Car Underbody Research Articles

Lexicon-based Sentiment Analysis for Product Design and Development

This paper discusses the role of text mining and sentiment analysis in collecting and analyzing customers’ verbatim/voice of the customer for product design and development. In the illustration case of designing car underbody, the data were collected from a car online forum discussion website and processed using text mining techniques with “underbody” as a keyword. The result of the analysis finds there are worries regarding underbody durability against rust and damages. This finding is used as a reference point for the car underbody design process.

Enhancement in Quality Estimation of Resistance Spot Welding Using Vision System and Fuzzy Support Vector Machine

The current nondestructive testing methods such as ultrasonic, magnetic, or eddy current signals, and even the existing image processing methods, present certain challenges and show a lack of flexibility in building an effective and real-time quality estimation system of the resistance spot welding (RSW). This paper provides a significant improvement in the theory and practices for designing a robotized inspection station for RSW at the car manufacturing plants using image processing and fuzzy support vector machine (FSVM). The weld nuggets’ positions on each of the used car underbody models are detected mathematically. Then, to collect perfect pictures of the weld nuggets on each of these models, the required end-effector path is planned in real-time by establishing the Denavit-Hartenberg (D-H) model and solving the forward and inverse kinematics models of the used six-degrees of freedom (6-DOF) robotic arm. After that, the most frequent resistance spot-welding failure modes are reviewed. Improved image processing methods are employed to extract new features from the elliptical-shaped weld nugget’s surface and obtain a three-dimensional (3D) reconstruction model of the weld’s surface. The extracted artificial data of thousands of samples of the weld nuggets are divided into three groups. Then, the FSVM learning algorithm is formed by applying the fuzzy membership functions to each group. The improved image processing with the proposed FSVM method shows good performance in classifying the failure modes and dealing with the image noise. The experimental results show that the improvement of comprehensive automatic real-time quality evaluation of RSW surfaces is meaningful: the quality estimation could be processed within 0.5 s in very high accuracy.

A Novel Method of Using Vision System and Fuzzy Logic for Quality Estimation of Resistance Spot Welding

Finding a reliable quality inspection system of resistance spot welding (RSW) has become a very important issue in the automobile industry. In this study, improvement in the quality estimation of the weld nugget’s surface on the car underbody is introduced using image processing methods and training a fuzzy inference system. Image segmentation, mathematical morphology (dilation and erosion), flood fill operation, least-squares fitting curve and some other new techniques such as location and value based selection of pixels are used to extract new geometrical characteristics from the weld nugget’s surface such as size and location, shape, and the numbers and areas of all side expulsions, peaks and troughs inside and outside the fusion zone. Topography of the weld nugget’s surface is created and shown as a 3D model based on the extracted geometrical characteristics from each spot. Extracted data is used to define input fuzzy functions for training a fuzzy logic inference system. Fuzzy logic rules are adopted based on knowledge database. The experiments are conducted on a 6 degree of freedom (DOF) robotic arm with a charge-coupled device (CCD) camera to collect pictures of various RSW locations on car underbodies. The results conclude that the estimation of the 3D model of the weld’s surface and weld’s quality can reach higher accuracy based on our proposed methods.

Numerical investigation for the influence of the car underbody on aerodynamic force and flow structure evolution in crosswind

To investigate the aerodynamic behavior of underbody structure in crosswind conditions, two numerical simulation models have been developed by using computational fluid dynamics method. First, to validate the accuracy of these models, the wind tunnel experiment of model with simplified flat underbody has been designed. The computationally predicted results of realizable k-e model show consistency with experimental data, and the correlation deviation of aerodynamic force is less than 10%. By using such model, the aerodynamic force and flow field of car under steady crosswind are simulated using underbody structure, and the influence on the aerodynamic characteristic has been analyzed. It can be found that the aerodynamic force increased significantly under different yaw angle. The physical mechanism response has been clearly shown by investigating the flow field around car body by vortices visualization technique. The results of this study can be served as a suggestion for studying the vehicle stability of high-speed under crosswind.

