Sharif Digital Repository

The effect of spot welding failure, flange location, sheet metal thickness, glue presence in foam-wall contact area, and foam filling on the bending crash performance and the collapse mechanism of empty and foam-filled box-beams is investigated. It is observed that the flange location in box-beams controls spot welds force, the energy absorption capacity of box-beams, and collapse behavior of the sections. As a result, the definition of spot weld failure criterion is inevitable in most cases. A survey on the effect of slight aluminium foam filling (12% mass increase) shows that the specific energy absorption value (SEA) and the energy dissipation performance of a filled section can even... 

In Euro NCAP standard, adult protection is one of the most important rating scores with 50% weight factor while child protection and pedestrian protection are accounted into consideration with 20% weight factor. For adult protection testing, three tests are required to perform: (1) side impact, (2) pole impact, (3) front impact. In the side impact test, dummy's head, chest, shoulder, thorax, ribs, abdomen, pelvic and femur must be studied to evaluate the rating score. Crashworthiness of a car during side impact can describe the score rated for that car. In this paper the goal is to determine the crashworthiness of side doors and B-pillar in side impact crash est by simulation using LS DYNA... 

In side impact test which is one out of three tests of Euro NCAP standard, front and rear doors and B pillar are most absorbance parts among vehicle body parts. Passengers are highly in danger while side crash, because of the distance between passenger's head and vehicle body. In this paper effect of material and thickness of doors and B-pillar and their absorbed energy during crash and improvement of its crashworthiness with respect to light weight design are studied using LS DYNA solver. The objective of this paper is to propose a material for doors and B-pillar with a specified thickness to achieve maximum absorbed energy and minimum weight. The shape of the doors and B-pillar remains... 

The effect of vehicles’ compatibility on the odds of death or injury of drivers involved in two-vehicle crashes was investigated. This was done through indexing Crashworthiness (CW) and Crashaggressivity (CA) of major vehicle types. For this purpose, a dataset consisting the information about 551,138 drivers involved in two-vehicle crashes in Iran was used and a two-step analysis framework was employed. In this regard, the Classification and Regression Tree (CART) method was applied in the first step to identify the most significant factors contributing to drivers’ Injury Status (IS). Next, Generalized Estimating Equations (GEE) with a Binomial distribution and a Logit link function were... 

The effect of vehicles’ compatibility on the odds of death or injury of drivers involved in two-vehicle crashes was investigated. This was done through indexing Crashworthiness (CW) and Crashaggressivity (CA) of major vehicle types. For this purpose, a dataset consisting the information about 551,138 drivers involved in two-vehicle crashes in Iran was used and a two-step analysis framework was employed. In this regard, the Classification and Regression Tree (CART) method was applied in the first step to identify the most significant factors contributing to drivers’ Injury Status (IS). Next, Generalized Estimating Equations (GEE) with a Binomial distribution and a Logit link function were... 

The effect of vehicles’ compatibility on the odds of death or injury of drivers involved in two-vehicle crashes was investigated. This was done through indexing Crashworthiness (CW) and Crashaggressivity (CA) of major vehicle types. For this purpose, a dataset consisting the information about 551,138 drivers involved in two-vehicle crashes in Iran was used and a two-step analysis framework was employed. In this regard, the Classification and Regression Tree (CART) method was applied in the first step to identify the most significant factors contributing to drivers’ Injury Status (IS). Next, Generalized Estimating Equations (GEE) with a Binomial distribution and a Logit link function were... 

We study experimentally the axial crushing behavior and crashworthiness characteristics of thin-walled steel tubes containing annular grooves. The grooves determine the positions of the folds and control the buckling mode of deformation. In the present work we aim to improve the uniformity of the load-displacement behavior and to predict the energy absorption capacity of the tubes. Grooves are cut circumferentially and alternately inside and outside the tubes at predetermined intervals. Quasi-static axial crushing tests are performed with different groove distances. Photographs are taken during axial buckling and the specimens after crushing are sectioned axially to carry out the... 

In the present study, crashworthiness characteristics of thin-walled steel tubes containing annular grooves are studied. For this purpose, the grooves are introduced in the tube to force the plastic deformation to occur at predetermined intervals along the tube. The aims are controlling the buckling mode and predicting energy absorption capacity of the tubes. To do so, circumferential grooves are cut alternately inside and outside of the tubes at predetermined intervals. Quasi-static axial crushing tests are performed and the load-displacement curves are studied. Theoretical formulations are presented for predicting the energy absorption and mean crushing load. It is found a good agreement... 

The initial buckling load of a tube corresponds to the peak load in the first buckling cycle. In practice, this load is very important for crashworthiness design that gives an indication of the force required to initiate collapse and hence begin the energy absorption process. In this paper, the effects of grooves on the initial buckling load of thin-walled tubes under axial compression are investigated. The grooves are introduced in the tube to force the plastic deformation to occur at predetermined intervals along the tube. The aims are improve the uniformity of the load-displacement behaviour of axially crushed tubes, predict and control the collapse load of the tube. An analytical study... 

