Auto parts, the higher the hardness, the better? Not necessarily!

The bumper of a vehicle pursues toughness rather than hardness. I have read an old saying in the book called "too rigid and easy to break, good to be soft and invincible", I think it is very appropriate to describe the function of bumpers. Because of what? The bumper is the easiest part of the body to collide with. If it is too hard and small, it will break or break when touched. This is embarrassing. You have to constantly replace the bumper. But if you make it bigger, the manufacturer will charge you aside. If you install a large metal rod in front of your car, it will cause more serious injuries if it hits the pedestrians. Later research found that adding some toughening agent to the bumper would not be easy to break and break, and also have a certain degree of cushioning when a collision occurs, so as not to cause serious damage. It can be described as a multi-purpose effect. Later, the hardness of the bumper was lowered, and the toughness was greatly enhanced.