Car Front Research Articles

구조 진동 측정을 이용한 프레스 성형품 넥 결함 검사기술 타당성 연구

If defects occur in a press-formed article, the mechanical properties change and the vibration characteristics may change. In particular, it is not difficult to prove a crack defect on the basis of structural vibration measurement. The purpose of this study was to develop a defect inspection technique that can quickly determine whether the neck of a press-formed article is defective by measuring the simple structural vibration of the neck, which indicates a defect of a fine press-molded product, rather than a crack. The press moldings used in the experiment were automobile front door panels; the structural vibration of the front door panels was measured with an impact hammer test. The frequency response function measured by the impact hammer test was obtained by the vibration frequency analysis program LMS Test.lab. With this method, we compared and analyzed whether there is a significant difference from a front door panel in which a defect is generated, on the basis of the natural frequency dispersion that many normal front door panels without defects have in the corresponding mode. A total of 10 normal front door panels and two necked defective front door panels were tested. The observable mode frequencies of the normal front door panel and the necked front door panel were shown in terms of sigma levels to determine if there is a significant natural frequency difference. In addition, normal door panels without necks were divided into two groups with a difference of approximately 9 months in production. SPSS software was used for the statistical validation t-test. From this experiment, the results will become the basic data of a test method to detect the defective necks of press-formed parts through natural frequency measurement.

Investigation of Forced Frequency in a Commercial Vehicle Suspension System

Abstract Vehicle suspension plays a vital role in maintaining the center of gravity to achieve perfect balancing of the vehicle to provide the comfortable ride. While designing the suspension system of automobile, vibration is the main aspect to be considered. This paper aims to analyze the automobile front and rear suspension for a four wheeler using analytical and numerical approach. Existing details of the suspension is collected using the concept of reverse engineering. Natural and forced frequency of the front and rear suspension system is calculated theoretically based on the collected data's. The natural frequency and forced frequency is numerically computed for front and rear suspension. The amplitude of vibration is reduced by replacing the spring material and its forced frequency is reduced by 1.18 % and 1.56 % for front and rear suspension system respectively. This result reveals that low carbon steel has ability to reduce the forcing frequency and can produce comfort ride.

Dynamic reliability analysis model for structure with both random and interval uncertainties

Aiming at analyzing the safety of the dynamic structure involving both input random variables and the interval ones, a new dynamic reliability analysis model is presented by constructing a second level limit state function. Two steps are involved in the construction of the dynamic reliability model. In the first step, the non-probabilistic reliability index is firstly extended to the dynamic structure, in which the uncertainties of interval inputs can be analyzed by fixing random inputs and time parameter. In the second step, the second level limit state function is constructed by considering the fact that the non-probabilistic reliability index larger than one corresponds to the safe state, in which the uncertainties of random inputs are taken into account. Generally, the actual reliability of dynamic structure with both random and interval inputs is an interval variable, and theoretic analysis illustrates that the proposed reliability is equivalent to the lower bound of the actual reliability, which can provide an efficient way for measuring the safety of dynamic structure. For estimating the proposed reliability, a double-loop optimization algorithm combined with Monte Carlo Simulation as well as the active learning Kriging method is established. Several examples involving a cylindrical pressure vessel, an automobile front axle and a planar 10-bar structure are introduced to illustrate the validity and significance of the established reliability model and the efficiency and accuracy of the proposed solving procedure.

Simulation and Optimization of Multi-step Stamping Forming Process for Car Front Panel

Simulation and Optimization of Multi-step Stamping Forming Process for Car Front Panel

ANALYSIS OF DALLARA T12 RACE CAR FRONT WING VIBRATIONS

This work investigates aerodynamic elements’ vibrations of high-speed vehicles on the example of the Dallara T12 race car front wing. Made up energy spectrums of wing vibrations for three specific cases arising during driving on the circuit.

Flow-induced vibration analysis of a vehicle's front side window glass

This study analyses the flow-induced vibration of a car's front side window glass. The following working steps were carried out: experimental modal analysis to yield the dynamic characteristics of the system; wind tunnel experiments and corresponding numerical simulations with a computational fluid dynamics (CFD) code to acquire the pressure field including the fluctuations on the side glass; and a MATLAB implementation of the vibration velocity response calculated with the Corcos model and Mellen elliptical model. The MATLAB model calculates the averaged vibration velocity response by means of the pressure loading from the wind tunnel test or from the CFD simulations as well as by means of the result of the experimental modal analysis. The hereby calculated vibration response of the side glass has been validated by the results of laser Doppler vibrometer measurements in the wind tunnel. Through parameter study with the MATLAB algorithm, it was found that flow convective velocity with U c = 0.6*U, flow decay rates with α x = 0.1 and α z = 0.77 could be considered as the suitable values for the structure vibration velocity response calculation in this type of flow with a low Mach number.

