and impact point location on the failure mechanism. Finally, the residual strength in CAI of tapered laminates is compared with equivalent flat laminates. The results show that compressive behavior of the specimens is mostly governed by a coupling between compression and bending, generated by the discontinuity of the neutral axis in the tapered region. Despite this difference of behavior with flat laminates, the presence of ply drop-off has little effect on the residual strength in CAI.

Vibrotactile Representation of Mobile Robot Collisions Using Differences in Stimulus Duration

Collisions of a mobile robot with unnoticed objects degrade the operator’s experience and threaten the success of an exploratory mission. We investigated the effects that manipulating the duration of vibrotactile stimuli on both hands has on the perceived impact location. We used 400 Hz sine waves whose amplitude were modulated by a constant sustain phase and an decaying exponential release phase. To control the stimulus duration, we manipulated the length of the sustain phase and the damping coefficient of the release phase. The results of a preliminary psychophysical experiment suggest that differences under 20 ms influence the perception of the impact point location.

NUMERICAL ANALYSES OF CERAMIC/METAL BALLISTIC PANELS SUBJECTED TO PROJECTILE IMPACT

The paper concerns research and development on modern, ceramic-based, protective layers used in the armour of tanks, combat vehicles and aeroplanes. A task of ceramic panels is reduction and dispersion of localized kinetic energy before a projectile or its fragment approaches the interior of protected object. The numerical investigations have been performed to determine the ballistic resistance of ceramic/metal panels subjected to projectile impact. The impact of the 7.62mm armour-piercing projectile on the ceramic elements backed by a metal plate was analyzed. The tested panels were composed of a ceramic layer (Al 2O3, SiC or B4C) and a metal layer (7017 aluminium alloy, Armox 500T steel or Ti6Al-4 titanium alloy). Different shapes of ceramic elements were analyzed, including hemispheres and pyramids, with respect to standard flat tiles. The influence of the impact point location was also taken into considerations. The computer simulations were performed with the Finite Element Method implemented in LS-DYNA code. Full 3D models of the projectile and targets were developed with strain rate and temperature dependent material constitutive relations. The conclusions presented in the paper can be applied to develop modern impact protection panels in which the appropriate balance between the mass and protection level must be accomplished.

Interaction of 30 keV O3+ ions with Al2O3 nanocapillaries

Interaction of 30keV O3+ ions with capillaries in an Al2O3 membrane was studied. The charge state distribution and the angular distribution of the ions transmitted through the capillaries were measured. Shifts of the transmission profile centroid by twice of the capillary tilt angle ψ and double-peak structure in the transmission profile were found. Difficulties exist in determination of the impact point location on the capillary wall and the scattering angle for each collision to interpret the observed 2ψ shift phenomenon. The transmission profile width and ion guiding ability of the concerned capillaries for the used projectile ions were analyzed. Comparison of the present guiding angle and the prediction of scaling laws was conducted. Further work concerning the influence of the material and its surface treatment on the guiding properties is needed.

FORENSIC INJURY BIOMECHANICS METHODOLOGIES APPLIED TO TRAFFIC ACCIDENT RECONSTRUCTION

Every year about 1.2 million persons die and more than 50 million are injured in road accidents. Reconstruction of traffic accident plays an important role for the investigation of the causes of such events. Nowadays modern computational techniques can be applied for the determination of the dynamic conditions of the accident, such as the the speed or the maneuvers. Forensic injury biomechanics is a current topic of research (Hayes 2007, Freeman 2010, Guo, 2008, Motherway, 2009) and can be applied successfully especially for the reconstruction of accidents involving vulnerable road users (or vehicle occupants not using the retention systems such as the seat belt or even motorcyclists not using the helmet. Since there is a direct effect between the use of safety systems and injuries, the development and use of anthropomorphic computational dummies plays and important role to the answer to some legal forensic questions related with not only the dynamics of the accident but also about the use of the retention systems. The correlation between injuries and biomechanical criteria is crucial to the determination of the causes of some accidents such as pedestrian impacts where the speed of the vehicle and the impact point location can be determined from the injuries. Such computational models are under development and forensic biomechanics is an area where knowledge from engineering and medicine should be interconnected. In addition, commercial software for accident reconstruction PC-Crash (Figure 1) is used for real world accident where the presented methodologies are applied. The characterization of the level and typical location of injuries sustained by the victims allows, on one hand, to perform a more accurate reconstruction of the accident. Also the importance of parameters such as speed, which depends on the impact’s severity, as well as the use of helmet, are related with the injuries illustrating the importance of such methodologies that correlates accident dynamics with injuries, that is very important because usually drivers lie about the speed and impact points and fatal victims cannot give their statement. Figure 1: Accident reconstitution Scenario and