Full-load occupant simulation reveals Changan Auchan collision test

　　[car home Safety Technology] For most netizens, the collision test of automobiles is a relatively unfamiliar field. However, the birth of every new car must go through this test about the safety of car owners. Recently, Changan Automobile seems to have fallen in love with the "brush" performance in the crash test, and has also spent a lot of effort on crash safety. Their products from Yidong to CS75 have achieved good results in the domestic crash safety test. From the perspective of Chang ‘an people, of course, they will not be satisfied with the results in the car crash test, so they built an MPV—— with a five-star safety rating standard-Chang ‘an Auchan (hereinafter referred to as Auchan). Because MPV can carry more passengers, it is particularly important to protect the passenger compartment. Before Auchan’s C-NCAP test results were officially announced, I had the honor to visit a 100% frontal crash test of Auchan in Changan Automobile Research Institute.

　　The C-NCAP crash test has experienced the development of three generations of regulations. From the original 2009 version to the current 2015 version, the requirements for "five-star" safety performance are also increasing. Now the latest regulations are more stringent on the basis of the 2012 version. The driver’s seat belt prompt function and ISOFIX function were cancelled, and the total score was reduced from 62 to 61, but the total score and evaluation method for frontal collision remained unchanged, still 18 points.

"Image source: C-NCAP official website"

"Image source: C-NCAP official website"

"Image source: C-NCAP official website"

　　At present, the minimum score of five-star performance has increased from 52 to 54, while the minimum score of four-star performance has increased from 44 to 48, which also puts forward higher requirements for future vehicles.

● Different from the previous full-load collision test.

　　At present, the test of C-NCAP stipulates that Changan Auchan only needs to place four test dummies in the front row and the second row. However, you should know that it is a 7-seat MPV, and there will be a situation full of seven members in actual use. Therefore, the engineers of Chang ‘an Automobile Research Institute heroically stuffed this car with seven test dummies, which simulated the vehicle state when the collision occurred in the real car situation to the maximum extent. In order to ensure the safety of all seven members in the car, the body structure and materials are the first problems that engineers should consider.

　　According to the regulations of C-NCAP, the test of 100% frontal collision is specified in detail, but simply speaking, the so-called 100% frontal collision can be understood as the test that the vehicle collides with a fixed rigid object at a speed of 50 km/h.

　　In the crash test laboratory of Changan Automobile Research Institute, there are more than 300 vehicles used for testing every year. This figure shows that almost every day, an Changan automobile is crashed here with a "duang" for the safety of its owners, so as to exchange a large number of test data related to vehicle safety to improve or improve the safety performance of vehicles.

　　Before the collision, the engineer will install various sensors for the tested vehicle to record all kinds of data fed back when the vehicle collides. Of course, the most important one is the crash test dummy, and the price of the Hybrid III dummy used for the test is as high as one million yuan. Manufacturers can provide adult male, female and child dummies for simulation test. They are not only expensive, but also have strict regulations in the use process, and often need to re-calibrate the parameters after several collision tests, which can be said to be expensive and exquisite.

● Auchan collision test

　　In just a few seconds, the tested vehicle was accelerated to 50km/h in the test site and hit the fixed rigid wall at this speed. This is a very short process, and the rest is a lot of analysis of the impact data by engineers. It can be seen from the pictures on the scene that after the collision, Auchan’s front car has obviously collapsed and absorbed energy, and the length of the engine compartment has changed obviously.

　　Because the specific collision data and results of Auchan are not known at present, we can only make visual observation from the collision vehicles at the scene and make a comprehensive analysis combining with some previously published materials.

　　For the force transmission structure design of the front part of the car body during collision, Auchan added the design of collision dowel bar to the front part of the car body, which can quickly disperse the force acting on the car body during collision and ensure the integrity of the passenger compartment.

　　The design concept of modern automobile is to absorb energy from the engine compartment at the front of the car body as much as possible to ensure the structural integrity of the passenger compartment and the safety of passengers in the car. Therefore, the front position needs to be designed to be "hard and soft": hard means to reduce the damage of the vehicle and reduce the maintenance cost in the future when a low-speed collision does not hurt the occupants in the vehicle; Soft is to sacrifice the space outside the passenger compartment as much as possible to ensure the safety of passengers in case of inevitable serious collision. In order not to deform during collision, the passenger compartment needs to be constructed with very strong materials.

　　Auchan used a lot of high-strength steel as the construction material of the body frame in the design, and the proportion of high-strength steel with yield strength higher than 280 MPa reached 65%. Steel with yield strength higher than 340 MPa was used in the front anti-collision beam, A-pillar, B-pillar reinforcement and rear longitudinal beam, which played a key role in the collision process, to ensure the safety of the passenger compartment.

　　After the collision, Auchan’s front fender was deformed to a certain extent, which had a slight impact on the opening of the front door. Due to the interference of the front fender, the front door needed a little force to open to the maximum angle. However, because the passenger compartment has not been deformed, the doors on both sides can still be opened and closed normally.

　　As for Auchan’s collision test, the manufacturer provided us with pictures taken by high-speed cameras and GIF dynamic pictures, which can show the whole process of the collision and provide help for data analysis after the collision test.

　　Not only the head of the passenger in the car, but also the passenger will move due to inertia in the process of collision. At this time, the only measures to ensure safety to the greatest extent are seat belts and airbags. If you don’t wear seat belts, airbags will pop up and even cause more serious injuries to the passengers during collision. Therefore, it is a very good habit to fasten your seat belt when you get on the bus. The important thing is to say it again: please get into the habit of fastening your seat belt when you get on the bus.

● Changan’s research and development on safety technology.

　　At the technical briefing before the crash test, Changan Automobile Research Institute also introduced several new safety technologies that are being developed and will be applied to Changan Automobile in the near future.

　　According to Zhao Hui, president of Chang ‘an Automobile Research Institute, Chang ‘an is currently developing a new technology of seat belt airbag, which is different from the common seat belt design with airbag on the market at present. Its airbag is placed at the belt position of three-point seat belt. This design can better bind passengers closer to the center of gravity of the human body, prevent them from sliding forward due to inertia when a collision occurs, and play a better protection effect when working with the front airbag.

　　In terms of the safety protection of rear passengers, Changan is at the forefront of China brand. Engineers of Changan Automobile Research Institute are developing the front airbag for rear passengers: this is a technology that integrates the front seat back angle sensor, passenger weight sensor and step-by-step pop-up airbag. It can actively adjust the ejection strength of the airbag according to different body types and the backrest angle of the front seat, and can provide better protection effect for the rear passengers. It is reported that this technology is expected to be put into mass production within 3-5 years.

Editor’s summary:

　　Thanks to the use of collapsible materials and reasonable structural design, Auchan dispersed and absorbed collision energy by collapsing the front engine compartment when a collision occurred. The optimization of the car body structure and the use of high-strength steel can quickly disperse the impact force generated by the collision to all parts of the car body after the collision and ensure the safety of the occupants in the car through the high-strength passenger compartment structure. This design concept is the most mainstream and most reasonable collision safety protection concept at present. As mentioned at the beginning of the article, Changan has obtained or will obtain a five-star safety rating from Yidong to CS75 to Auchan we see today. Behind the achievements is Changan’s great efforts in the safety field, so we are very happy to see a China brand MPV with excellent safety performance. (Photo/Text car home Luo Aoyu)