**5. Crash worthiness and crash tests**

The occupant safety and vehicle reliability are the fundamental topics that should be developed against collisions for the crash worthiness. Although the technology is evolved in many fields especially for the materials science comprehending composite materials and withal super collapsible beams to absorb impact energy, again if we are not able to provide a safe drive for the occupant or the vehicle it is going to be a fact that can be concluded with the injuries or fatality for the driver, passengers or the people outside while the vehicle face with the physical damage like self-destruction as a result of collision to the wall, barrier or a structure; accident with another vehicle via front, behind or side impacts; and maybe a rollover incident by some other effects. These are by definition may differ from one incident to another defining the accidents of vehicles even for the autonomous systems. Whatever happens, the engineers should design a structure that can able to absorb some of the energy by collapsing itself or deforming to an adequate level to protect the human beings. If the structure is too rigid, there is an amplification occurs and affect everything in a poor way that is transferring the acceler‐ ations to the occupants causing worse situation. Therefore, even for the safety and reliability, optimum way is better to protect lives against accidents.


#### **Figure 5.** Crash test modes.

**•** Door Locks and Door Retention Components,

**•** Bus Emergency Exits and Window Retention and Release,

**•** School Bus Passenger Seating and Crash Protection,

**5. Crash worthiness and crash tests**

In another perspective for the crash testing, in the internet site of the crash network [17] expresses the headings in different groups: interior testing, dash board, frontal impact, side impact, steering wheel, seats, seat belts, rear impact, rollover, head rests, and roof crush. Considering the developments in the vehicle industry including automobiles and aircrafts, etc., especially the UAVs, many countries trying to improve new methodologies against the collisions comprising hundreds of standards. The major idea for the crash worthiness is protect the occupants or all beings, and eliminate or diminish the damages caused by the collisions.

The occupant safety and vehicle reliability are the fundamental topics that should be developed against collisions for the crash worthiness. Although the technology is evolved in many fields especially for the materials science comprehending composite materials and withal super collapsible beams to absorb impact energy, again if we are not able to provide a safe drive for the occupant or the vehicle it is going to be a fact that can be concluded with the injuries or fatality for the driver, passengers or the people outside while the vehicle face with the physical damage like self-destruction as a result of collision to the wall, barrier or a structure; accident

**•** Seating Systems,

66 Autonomous Vehicle

**•** Seat Belt Assemblies,

**•** Windshield Mounting, **•** Child Restraint Systems, **•** Side Impact Protection, **•** Roof Crush Resistance,

**•** Motorcycle Helmets,

**•** Rear Impact Guards,

**•** Rear Impact Protection.

**•** Windshield Zone Intrusion,

**•** School Bus Rollover Protection, **•** School Bus Body Joint Strength,

**•** Occupant Crash Protection,

**•** Seat Belt Assembly Anchorages,

To determine the crash response, broad amount of tests have been carried out for many years by the validated official agencies for crash worthiness. During the collisions under the combined loading conditions, the application of the crash energy management is dependent to plenty of situations, starting with contact mechanics and collapse modes that could be in the axial and/or in bending way causing many other reactions. According to Huang [5], the crash tests were chosen after reviewing some previous works around the world, accident statistics, and experience with the Ford Tempo air bag fleet based on the real-world crash investigations. The tests consisted of car-to-car tests versus barrier and fixed pole tests. Crash data were accumulated from the 22 vehicles; the chosen tests representing a vast range of accidents at or near the expected threshold of air bag deployment. There are 22 vehicles in 16 tests, as shown in (**Figure 5**), were used to gather the crash pulse data. For every test, the selected impact speed is a key factor to check the system performance of the air bag sensor will be activated or not during the incidents. Due to mentioned circumstances, we can define the types of the impacts [5]:


The tests can be classified in three categories: component tests, sled tests, and full-scale barrier impacts. Because of the complexity and many distinct test variables in full-scale tests, there is an acceptable reason in the reduction of the test's repeatability. The impact test depicted in (**Figure 6**) is representing a full-scale vehicle-to-vehicle impact test of Toyota Motor Company while they are developing a new safety system for their automobiles [18]. The dynamic and/or quasi-static response of an isolated component is defined by the component tests are exalted to detect the crush mode and energy absorbing ability. With the help of the component tests, it also gives the capability to the designers to develop prototype substructures and mathematical models. Moreover, the vehicle rear structure full-scale tests are governed either via a deformable barrier or a bullet car to state the integrity of the fuel tank. To evaluate roof strength according to FMVSS 216, a quasi-static load is applied on the "greenhouse," and providing that the roof deformation falls below a particular level for the applied load [6].

