Car Bonnet Research Articles

Regulatory testing for safety: The mathematics of broad-based results

Testing of the safety of manufactured products is typically conducted under a specified set of conditions. For example, when projecting an instrumented headform at the front of a car to assess the pedestrian safety of that model of car, the speed of the headform is specified. But surely, if they were asked, the public and policymakers would say that the result at one speed is a rather artificial measure, and they instead wish to know the average level of safety across real-world impact scenarios. One possible solution is to directly test across the range of conditions and combinations of conditions. However, manufacturers typically want to economise by conducting fewer tests. This article considers how to determine a product's saftey for a range of conditions, while also being economical with the testing. What is proposed has three steps. The first is to generalise the quantity observed in test conditions to what would be observed under different conditions. This is likely to involve a theory and a formula. For example, in a headform impact test the quantity observed might be HIC (the Head Injury Criterion), the condition that varies might be impact speed, and a formula might be available for the dependence of HIC on speed. The second is to convert the test quantity to something that is meaningfully averaged. This might be the dollar cost associated with a particular level of HIC, or perhaps the probability of death. The third is to obtain the average, by integration over the condition that varies from crash to crash (such as impact speed). In principle, this procedure is quite general and applicable to many other forms of testing. Good information is required for the three steps, but this is inherent in aiming for a broad-based result, rather than due to the method. References P. H. Deitz. A V/L taxonomy for analyzing ballistic live-fire events. Proceedings of the 15th International Symposium on Military Operational Research , 1998. http://ismor.cds.cranfield.ac.uk/15th-symposium-1998 R. G. Herbert and D. C. McWhannell. Shape and frequency composition of pulses from an impact pair. J. Eng. Ind. 99:513–518, 1977. doi:10.1115/1.3439270 K. H. Hunt and F. R. E. Crossley. Coefficient of restitution interpreted as damping in vibroimpact. J. Appl. Mech. 42:440–445, 1975. doi:10.1115/1.3423596 T. P. Hutchinson. Dependence of the Head Injury Criterion and maximum acceleration on headform mass and initial velocity in tests simulating pedestrian impacts with vehicles. J. Biomech. Eng. 135:114508, 2013. doi:10.1115/1.4025331 T. P. Hutchinson. Experimental injury: Inference from proxy observations in a test to the real-world average. J. Battlefield Tech. 18(1):1–6, 2015. http://search.informit.com.au/documentSummary;dn=958266262006914;res=IELENG T. P. Hutchinson, R. W. G. Anderson and D. J. Searson. Pedestrian headform testing: Inferring performance at impact speeds and for headform masses not tested, and estimating average performance in a range of real-world conditions. Traffic Inj. Prev. 13:402–411, 2012. doi:10.1080/15389588.2012.660252 T. P. Hutchinson, D. J. Searson, R. W. G. Anderson, J. K. Dutschke, G. Ponte and A. L. van den Berg. Protection of the unhelmeted head against blunt impact: The pedestrian and the car bonnet. Proceedings of the Australasian Road Safety Research, Policing and Education Conference , 2011. http://acrs.org.au/files/arsrpe/Protection%20of%20the%20unhelmeted%20head%20against%20blunt%20impact.pdf W. Kokinakis and J. Sperrazza. Criteria for incapacitating soldiers with fragments and flechettes. Technical Report 1269, Ballistic Research Laboratories, Aberdeen Proving Ground, MD, 1965. http://www.dtic.mil/dtic/tr/fulltext/u2/359774.pdf R. VanAmburg. An approach to analyze personnel injury of reflective spall from small-arms protective body armor. Technical Report ARL-TR-5595, U.S. Army Research Laboratory, Aberdeen Proving Ground, MD, 2011. http://www.dtic.mil/dtic/tr/fulltext/u2/a550618.pdf R. B. Webby, P. T. Adamson, J. Boland, P. G. Howlett, A. V. Metcalfe and J. Piantadosi. The Mekong–-applications of value at risk (VaR) and conditional value at risk (CVaR) simulation to the benefits, costs and consequences of water resources development in a large river basin. Ecological Modelling , 201:89–96, 2007. doi:10.1016/j.ecolmodel.2006.07.033

Squaroglitter: A 3,4-Connected Carbon Net.

Theoretical calculations are presented on a new hypothetical 3,4-connected carbon net (called squaroglitter) incorporating 1,4 cyclohexadiene units. The structure has tetragonal space group P4/mmm (No. 123) symmetry. The optimized geometry shows normal distances, except for some elongated bonds in the cyclobutane ring substructures in the network. Squaroglitter has an indirect bandgap of about 1.0 eV. The hypothetical lattice, whose density is close to graphite, is more stable than other 3,4-connected carbon nets. A relationship to a (4,4)nanotube is explored, as is a potential threading of the lattice with metal needles.