To assess a car under the Euro New Car Assessment Program (Euro-NCAP), Adult Occupant Protection is one out of three parameters which need to be calculated with a weight factor of 50% while the other parameters, Child Occupant Protection and Pedestrian Occupant Protection, have a weight factor of 20%. The Pole Side Impact Test, beside two other tests, Side and Front Impact, is also required to calculate the Adult Occupant Protection. It shows how important the Pole Side Impact Test is and what an effective role it has in the car rating assessment. In this paper, the objective is to evaluate the effect of thickness on the energy absorbed by the side doors and the B pillar and its... 

In this paper the objective is to study the effect of the material and thickness of the side doors and B pillar on crashworthiness and the energy absorbed in order to select a proper material and an optimized thickness to approach a five star car concept based on the Euro New Car Assessment Program (Euro-NCAP) testing Pole Side Impact. In this matter, four materials and five thicknesses have been chosen for the vehicle model and a total of twenty simulations have been conducted. The results showed that the best selected materials and thicknesses were high strength Steel 204M with a thickness of 1.2mm for side doors and 0.65mm for the B pillar, however, it is important to note that this... 

Pole Side Impact Tes is one out of three crash tests described by Euro NCAP standard for star rating of a vehicle and is required for assessing the Adult Occupant Protection. In this paper the goal is to determine the crashworthiness of side doors and B pillar in a Pole Side Impact Test based on Euro New Car Assessment Program (Euro-NCAP) using computer and simulation method. In this matter, a vehicle model has been prepared and meshed using Hypermesh and CATIA. The velocity of 29 km/h has been assigned to the vehicle which was on top of a cart while the pole has been assigned as a rigid static object based on Euro NCAP requirements specifically. Results show that different amounts of energy... 

The evermore widespread use of microscopic traffic simulation in the analysis of road systems has refocused attention on sub models, including car-following and lane-changing models. In this research a microscopic model is developed which combines car-following and lane-changing models and describes driver behaviour as a crash risk reduction process of drivers. This model has been simulated by a cellular automata simulator and compared with the real data. It has been shown that there is no reason to consider the model invalid for drivers' behaviour in the basic segments of freeways in Iran, during not-congested conditions. Considering that uncertainty of position of vehicles is caused by... 

The crushing behaviour of dynamically loaded metal foam-filled square columns has been investigated using an extended version of the existing self-similar pressure dependent constitutive model for metal foams. The model has been implemented in ABAQUS/Explicit and analyses have been conducted using different approaches to model the uniaxial and hydrostatic hardening behaviour of metal foams. A practical and reliable procedure to approximate the observed anisotropic behaviour within the computational framework of isotropic plasticity is introduced. The comparison between the available experimental and newly generated numerical results is presented in order to illustrate the accuracy and... 

In this study, we consider a capacitated location–multi-allocation–routing problem with population-dependent random travel times. The objective is to find appropriate locations as server locations among the candidate locations, allocate the existing population in each demand node to server locations, and determine the movement path of each member to reach its corresponding server with respect to the simultaneous change of the random travel times so that the expected total transportation time is minimized. In our study, the concept of population-dependent random travel times incurs two issues: (1) consideration of some random factors in computing the travel times and (2) impact of the... 

To tackle the air pollution issues, Plug-in Hybrid Electric Vehicles (PHEVs) are proposed as an appropriate solution. Charging a large amount of PHEV batteries, if not controlled, would have negative impacts on the distribution system. The control process of charging of these vehicles can be centralized in parking lots that may provide a chance for better coordination than the individual charging in houses. In this paper, an optimization-based approach is proposed to determine the optimum PHEV parking capacities in candidate nodes of the distribution system. In so doing, a profile for charging and discharging of PHEVs is developed in order to flatten the network load profile. Then, this... 

There is a growing concern, in the last decade, about the environment and social footprint of business operations. The subject of supply chain sustainability, simultaneously considering economic, environment and/or social values, has gained attention in the academia and from the industry. Particularly for deteriorating and seasonal products, such as fresh produce, the issues of timely supply and disposal of the deteriorated products are of high concerns. This research develops a new replenishment policy in a centralized sustainable supply chain for the deteriorating items. The model considers inventory and transportation costs, as well as the environmental and social impacts, with several... 

Dissimilar joining of aluminium and steel, especially using resistance spot welding as a critical process in vehicle manufacturing, is a key challenge for multi-materials lightweight design strategy. Controlling the formation and growth of Al5Fe2 intermetallic is the outstanding issue for producing high strength crash-resistance Al/steel dissimilar resistance spot welds. This critical assessment highlights the current understating regarding factors affecting the joint properties and approaches to control the interfacial reaction. Finally, the unresolved scientific challenges are discussed with the goal of shedding light on the path forward to produce reliable metallurgical bonding between... 

With anticipated proliferation of electric vehicles and distributed generations in near future, dynamic thermal rating (DTR) as a tool for unlocking network capacities, is becoming critical for distribution network operators. DTR is gaining a great and still growing focus of attention in today's power industries. However, potential benefits of DTR, although have been envisioned to be significant, have not yet been studied quantitatively. This paper intends to comprehensively assess the potential impacts of DTR on the performance of a realistic Finnish distribution network. For doing so, first a step-by-step procedure is devised. Then, weather data and loading information of circuits in the...