Crashworthiness assessment considering the dynamic damage and failure of a dual phase automotive steel

Analyzing crash worthiness of the automotive parts has been posing a great challenge in the sheet metal and automotive industry since several decades. The present contribution will focus on one of the most urging challenges of the crash worthiness simulations, namely, an enhanced constitutive formulation to predict the failure and cracking of structural parts made from high strength steel sheets under impact. A hybrid extended Modified Bai Wierzbicki damage plasticity model is devised to this end. The material model calibrated using the experimental data covering high strain rate deformation, damage and failure successfully predicted the instability and subsequent response of the crash box under impact. Simulation results provide the deformation shape and deformation energy in order to predict and evaluate the vehicle crashworthiness. The simulations further helped in discovering the irrefutable impact of strain rate and stress state on the impact response of the auto-body structure. The strain rate is found to adequately affect the energy absorption capacity of the crash box structure both in terms of impact load and fold formation whereas the complex stress state has a direct association to the development of instability within the structure and early damage appearance within the folds

The prisoners' dilemma: A game theoretic approach to vehicle safety

This paper assessed the policy implications of the changing demand for passenger vehicles in Australia and debunked the myth that bigger vehicles are safer. In particular, we examined the increasing demand for small cars and four-wheel drive using the classic prisoners' dilemma framework in game theory. We found that the current emphasis on occupant protection may result in a pareto inferior outcome whereas a shift in the emphasis towards non-aggressiveness of a vehicle would result in a pareto superior outcome. Among the pure strategy equilibria, the one with only small cars provides the lowest overall level of road trauma. Furthermore, we found no mixed strategy equilibrium that would produce a lower level of trauma than the pure strategy equilibria, implying that mixing vehicle type would definitely increase road trauma. In a mixed fleet, however, medium cars produced the least trauma and thus were the safest type of passenger vehicle

Key issues in application of composites to transport aircraft

The application of composite materials to transport aircraft was identified and reviewed including the major contributing disciplines of design, manufacturing, and processing. Factors considered include: crashworthiness considerations (structural integrity, postcrash fires, and structural fusing), electrical/avionics subsystems integration, lightning, and P-static protection design; manufacturing development, evaluation, selection, and refining of tooling and curing procedures; and major joint design considerations. Development of the DC-10 rudder, DC-10 vertical stabilizer, and the DC-9 wing study project was reviewed. The Federal Aviation Administration interface and the effect on component design of compliance with Federal Aviation Regulation 25 Composite Guidelines are discussed

New Multiphase CP and DP 1000 MPa strength level grades for improved performance after hot forming

Pure martensitic steels have after hot forming limited performance in terms of rest ductility which limits the application in crash relevant parts. New steel grades were designed in the EU project HOTFORM including the corresponding process routes. These steel grades have ferritic-martensitic dual phase (DP) and martensitic-bainitic complex phase (CP) microstructures after hot forming process. The laboratory tests show an improved formability after hot forming. The basic concepts of the new alloys are explained. Furthermore, for validation of upscaling purposes a semi-industrial test is carried out and the results are discussed. The main application is for vehicle safety. This is evaluated by comparing the crash performance of these hot formed grades with cold rolled DP1000 and CP1000 for crash cans in a drop tower test.The research leading to these results was carried out in the framework of HOTFORM project with a financial grant of the Research Programme RFCS (Research Funds for Coal and Steel) under grant agreement (RFSR-CT-2015-00017)

Challenges in Vehicle Safety and Occupant Protection for Autonomous Electric Vertical Take-Off and Landing (eVTOL) Vehicles