Adaptive Light Control Berbasis Kendali Fuzzy

Standard headlights will shine with a fixed intensity even though the environmental light changes. High-intensity lights sometimes make other drivers glare and potentially cause accidents. Adaptive Light Control (ALC) is a car headlights control system that can automatically adjust the intensity of the lamp according to the intensity of the light environment. In this research, we developed ALC which was able to regulate the intensity of the lamp according to the intensity of the environmental light including the light of the car in front. Light settings are performed using a fuzzy control system by utilising environmental light intensity and the distance of the car to the object as input. The developed ALC system was tested on remote control cars equipped with sensors and microcontrollers. The intensity of headlight begins to fade on the distance of the car to the object of 92 cm for objects in front of, 108 cm for objects on the left, and 22 cm for objects on the right.

Vision-Based Parking Entry Control System

Vision-based control systems are very promising in the Intelligent Transportation System (ITS). This paper proposes a system that use the vision system to control vehicle entry at the bridge gate at a certain facility. The system detects the presence of the car and captures the front car image to proceed to plate recognition process. Vehicle plate region is extracted using the size filtering, image thresholding and object counting algorithms. Optical character recognition technique is used in the recognition module. The result from the recognition module is then compared to the record in the database for information like the vehicle owner name, type of car, etc. The overall system is implemented and simulated in LabVIEW and the performance of recognition is tested on the real image. The system can successfully detect and recognize the plate number with minimum error.

Measuring the absolute distance of a front vehicle from an in-car camera based on monocular vision and instance segmentation

The requirements of distance measurement have increased with the development of auto vehicle driving. Traditional methods for distance estimation require the complex calibration from intrinsic and external parameters of the camera. Recent methods based on the neural network structure mainly measure the relative depth of whole images. We adopt monocular vision with instance segmentation and camera focal length to detect the absolute distance of front cars from in-car cameras. First, we extract the location of the cars from the object detection network. Second, the location of cars is sent to the vehicle classification network and instance segmentation network to obtain the type of the cars and their mask value. Here, we use a model trained by the CompCars dataset to classify car types, and we train a new instance segmentation model using the Cityscapes dataset to obtain each car’s mask. Third, in accordance with the camera imaging principle, the absolute distance of cars in the images is calculated based on the relationship between the size information of different car types and their mask values. The proposed method is examined with the KITTI dataset, and the experiment shows that its results can be close to the ground truth. Moreover, the proposed method uses the instance segmentation network to reduce complexity of the depth estimation process and it can still generate satisfactory results even when cars are partly occluded.

Computer-aided Prediction of Airborne Sound Transmission through the Front Car End

Computer-aided Prediction of Airborne Sound Transmission through the Front Car End

Optimization of Baja Racing Car Front Suspension Parameters Based on ADAMS

In order to make the Baja racing car with better maneuvering stability, the ADAMS/Car module is used to build the front suspension structural model of the Baja racing car. Through the model simulation test, the influence of each positioning parameters of the suspension on the performance of the Baja racing car suspension is analyzed. The obtained results gradually optimize the position of each hard point. By optimizing each positioning parameter, the overall performance of the suspension is significantly improved, so that the racing car has good handling and stability. The method described in this article makes suspension optimization faster and more accurate.

Impact of Longitudinal Train Dynamics on Train Operations: A Simulation-Based Study

The paper is an attempt to evaluate the impact of coupler forces in the train produced during braking. The braking signal generated from a locomotive control valve takes a few milliseconds to reach the adjoining car in coupled passenger trains. The brake comes into effect in the last car of the train after a few seconds due to the time lag. This delayed application of brakes results in pushing off the rear cars into the front cars, producing large compressive forces in the coupler. These compressive forces, mainly longitudinal in nature cause passenger discomfort and poor ride quality. Non-linear dynamic analysis has been conducted to represent the characteristic of coupling forces between the coaches in longitudinal train dynamics. The analysis involved the mathematical model of coupler force and braking force through experimental results. In addition, effects of various braking phases, i.e., auxiliary, service and emergency braking on the in-train forces, were also investigated using ‘universal mechanism—software of dynamics of mechanical systems’. The train response due to different braking phases on the train longitudinal dynamics is thoroughly studied using multibody dynamics analysis. The results establish that the in-train forces were well within the limits prescribed by Research Design and Standard Organisation. The maximum compression force increased when the forward velocity of the train is reduced during the braking phase. And, this maximum compression occurs at the third quarter of the train.