Computational Analysis of Frontal Area of a Front Grill Passenger Car

Designing the front grill with the focus on analyzing the flow from outside to the inside of a passenger car bonnet is very important in the automotive industry. This study was done to increase performance of the flow through the analysis on the effect of aerodynamic flow through the front grill by designing different cases of frontal areas of the front grill. Velocity at 34 m/s at steady condition were done to obtain the flow structure around a passenger car as well as the front grill of a passenger car. Analysis was taken inside the wind tunnel as the boundary condition. The grid generation was based on the tetrahedral unstructured meshes. Result obtain was compared with past experiment data. It was found that an appropriate design of frontal area of front grill can improved the stability of a car and the heat surrounding inside the car bonnet. Finally, the aerodynamics of the most suitable design of front grill was introduced and analyzed.

A hybrid framework for nonlinear dynamic simulations including full-field optical measurements and image decomposition algorithms

Innovative designs of transport vehicles need to be validated in order to demonstrate reliability and provide confidence. It is normal practice to study the mechanical response of the structural elements by comparing numerical results obtained from finite element simulation models with results obtained from experiment. In this frame, the use of whole-field optical techniques has been proven successful in the validation of deformation, strain, or vibration modes. The strength of full-field optical techniques is that the entire displacement field can be acquired. The objective of this article is to integrate full-field optical measurement methodologies with state-of-the-art computational simulation techniques for nonlinear transient dynamic events. In this frame, composite car bonnet frame structures of dimensions about 1.8 m × 0.8 m are considered. They have been tested in low-velocity mass-drop impact loading with impact energies ranging from 20 to 200 J. In parallel, simulation models of the car bonnet frame have been developed using layered shell elements. The Zernike shape descriptor approach was used to decompose numerical and experimental data into moments for comparison purposes. A very good agreement between numerical and experimental results was observed. Therefore, integration of numerical analysis with full-field optical measurements along with sophisticated comparison techniques can increase design reliability.

Quantitative determination of mar resistance of high gloss coatings

Nowadays, ones are prone to purchase consumer products on their esthetic aspect as much as functionality. Even if minor surface damages are formed, it might deteriorate the original appearance of the surface and lower the esthetic satisfaction. Common surface damages include cracks, delamination, and scratch/mar arising from mechanical abrasion. As one of protective layers, high gloss coatings are gradually getting more attention for both esthetic and functional applications. In particular, housings of consumer electronics, cases of cellular phone, as well as interior parts of automobile are fabricated with high gloss surfaces to provide a luxury sensation and emotional quality. Therefore, any subtle surfaces damages (i.e., mar and scratch) on the coatings are absolutely undesirable. A mar is a mark caused by a sliding contact, which is too minute to be perceived by the naked human eyes alone. Nevertheless, mar becomes visible with its large quantities present and/or with an observer in different angle views. An example is typical damage found on car bonnet after an automatic car wash, which is damaged by a relatively low level of applied load. On the other hand, scratches are regarded as visible surface damages and grooves that the human eyes can perceive. The damages are commonly associated with surface deformation caused by a heavy sliding. Typically, this is brought about by a phenomenon termed “stress whitening” or “cutting” where the deformation is more severe than subtle mar damage. Many coatings industries have used to evaluate mar resistance using their own test methodology, such as the pencil hardness test, peel-out test, the knife test, etc.. However, these standards only emphasized the test methodology, without explicit description about quantitative determination of the mar damage on coating surfaces. It is non-trivial to quantitatively evaluate the degree of subtle surface deformation (i.e., mar damage). The main aim of the current study is to explore the mar behavior under a low mechanical abrasion condition. The effectiveness of a new approach for evaluating the mar resistance of high-gloss coatings is demonstrated. The observed mar behavior is correlated with the changes in gloss and luminance in relation to surface roughness.