**Figure 6.** Vehicle-to-vehicle impact test of Totoya Motor Company.

For the sled test, engineers use a representation of a passenger compartment (buck) with all or some of the interior parts like seat, front panel, steering system, seat belts, and air bags. Anthropomorphic Test Devices or "Dummies" (ATD) or cadaver subjects are seated in the buck, utilized to simulate an occupant subjected to dynamic loads which is similar to a vehicle deceleration-time pulse, to determine the response in a frontal impact or side impact. To appraise the restraints of the system the sled test is a significant topic recorded by the highspeed cameras and photography applications for the dummy kinematics. It should also be stated that the performance of the ATD is determined at a higher impact speed of 35 mph in the NCAP test. Throughout the NCAP test, the restrain system is composed of three-point lap/ shoulder belt system, and also additional restraint air bag. When we pay attention to the detail of the impact tests, numerous numbers of sensors as accelerometers, load cells, etc., located in the dummy and on the restraints, screen the forces and moments assisting to specify the impact reactions. Event data recorders have a very important role to understand the behavior of the system during accidents. However, when the recorded data will be analyzed digital filtering and reducing the noise (unwanted data) effect the results. Thus, it should be figured out cautiously.

selected impact speed is a key factor to check the system performance of the air bag sensor will be activated or not during the incidents. Due to mentioned circumstances, we can define the

The tests can be classified in three categories: component tests, sled tests, and full-scale barrier impacts. Because of the complexity and many distinct test variables in full-scale tests, there is an acceptable reason in the reduction of the test's repeatability. The impact test depicted in (**Figure 6**) is representing a full-scale vehicle-to-vehicle impact test of Toyota Motor Company while they are developing a new safety system for their automobiles [18]. The dynamic and/or quasi-static response of an isolated component is defined by the component tests are exalted to detect the crush mode and energy absorbing ability. With the help of the component tests, it also gives the capability to the designers to develop prototype substructures and mathematical models. Moreover, the vehicle rear structure full-scale tests are governed either via a deformable barrier or a bullet car to state the integrity of the fuel tank. To evaluate roof strength according to FMVSS 216, a quasi-static load is applied on the "greenhouse," and providing that the roof deformation falls below a particular level for the applied load [6].

**5.** A vehicle front to an moving deformable barrier (MDB) perpendicular,

types of the impacts [5]:

68 Autonomous Vehicle

**1.** A perpendicular (90°) barrier,

**3.** A front-to-front overlap,

**6.** A vehicle front-to-side,

**7.** A front-to-rear,

**2.** A low- and high-speed rigid pole,

**4.** An oblique front to front (three types),

**8.** A bumper over-ride (or truck under-ride).

**Figure 6.** Vehicle-to-vehicle impact test of Totoya Motor Company.

Driving through the highways or freeways, the barriers are limiting the vehicles to get out of the road and protecting it, from crossings. During the barrier impact test there is a guided vehicle, canalized into a barrier with a predetermined initial velocity and angle. The purpose of the test is to maintain a structural integrity of the vehicle and adherence to the mandatory government regulations. The fully equipped vehicle collides a barrier at a 0°, +30°, and −30°, respectively, from an initial velocity of 30 mph.

The frontal offset impact test is another method acting with 40–50% overlap stating that the impact target could be rigid or deformable.

For the full-scale side impact test, a deformable barrier moving towards the left or right side of the vehicle with an initial speed at a certain angle (FMVSS 214). Especially for this test, side impact dummies ("SID" For the US and "EURO SID1" for Europe) which have different shape and properties, are used in the driver and outboard rear seat positions.

When the human parts are considered, the ATDs are widely used and capable enough to demonstrate the behaviors of the human nature in a fundamental way, even when it is indicating the spine, head, brain, organs, knee injuries, and whiplash incident in particular.