Dynamic performance of high-speed train passing windbreak breach under unsteady crosswind

ABSTRACTField test and computational fluid dynamics (CFD) method are conducted to investigate the safety of high-speed train under unsteady crosswind. Wheel–rail forces of high-speed train passing a breach between two windbreaks under strong crosswind are measured in a field test. The derailment coefficient of first wheelset of front car at the windward side reaches the allowable value. Meanwhile, the left and right of lateral wheel–rail force are in the opposite direction. This kind of phenomenon has not been tested before. Therefore, CFD and multi-body simulations are performed in order to study the phenomena. Good agreement is obtained between the simulation results and the experimental data. It is concluded that the sudden increase of transient aerodynamic loads, when the train passing the breach, is the root of this phenomenon; after running along the same direction as carbody and bogie run along the opposite direction during the high-speed train passing the windbreak breach; larger opposite longitudinal creeping forces of first wheelset compel the first wheelset to yaw toward the windward side; meanwhile, larger lateral wheel–rail forces compel the first wheelset to run toward the windward side rail; the left and right lateral wheel–rail forces become opposite because the right wheel impacts the windward side rail.

Optimization of Baja Racing Car Front Suspension Parameters Based on ADAMS

Optimization of Baja Racing Car Front Suspension Parameters Based on ADAMS

Risky behaviors of taxi drivers in Bandar Abbas, Iran.

Background and aimIt has been revealed that taxi drivers break more traffic rules than ordinary drivers. Such risky behaviors include stopping at prohibited areas and sudden change of direction. The present study aimed to determine the Risky Behaviors of Taxi Drivers in Bandar Abbas, IranMethodsIn this cross-sectional study, 184 taxi drivers were randomly selected from eight taxi stations located at different parts of Bandar Abbas city in 2016. Taxi drivers’ risky behaviors were evaluated via a 20-item questionnaire. Data were analyzed by SPSS version 19, using descriptive statistics and independent-samples t-test. The p-values less than 0.05 were considered as statistically significant.ResultsThe mean age of the drivers was 45.1 (±11.1) years. The mean of their occupational experience was 18.7 (±10.8) years. The risky behaviors which showed the highest frequency were respectively, failure to use signal-lights, driving too close to the cars in front, refusing to drive within the lanes and erratic lane changing.The lowest frequency belonged to running a red light, ignoring ‘no entry’ signs and taking illegal U-turns. Risky driving behaviors were shown to be significantly more prevalent among drivers with previous experience of crashes or tickets than drivers with no such experiences (p<0.01).ConclusionIncreasing the role of police supervision for the strict implementation of driving laws, and modification of the drivers’ behavior and implementation of periodic training programs on drivers’ safety issues can be considered for reducing taxi drivers’ unsafe behaviors.

Effect of distraction task on driving performance of experienced taxi drivers

Abstract Background Driving performance is influenced by human, vehicular, and environmental factors. Objectives To investigate the effects of distraction tasks, such as sending a text message (STM) and searching a navigation device (SN), on the driving performance of experienced taxi drivers. Methods Twelve male taxi drivers (age: 56.3 ± 4.4 y; experience: 28.4 ± 6.4 y) and 14 female taxi drivers (age: 55.5 ± 3.5 y; experience: 19.4 ± 5.0 y) drove in a simulator at a constant speed (90 km/h) for 2 min while maintaining a gap of 30 m from the car in front, also traveling at 90 km/h. Participants were instructed to drive only for the first 1 min (control phase). For an additional 1 min (task phase), they were instructed to drive only, drive + STM, or drive + SN. Results Compared with driving only, during driving + STM or driving + SN, the drivers’ skin conductance level was relatively increased, suggesting that the distraction task increased the drivers’ workload and sympathetic nervous system activity. Compared with driving only, during driving + STM or driving + SN, the average distance from the car in front, speed deviation, and anterior–posterior and medial–lateral coefficients of variation increased, suggesting that maintaining the instructed gap and speed, and the longitudinal and transverse control of the car, was more difficult because of the distraction task. Conclusions Even for highly experienced taxi drivers, distraction tasks increased workload, increased the difficulty of vehicle control, and detracted from safe driving.

Have pedestrian subsystem tests improved passenger car front shape?