The burgeoning electric Vertical Take-off and Landing (eVTOL) vehicle industry has generated a significant level of enthusiasm amongst aviation designers, manufacturers and researchers. This industry is determined to change the urban transportation paradigm from traditional ground-based vehicles (cars, taxis, buses) to air-based eVTOL vehicles which can be summoned, much like how conventional taxi services work currently. These new eVTOL vehicles are designed to be small and lightweight and operate autonomously without user intervention. There are many unknowns as to how the industry will mature. The logistics of creating a completely new category of vehicle along with its own set of rules are complex, and there are many known - and unknown - barriers to overcome. Some (of many) known barriers include airspace management, ground logistics, physical space, and, the vehicle design itself. There are many eVTOL vehicle manufacturers and organizations working these problems presently. This report will focus on one major barrier: the level of safety as it pertains to the framework of eVTOL vehicles. A high level of safety is necessary for the vehicles to gain acceptance as the public adapts to these autonomous ride-sharing services. An overview of current levels of transportation safety and some extrapolation into how eVTOL vehicles might compare is first presented. Next, a discussion categorizing the major differences between Crash Prevention and Crash Mitigation as it pertains to eVTOL vehicle safety is included with identification of current deficiencies. The report then expands into a framework for specific ideas that could use Crash Mitigation to improve vehicle safety through a crashworthy systems level approach with several designs highlighted. Finally, a brief discussion into the regulatory approach and potential guidelines as they pertain to new eVTOL vehicles is presented. Accordingly, much of the supplemental data will be taken from sources pertaining to either General Aviation (GA) aircraft, rotorcraft, or transport category aircraft, due to the lack of overarching data from eVTOL vehicles. As of this writing, the European Aviation Safety Agency has released a draft version of a VTOL Special Condition, with a comment period closing in late 2018. It is assumed that eventual expected operations and anticipated future regulations for VTOL vehicles will consist of some combination of these (and other) sources

Evaluation on crashworthiness and energy absorption of composite light airplane

[[abstract]]The main aim of this study was to explore the safety differences when using aluminum alloy and three different fiber reinforced composites as material for the cockpit and fuselage of light aircraft under crash landing. In accordance with the cockpit reduction amount stipulated by MIL-STD-1290A in which the reducing rates in all directions cannot exceed 15%, this study established the safety zones of impact speeds and impact angles. The overall safety zones of the carbon fiber reinforced composites and glass fiber reinforced composites cockpits were higher than that of the aluminum alloy cockpit by 38.56% and 32.12%, respectively. Among the four different fuselage materials, when carbon fiber reinforced composites was used as the cockpit material, except that the reducing rate for the crashing in the Y direction was slightly higher than the aluminum alloy cockpit, the reducing rate in the X direction and the inclined beam A direction during crashes were less than other materials, and the safety of its overall cockpit was also the most superior to other materials. The energy absorption capability of the aluminum alloy fuselage was better than the fuselages of all composite materials.[[notice]]補正完

NASA/FAA general aviation crash dynamics program

The program involves controlled full scale crash testing, nonlinear structural analyses to predict large deflection elastoplastic response, and load attenuating concepts for use in improved seat and subfloor structure. Both analytical and experimental methods are used to develop expertise in these areas. Analyses include simplified procedures for estimating energy dissipating capabilities and comprehensive computerized procedures for predicting airframe response. These analyses are developed to provide designers with methods for predicting accelerations, loads, and displacements on collapsing structure. Tests on typical full scale aircraft and on full and subscale structural components are performed to verify the analyses and to demonstrate load attenuating concepts. A special apparatus was built to test emergency locator transmitters when attached to representative aircraft structure. The apparatus is shown to provide a good simulation of the longitudinal crash pulse observed in full scale aircraft crash tests

Structural response of transport airplanes in crash situations

This report highlights the results of contractural studies of transport accident data undertaken in a joint research program sponsored by the FAA and NASA. From these accident data studies it was concluded that the greatest potential for improved transport crashworthiness is in the reduction of fire related fatalities. Accident data pertaining to fuselage integrity, main landing gear collapse, fuel tank rupture, wing breaks, tearing of tank lower surfaces, and engine pod scrubbing are discussed. In those accidents where the energy absorbing protective capability of the fuselage structure is expended and the airplane experiences major structural damage, trauma caused fatalities are also discussed. The dynamic performance of current seat/restraint systems are examined but it is concluded that the accident data does not adequately define the relationship between occupant response and the dynamic interaction with the seat, floor and fuselage structure