Frequency response functions of shape features from full-field vibration measurements using digital image correlation

The availability of high speed digital cameras has enabled three-dimensional (3D) vibration measurement by stereography and digital image correlation (DIC). The 3D DIC technique provides non-contact full-field measurements on complex surfaces whereas conventional modal testing methods employ point-wise frequency response functions. It is proposed to identify the modal properties by utilising the domain-wise responses captured by a DIC system. This idea will be illustrated by a case study in the form a car bonnet of 3D irregular shape typical of many engineering structures. The full-field measured data are highly redundant, but the application of image processing using functional transformation enables the extraction of a small number of shape features without any significant loss of information from the raw DIC data. The complex bonnet surface on which the displacement responses are measured is essentially a 2-manifold. It is possible to apply surface parameterisation to ‘flatten’ the 3D surface to form a 2D planar domain. Well-developed image processing techniques are defined on planar domains and used to extract features from the displacement patterns on the surface of a specimen. An adaptive geometric moment descriptor (AGMD), defined on surface parametric space, is able to extract shape features from a series of full-field transient responses under random excitation. Results show the effectiveness of the AGMD and the obtained shape features are demonstrated to be succinct and efficient. Approximately 14 thousand data points of raw DIC measurement are represented by 20 shape feature terms at each time step. Shape-descriptor frequency response functions (SD-FRFs) of the response field and the loading field are derived in the shape feature space. It is seen that the SD-FRF has a similar format to the conventional receptance FRF. The usual modal identification procedure is applied to determine the natural frequencies, damping factors and eigen-shape-feature vectors from the SD-FRF. Natural frequencies and mode shapes from a finite element (FE) model are correlated with the experimental data using the cosine distance between the shape feature vectors with 20 terms. There are numerous benefits of using image decomposition to analyse 3D DIC measured data, including (1) representation of the raw measurement data with efficiency and succinctness; (2) determination of the FRF of any point on the specimen by the use of the full-field shape features; and (3) elimination of DIC measurement noise. Also, the SD-FRF is potentially ideal for cases of field excitation of structures.

Palynological investigation of haze dust in Ayetoro-Itele Ota, Southwest Nigeria

The biological contents of the March 2010 hazy dust in Nigeria deserve verification due to the attendant panic it brought to the public. 3 g of dust deposited on the car bonnet of one of the authors was treated chemo-palynologically and microscopic study of the residue was carried out. The study reveals that the dust was rich in pollen grains, fungal spores and hyphae. No pteridophyte spore was recovered. High proportion of diatoms almost doubling that of the sporomorphs was recorded. Savanna and derived savanna pollen grains and the Sahara desert freshwater diatoms recovered indicate that the dust was still the harmattan borne by the Northeast Trade winds though coming heavily and lately in March instead of the traditional January. This indicates a delay in the northward movement of the Inter Tropical Discontinuity (ITD) with the consequential abnormal hazy atmosphere. Some typical Sudan and Sahel vegetations’ pollen were not recovered inspite of the dust crossing over them, perhaps due to being dropped along the way or March not being their flowering periods. Pollen of Vitex cf. doniana dominates the palynoflora along with Isoberlinia doka which might be candidate culprits for clinical conditions in the experimental area. Key words: Saharan dust, palynoflora, diatoms, intertropical discontinuity.

Validation of Impact Simulations of a Car Bonnet by Full-Field Optical Measurements

Innovative designs of transport vehicles need to be validated in order to demonstrate reliability and provide confidence. The most common approaches to such designs involve simulations based on Finite Element (FE) analysis, used to study the mechanical response of the structural elements during critical events. These simulations need reliable validation techniques, especially if anisotropic materials, such as fibre reinforced polymers, or complex designs, such as automotive components are considered. It is normal practice to assess the accuracy of numerical results by comparing the predicted values to corresponding experimental data. In this frame, the use of whole field optical techniques has been proven successful in the validation of deformation, strain, or vibration modes [1]. The strength of full-field optical techniques is that the whole displacement field can be visualized and analyzed. By using High Speed cameras, the Digital Image Correlation (DIC) method can be applied to highly non-linear dynamic events and deliver quantitative information about the three-dimensional displacement field [2].

Application of High Speed Image Correlation for Measurement of Mode Shapes of a Car Bonnet

For the analysis of vibrations and mode shape extraction in particular the use of optical full-field measurement techniques has grown during the last years. Beside techniques like Digital Speckle Pattern Interferometry, Moiré, Thermography or Photoelasticity the Digital Image Correlation techniques have already been successfully proven to be an accurate displacement analysis tool for a wide range of applications.

Influence of pedestrian head surrogate and boundary conditions on head injury risk prediction

The objective of the present work is to investigate the influence of head models and boundary conditions on the head response in the case of pedestrian accidents. Simulations have been carried out, regarding results both in terms of global parameters and more detailed intracerebral mechanical parameters. Three head models have been used (ISO headform, Hybrid III head and ULP head Finite Element Model) for these simulations, either considered as isolated heads or coupled with the whole body. It was shown that inertial properties of Hybrid III head are closed to the human head, which strongly influences rotational acceleration and also intracerebral shearing. When coupled to the whole body, it appeared that initial car bonnet deformation induced by shoulder or back leads to dramatic head loading. As a whole, the results obtained demonstrate the necessity of taking into account more realistic head inertia and boundary conditions for future pedestrian head impact standard development.