Subsystem impactor tests are the main approaches for evaluation of safety performance of vehicle front design for pedestrian protection in legislative regulations. However, the main aspects of vehicle safety for pedestrians are shape and stiffness, and though it is clear that subsystem impact tests encourage lower vehicle front stiffness, it is unclear whether they promote improved vehicle front shapes for pedestrian protection. The purpose of this paper is therefore to investigate the effects of European pedestrian safety regulations on passenger car front shape and pedestrian injury risk using recent German In-Depth Accident Study (GIDAS) pedestrian collision data and numerical simulations. Firstly, a sample of 579 pedestrian collision cases involving 190 different car models between 2000–2015 extracted from the GIDAS was used to compare front-end shapes of passenger cars manufactured before and after the legislative pedestrian safety regulations were introduced in Europe. The focus was on changes in passenger car front shape and differences in pedestrian AIS2+ (Abbreviated Injury Scale at least level 2) leg, pelvis/femur and head injury risk observed in collisions. Multi-body simulations were also used to assess changes in vehicle aggressivity due to the observed changes in vehicle shape. The results show that newer passenger cars tend to have a flatter and wider bumper, higher bonnet leading edge, shorter and steeper bonnet and a shallower windscreen. Both the collision data and the numerical simulations indicate that newer passenger car front bumper designs are significantly safer for pedestrians’ legs. However, the results also show that the higher bonnet leading edge in newer passenger cars is poor for pedestrian pelvis/femur protection, even though newer cars show an obviously lower AIS2+ injury risk to younger pedestrians in collisions. Newer cars have a lower AIS2+ head injury risk for pedestrians in collisions, but the numerical analysis indicate that this is not likely due to shape changes in passenger car fronts. Overall, the introduction of pedestrian safety regulations has resulted in reductions in pedestrian injury risk, but further benefits would accrue from tests which promote a lower bonnet leading edge. The influence of vehicle shape on pedestrian head injury risk remains unclear.

Engineering Design of Safe Automobile Front Strut Tower Brace with Predetermined Destruction

This paper shows the developed design of an automobile front strut tower brace instantly breakable on reaching a predetermined value impact load, which allows the impact load not to be transferred to the opposite strut. An automobile front strut tower brace with the directed destruction V-shaped element using the SolidWorks and SolidWorks Simulations software complex was developed, designed and analyzed. The obtained data were confirmed experimentally. By changing geometric features of the V-shaped element, it is possible to change the impact load value required for its destruction.

Hardware Simulation of Advanced Driver Assistance Systems Based on Fuzzy Logic

Advanced Driver Assistance Systems (ADAS) is a system that has the function of helping the driver to be safe the trip without reducing the convenience. The subsystems developed in ADAS among other Automatic Braking System (ABS) which functions to make braking decisions when there is an object in front of it, Rear-end Collision Avoidance System (RCAS) that serves to avoid rear-end collision, Active Lane Keeping Assist (ALKA) which serves to keep the vehicle from getting off lane from its proper lane, and Adaptive Cruise Control (ACC) which serves to adjust the distance of the car with another car in front. This paper discusses the development of fuzzy logic based algorithms for those subsystems. The developed algorithm test was conducted using experimental car. The test results on the three variations of speed: slow-speed, medium-speed, and high-speed shows that the algorithm developed of ABS, RCAS, ALKA, and ACC can work according to design.

Dynamic energy absorption of ultrafine-grained TWIP steel under axial impact loading

This research focuses on studying the dynamic energy absorption property of a micro-alloyed TWIP steel, which was proposed to act as a connection part between car front bumper and chassis in middle-class cars for vehicle safety. The studied TWIP steel was designed based on stacking fault energy of 25mJ/m2. The as-cast steel was deformed in hot and cold rolling to 2 mm thick sheets. Subsequently, recrystallization annealing was applied to the heavily cold-worked steel at different temperatures to obtain different ultrafine grain structures. The mechanical properties were determined using tensile tests. It was observed that at 900°C, the optimal temperature for strengthening by vanadium carbide precipitation, it was too low to complete recrystallization. However, at 1000°C, an ultrafine-grained structure was formed with high yield, tensile strengths and elongation of about 700MPa, 1100MPa and 30% respectively. Accordingly, TWIP steel was used for crash analysis simulation using ANSYS Workbench R14.5. Thin-walled square columns of that steel were employed for energy absorbance during a collision regarding progressive plastic deformation. The crashworthiness criteria were studied under different impact conditions with thicknesses of 0.25, 0.5, 0.75 and 1 mm. Simulation results showed high initial peak force during the impact. Hence, a trigger mechanism of an external tapered plunger was proposed to reduce it. This combination of new material and innovative design promises enhancement car safety.