Design and Aerodynamic Assessment of Diffuser with Longitudinal Separators for Underbody of Sedan

The aerodynamic characteristics have a great influence on the steering stability and the fuel economics of a high speed vehicle. The diffuser located at the aft part of a car underbody is one of the most important aerodynamic add-on devices. The parameters of the diffuser, including the diffuser angle, the number and the relative position of longitudinal separator (LS), the shape of the end plate and etc, will affect the underbody flow and the wake. Here, diffuser with longitudinal separator of different number and relative position was investigated. Numerical simulation was used to study the aerodynamic characteristics of a simplified sedan with different diffuser of longitudinal separator. The study found aerodynamic coefficient of the car changes little when we change the relative position of diffuser's longitudinal separator. Besides, we also found that increasing the number of the diffuser's longitudinal separator will increase the vehicle's aerodynamic drag coefficient and reduce the vehicle's lift coefficient.

Fluid motion for car undertrays in ground effect.

Air motion representative of some of the flows past a moving car is studied, particularly in the gap between the car underbody (undertray, front flap or forewing) and the ground, using theory and computation. The ground-affected flows encountered are two- or three-dimensional, laminar, transitional or turbulent, and attached or separated. Given Reynolds numbers in the approximate range 1–10 million, emphasis here is placed first on key physical flow mechanisms: viscous-inviscid interaction filling either much or part of the gap; the generation of strong upstream influence; an abrupt pressure jump at the leading edge; the moving-ground condition; substantial diffuser flow reversals and wake effects; in three dimensions the distinguishing between inflow and outflow edges; and turbulent flow modelling. Second, for various underbody shapes, predictions are presented of the surface pressures and shear stresses, the lift or downforce, and the velocity profiles. Extensions of these to include edge effects, three-dimensionality and turbulence modelling are examined, along with optimization for certain shapes concerned with front-flap design and comparisons with recent experiments.

Acoustic modeling of road vehicles for traffic noise prediction: Determination of the sources heights

For traffic noise predictions road vehicles can be modeled by point sources. When dealing with the evaluation of noise barrier’s efficiency or of far-field noise, the knowledge of the sources heights is of primary importance. Their determination can be obtained from two different methods. The first one deals with an inverse fitting procedure performed on experimental excess attenuation results between two receivers 7.50 m apart. Knowing the noise frequency spectrum at the reference microphone and the pavement and close ground impedances, it becomes possible to adjust the source height by minimizing the prediction/measurement difference. By this procedure, the equivalent noise source is found very close to the surface. Otherwise, sources heights can be obtained directly using microphone arrays. These measuring techniques are now commonly used to localize sound sources of railway vehicles. Their application to road vehicles appears to be more recent. For the present case dealing with the determination of the source height only, a simple vertical array can be implemented. Preliminary measurements made on a light vehicle confirm that the acoustic radiation due to the various sources (including engine noise) comes practically entirely from the car underbody, i.e., from a zone close to the ground.

Industry

ICI Resins is rewarded for efforts in China Preparation and perfection of trial formulations by ICI Resins has led to sales of ‘NeoRez’ polyurethane resin and ‘Winnofil’ thixotropes to Nan Ji paint in Shanghai for car underbody sealer products. This is ICI Resins' first business with the emerging automotive industry of the Peoples Republic of China.

Industry

Preparation and perfection of trial formulations by ICI Resins has led to sales of ‘NeoRez’ polyurethane resin and ‘Winnofil’ thixotropes to Nan Ji Paint in Shanghai for car underbody sealer products. This is ICI Resins' first business with the emerging automotive industry of the Peoples Republic of China.

The Analysis by Computer of a Motor Car Underbody Structure

Structural analysis techniques developed since the introduction of digital computers now allow the analysis of any three-dimensional, elastic structure made up from straight uniform beams and flat panels. A motor car underbody is not composed of these elements but by breaking it down into a large number of small elements, the complex components from which an underbody is assembled may be approximated to by these types of elements. In this paper we report the results of an analysis of a Ford Classic underbody and compare these with the results obtained from experimental tests made on an actual underbody removed from the production line.