MODEL VALIDATION AND FE ANALYSIS OF THE HEAD BONNET IMPACT

The directive 2003/102/CE intends to reduce the injuries of the pedestrians during frontal impact with passenger cars. The directive describes the device that must be employed to simulate pedestrian head: HIC is used to evaluate the severity of the impact. This work has two goals: to realize a FE model of pedestrian headform impactor; to optimize the car bonnet structure in order to reduce the accelerations and consequently the HIC (Head Injury Criteria) [Schmitt,2007]

Development of Short-Carbon-Fiber-Reinforced Polypropylene Composite for Car Bonnet

In this paper, short-carbon-fiber-reinforced polypropylene (SCF/PP) composites were prepared with melt blending and hot-pressing techniques. The tensile properties, flexural properties, hardness, and work of fracture (WOF) of this composite were investigated. Thermal stability of the composite was studied via the thermal gravimetric analysis (TGA). Finally, the mechanical properties of this composite were compared to mechanical properties of steel car bonnet in order to choose for car bonnet application. The properties of the composite prepared by 10% SCF/PP is comparable with the properties of carbon steel.

Characteristics of 3.5 kg pedestrian headform impactor prototypes developed by JAMA–JARI and ACEA–TNO

In 2004, the officially announced Japanese standard for the evaluation of car–front safety performance in terms of pedestrian child head protection required a 3.5 kg headform impactor as a test tool simulating a child pedestrian head. Currently, ACEA–TNO have jointly developed a 3.5 kg headform impactor in Europe. The primary aim of the present study is to investigate the availability of the 3.5 kg ACEA–TNO headform impactor in terms of the Japanese standard. Meanwhile, JAMA–JARI have together developed a 3.5 kg headform impactor in Japan. The secondary aim of our study is to present the physical characteristics and measured head injury criteria (HIC) of the JAMA–JARI and ACEA–TNO headform impactors obtained here as a point of reference for the formulation of the Global Technical Regulation (GTR) standards now under way. The technical specifications regarding mass, outer diameter, moment of inertia, location of centre of gravity, seismic mass location of accelerometers, natural frequency, and biofidelity of these headform impactor prototypes were investigated for each of the respective JAMA–JARI and ACEA–TNO headform impactor prototypes. The skin performance of these prototypes was also determined in terms of Shore hardness, relation of compressive force and deformation, high-velocity certification characteristic, and impact durability against a car bonnet. HIC obtained by both prototypes in car-front impact tests at various locations were also discussed.

Development of JAMA—JARI pedestrian headform impactor in compliance with ISO and IHRA standards

Head injuries are the most common cause of pedestrian deaths in car-pedestrian accidents. To reduce the severity of such injuries, the International Organization for Standardization (ISO) and International Harmonized Research Activities (IHRA) have proposed subsystem tests in which child and adult headform impactors are impacted upon a car bonnet top. The ISO and IHRA designated the mass of the child headform impactor as 3.5 kg (i.e., the average mass of a 6-year-old child's head), and that of an adult as 4.5 kg. However, such headform impactors have not been developed so far. Therefore, in the present study, new child and adult headform impactors according to the requirements of the ISO and IHRA subsystem test procedures have been designed and developed. The technical specifications, including the moment of inertia, the location of the centre of gravity, the location of the seismic mass of accelerometers, and natural frequency of the impactors, are determined. Then, the results of biofidelity certification tests of the skin of these newly developed impactors are investigated. The results show that the technical specification of the manufactured child and adult headform impactors fulfilled the ISO and IHRA requirements.

CONVECTIVE AND RADIATIVE THERMAL TRANSFER WITH MULTIPLE REFLECTIONS: ANALYSIS AND APPROXIMATION BY A FINITE ELEMENT METHOD

We study a 3D steady-state thermal model taking into account heat transfer by convection, diffusion and radiation with multiple reflections (grey bodies). This model is a nonlinear integrodifferential system which we solve numerically by a finite element method. Some results of existence and uniqueness of the solution are proved, the numerical analysis is detailed, error estimates are given and two-dimensional numerical results of thermal exchanges under a car bonnet are presented.

Automotive local area networks

One of the electronics innovations in the automotive industry in recent years has been the development of data-bus systems for the control of a wide range of electronics functions now common in the average car. How have the systems been developed, and how will they stand up to the harsh environment to be found under the average car bonnet?

CARBON DIOXIDE SUPPLY AND NET PHOTOSYNTHESIS

CARBON DIOXIDE SUPPLY AND NET PHOTOSYNTHESIS