The requirement for improved safety on the roads is reflected in the increasing legislation and higher consumer standards worldwide. Every new generation of vehicles new and more stringent statutory and other safety standards are introduced. Even before the first prototype vehicle is tested, CDH AG vehicle safety specialists are engaged early in the virtual design stage to ensure that such new safety standards will be satisfied.
For a wide range of vehicle crash scenario, the statutory and consumer standards require that sufficient post-crash space is available for the vehicle occupants. This results in various crash load cases.
- in compliance with statutory requirements of FMVSS208 and ECE R96
- in compliance with consumer-organization standards such as IIHS Small Overlap oder EuroNCAP pillar impact
- in compliance with statutory requirements of FMVSS214 and ECE R95
- in compliance with consumer-organization standards such as IIHS side crash oder EuroNCAP Side Crash
- in compliance with statutory requirements of FMVSS301
- in compliance with consumer-organization standards EuroNCAP
- in compliance with statutory requirements, e.g. Roof crush
Low speed crash cases such as bumper contact while parking are also addressed in the analysis load cases. This ensures that the vehicle structure is tolerant to minor impacts and that the associated repair costs, if any, are minimized. Through the application of crash simulation tools, CDH specialists can derive the best structural layout and characteristics for the body components, including dimensions material properties. To address the requirements of multiple vehicle functions, effective structural design requires the use of multiple discipline optimization tools at the various stages of design including:
- Abstract concept modelling
- Topology optimzation
- ody panel thickness optimization
- Robustness and reliability calculations
In structural design for occupant safety, focus is placed on the design of components with which the vehicle occupant could come into contact in the event of a collision. The performance of restraining systems such as airbag and seatbelts is of primary importance. However, components such as seats and dashboard are designed to reduce the possibility of injury to vehicle occupants.
The use of modern sensor equipment allows the instantaneous identity of crash severity. This is then factored with the physical characteristics of the passenger and the position of the seat to optimally trigger the air bag. Air bag control parameters can be included in the crash simulation calculations. By performing parameter studies in the computer, optimal characteristics for the air bag parameters such as gas-generator and seat belt force limiter can be found. The design of an optimal airbag system also requires that occupant out-of-position situations be simulated. The reliable prediction of restraining system behavior, requires the availability of mathematical models for the gas ignition process and the unfolding process of the packaged airbag.
- compliance with statutory and consumer-organization requirements , e.g. FMVSS208 5%ile HIII Dummy
- compliance with statutory and consumer-organization requirements, such as IIHS SiD IIs
- compliance with statutory and consumer-organization requirements, e.g. EuroNCAP
Because of the requirements for multiple design parameters and multiple load cases the use of automatic optimization tools is mandatory. Depending on the particular analysis discipline, one or more of the following methods are indicated:
- Design of Experiments(DoE)
- Gradient-based optimization methods
- Evolutionary Optimization algorithms
- Stochastic Optimization algorithms
In addition to the requirements for occupant safety, vehicle design criteria to reduce injuries to pedestrians in the event of contact have become increasingly important.
The potentially conflicting requirements of styling, space availability and safety can be addressed with the help of advanced analysis tools. Through simulation, solutions achievable by the use of new materials or the selection of active or passive safety devices can be examined in the early stages of vehicle design. In addition to offering its analysis services, CDH AG has long experience in the coordination of the testing activities that are necessary to provide material and correlation data for analysis. Our services for testing coordination include test-rig planning and comparisons between test and simulation results. We can also provide the project management communication and coordination services to ensure that the results of analysis and test activities are implemented in the vehicle design. The spectrum of CDH AG capabilities in this area includes the simulation and evaluation of the sensor signals that play an important role in pedestrian protection systems. The load cases addressed include:
- Head impact
- Hip Impact
- Leg impact
For each of the above laid cases, the statutory and consumer-organization requirements in Europe (EuroNCAP) and Japan (JapanNCAP) must be satisfied.
High Voltage Battery Protection
The importance of electrified vehicles is rapidly increasing, whether as a hybrid (HEV), plug-in hybrid (PHEV), pure electric vehicle (BEV) or as a fuel cell vehicle (FCEV). However, the technology of high-voltage systems also entails new risks, e.g. the risk of a short circuit or fire or the failure of a hydrogen tank. Precautions must be taken for all possible scenarios of real accidents; the requirements go far beyond existing legal crash requirements.
Body in White
Already in the concept phase, the body in white of the vehicle must be designed not only to protect the occupants, but also to protect the HV system. CDH specialists find intelligent lightweight solutions to achieve these goals optimally.
In the event of an accident, the battery housing protects the battery cells inside from external loads. For this purpose, compliance with legal requirements must be proven at component level. With the help of FEM, CDH optimizes the stiffness and strength of the battery housing even before the first prototypes.
The integration of the entire battery into the vehicle environment is another focus of HV safety. Due to the high masses, very large inertial forces act on the battery in the event of an accident; these must be transferred into the body using previously defined force paths. CDH is able to precisely determine the transmitted forces and to dimension the connection technology to be selected or the form-fitting installation situation.
The Li-ion cells represent the vulnerable core of HV technology; all measures serve to protect them. In the simulation a realistic representation of their mechanical behaviour in the simulation is the prerequisite for predictive calculations.
All live components are to be examined in accordance with their behaviour during a possible accident. Battery chargers, power electronics or PTC heating elements need to be analyzed to their structural load and timing of load. Possible damage may only occur late, after the power supply has been switched off.
The same requirements as for the electronic components also apply to all HV cables.