Finite Element Modelling of Car Hood Panel for Pedestrian Protection during Impact

Pedestrian protection during accidents is one of the important criteria in the design of new “pedestrian friendly cars†that is in compliance to the new regulations requirements for pedestrian and road users’ safety. In this study, the collision between headform impactors and vehicle hoods is simulated using FE models developed according to the European Enhanced Vehicle-Safety Committee (EEVC/WG17) regulations. The impact was simulated in LS-Dyna to study the hood performance in terms of pedestrian safety by evaluating the Head Injury Criteria (HIC). The performance of the hood was investigated by varying the section dimensions of the panel pillar with comparisons to the original dimensions. Results indicate that the section dimensions of the panel pillar is one of the keys to control the performance of hood during collision by reducing the HIC and the head injury risk level of pedestrian during accidents

Impact behaviour of aluminum particles upon aluminum, magnesium, and titanium substrates using high pressure and low-pressure cold spray

This study is focused on the impact and residual stress behaviour of aluminum component repair using aluminum powder via two different types of cold spray processes; high pressure cold spray (HPCS) and low-pressure cold spray (LPCS). It has been carried out via smoothed particle hydrodynamics simulations, comparing aluminum substrate with other lightweight materials such as titanium and magnesium. The obtained results have shown that the impact behaviour is influenced by velocity, porosity, deformation behaviour, flattening ratio, total energy and maximum temperature. The aluminum particles impacting on aluminum substrates using LPCS is slightly deformed, with the smallest flattening ratio leading to less pore formation between the particles. This has subsequently resulted in good coating quality. Furthermore, HPCS has contributed greatly to the deposition of particles on the heavier and harder substrate, such as titanium substrate. Thus, the overall result indicates that LPCS is better for repairing aluminum component compared to HPCS

CO2 capture for dry reforming of natural gas: Performance and process modeling of calcium carbonate looping using acid based CaCO3 sorbent

Several industrial activities often result in the emissions of greenhouse gases such as carbon dioxide and methane (a principal component of natural gas). In order to mitigate the effects of these greenhouse gases, CO2 can be captured, stored and utilized for the dry reforming of methane. Various CO2 capture techniques have been investigated in the past decades. This study investigated the performance and process modeling of CO2 capture through calcium carbonate looping (CCL) using local (Malaysia) limestone as the sorbent. The original limestone was compared with two types of oxalic acid-treated limestone, with and without aluminum oxide (Al2O3) as supporting material. The comparison was in terms of CO2 uptake capacity and performance in a fluidized bed reactor system. From the results, it was shown that the oxalic acid-treated limestone without Al2O3 had the largest surface area, highest CO2 uptake capacity and highest mass attrition resistance, compared with other sorbents. The sorbent kinetic study was used to design, using an Aspen Plus simulator, a CCL process that was integrated with a 700 MWe coal-fired power plant from Malaysia. The findings showed that, with added capital and operation costs due to the CCL process, the specific CO2 emission of the existing plant was significantly reduced from 909 to 99.7 kg/MWh

Thermal Stability of Rare Earth-PYSZ Thermal Barrier Coating with High-Resolution Transmission Electron Microscopy

Durability of a thermal barrier coating (TBC) depends strongly on the type of mixed oxide in the thermally grown oxide (TGO) of a TBC. This study aims on discovering the effect of thermal stability in the TGO area containing mixed oxides. Two different bondcoats were studied using high-resolution transmission electron microscopy: high-velocity oxygen fuel (HVOF) and air-plasma spray (APS), under isothermal and thermal cyclic tests at 1400 °C. The HVOF bondcoats were intact until 1079 cycles. In comparison, APS failed at the early stage of thermal cycling at 10 cycles. The phase transformation of topcoat from tetragonal to the undesired monoclinic was observed, leading to TBC failure. The results showed that the presence of transient aluminas found in HVOF bondcoat helps in the slow growth of α-Al2O3. In contrast, the APS bondcoat does not contain transient aluminas and transforms quickly to α-Al2O3 along with spinel and other oxides. This fast growth of mixed oxides causes stress at the interface (topcoat and TGO) and severely affects the TBC durability leading to early failure. Therefore, the mixed oxide with transient aluminas slows down the quick transformation into alpha-aluminas, which provides high thermal stability for a high TBC durability

Experimental and SPH study of cold spray impact on similar and dissimilar metals

In this study, the critical, maximum and optimum velocity of a single cold sprayed (CS) particle is estimated using the smoothed particle hydrodynamics (SPH) method by evaluating the impact shape coefficient of restitution, as well as the rebound and deposit energy ratio. The contact surfaces of the particle and the substrate are modelled as intersurface forces using the Dugdale– Barenblatt cohesive zone model. The application of SPH allows the simulation of the CS process without the use of mesh, thereby avoiding the disadvantages of the traditional numerical method in handling large deformations and tracing moving interfaces. The impact of CS particles is simulated using various powder and substrate materials. The influence of the materials on the optimum velocity and the coating quality is discussed. The reliability of the model is verified with CS experiments

Vein mechanism simulation study for deep vein thrombosis early diagnosis using CFD

Using a Computational Fluid Dynamics (CFD) technique, this work focus on the analysis of pressure, velocity, and vorticity of blood flow along the popliteal vein. Since the study of early stage of Deep Vein Thrombosis (DVT) becomes essential to prevent the pulmonary embolism (PE), those three parameters are analysed to assess the effect of different opening between two valves of a normal popliteal vein. When only one valve is simulated, the result of pressure shows that the highest and lowest velocities are 15.45 cm/s and 0.73 cm/s, respectively. From the visualization of observed data, however, the different size of orifice between the first and second valves influencing the velocity and vorticity of the blood flow. The rotational motion of blood particle at the same region increases the probability of blood accumulating which is associated with the development of thrombus. Thus, a series of experiment has been conducted by changing the size of valve orifice for the first and second valves along the vein distribution. The result of the CFD simulation shows a significant variation in blood flow in terms of velocity and vorticity

Simulation method for redesign of cars hood structure to achieve the requirements of pedestrian protection during accidents

Thousands of lives the world loss every year due to Pedestrian-Cars accidents and more have injuries. Pedestrian Friendly Cars option is a viable alternative solution to reduce the pedestrian fatalities number and mitigate the injuries during accidents. This study presents a numerical simulation design method for pedestrian safety according to European Enhanced Vehicle-Safety Committee (EEVC/WG17) regulations. This structure design method based on controlling the parameters that affects the performance of hood during pedestrian accident. The hood model has been built by using Soldworks software and simulating the impact process in LS-Dyna program for tests and results analyses. Finite Elements (FE) study analysis of head impactor model used in this investigation shows the extent of pedestrian injury risk can be minimized through the selection of appropriate design of car hood structure enhancing its performance. The results of the study concluded that the proposed structure design method for car hood is an effective method to obtain the "Pedestrian Friendly Cars" which improves the performance of the hood during the impact accidents and provide better protection and more pedestrian safety. 2020 Author(s).Scopu