With the promotion of weight based charging and overloading control in China, lightweight vehicle models are becoming increasingly popular. Various lightweight trucks that claim to be the lightest in history are constantly stimulating people's attention. I believe many people also have this doubt in their hearts. Has the safety of cars also decreased as they become lighter?
In the fiercely competitive market, some brands also express during promotion that they use all steel cabins with guaranteed safety, while other brands have fiberglass cabins on the roof, similar to paper-based ones, with no guarantee of safety. Like many people who buy cars, tapping the car door and tapping the driver's cab to hear the sound can give a sense of whether a car's safety is reliable. The all steel driver's cab sounds like a guarantee of absolute safety for people. So is fiberglass really as fragile as the dealer claims?
Fiberglass reinforced plastic (FRP) has been widely used as a fiber-reinforced plastic since World War II
Fiberglass reinforced plastic, commonly known as FRP (Fiber Reinforced Plastics), is a type of fiber-reinforced composite plastic. It is a composite material that uses glass fiber and its products (glass cloth, tape, felt, yarn, etc.) as reinforcing materials and synthetic resin as the matrix material.
As early as 1955, Europe began using fiberglass in cars. A fiberglass version was tested on the STM-II body. In 1970, Japan used fiberglass to manufacture car wheel decorative covers. In 1971, Suzuki used fiberglass to manufacture engine covers and fenders. In the 1950s, Britain began using fiberglass to replace the previous steel wood hybrid driver's cab. For example, at that time, models such as the Ford S21 and three wheeled cars had a completely new and no longer rigid overall design style.
Some domestic manufacturers have also done a lot of work in the development of fiberglass body convenience. Long ago, FAW successfully developed fiberglass engine covers and flat head reversible cabins. From the current perspective, fiberglass products are widely used in domestic heavy-duty trucks, such as some long engine covers, bumpers, front covers, driver's cab covers, side skirts, and air deflectors. For example, the most familiar domestic manufacturer of flow deflectors, Dongguan Caiji, is known as Dongguan Caiji Fiberglass Co., Ltd. And some of the luxurious sleeper beds of American long headed trucks that people envy are also made of fiberglass materials.
Lightweight, high-strength, and corrosion-resistant vehicles are widely used
Due to the characteristics of low investment, short production cycle, and strong designability, fiberglass materials are currently widely used in many places on trucks. For example, a few years ago, domestic trucks were mainly long headed and flat headed, and high top models were not common. With the rapid development of domestic highways, it greatly stimulated the development of long-distance transportation, and the demand for high top cab tractors was strong. However, due to the difficulty in designing the overall steel shape of the cab's high top, the cost of mold design was high, and if multiple plates were welded together later, it was easy to rust and leak rain. So fiberglass became the choice of many manufacturers for the driver's cab cover at that time, and to this day, some trucks still use fiberglass material for the driver's cab cover.
Fiberglass materials have the characteristics of lightweight and high strength, with a density ranging from 1.5 to 2.0. Only 1/4-1/5 of carbon steel, even lower than aluminum. Compared to 08F steel, the strength of 2.5mm thick fiberglass is equivalent to that of 1mm thick steel. In addition, fiberglass can flexibly design product structures according to needs, using products with better overall shape and excellent processability. The molding process can be flexibly selected according to the shape, purpose, and quantity of the product. The molding process is simple, can be formed in one go, has good corrosion resistance, and has good resistance to atmospheric, water, and general concentrations of acid, alkali, and salt. So currently, many trucks use fiberglass materials for their front bumpers, front covers, skirts, and air deflectors.
Of course, fiberglass also has its drawbacks. Its elastic modulus is low, only 1/10 of that of steel, which can cause low structural stiffness and easy deformation of the product. It is usually compensated for through thin shell structures, sandwich structures, and reinforcement ribs. Some heavy-duty truck cabins in our country use a fiberglass roof structure with steel cladding to enhance their strength. Like many materials, aging can also occur when exposed to wind and sun, and generally does not affect the effectiveness of use for 3-8 years. In addition, repairing damaged fiberglass materials can be quite troublesome.
Fiberglass has good thermal insulation, but its long-term heat resistance is poor. Fiberglass itself does not burn, but the resin contained in it is flammable. The proportion of resin in fiberglass, the properties of reinforcing fibers, and the weaving form will determine its degree of danger. So general fiberglass cannot be used for a long time at high temperatures. In ordinary traffic accidents, some vehicles with missing driver's cab covers and front covers after a fire are actually burned off.
National standards are not necessarily sufficient to meet the requirements of three experiments
There are not many national standards for the safety of truck cabins. In the GB-26512 national standard document on passenger protection in commercial vehicle cabins released in 2011, there are mainly three experiments for commercial vehicle cabins, namely frontal pendulum impact test, top strength test, and rear wall strength test. Except for the dynamic impact in the pendulum experiment, the other two are all subjected to static loads. Moreover, the document also stipulates that if the manufacturing plant can prove through strength calculations or other aspects of the cab components that the top cover or rear bumper can withstand the conditions of the top strength test and the rear bumper strength test, and there is no deformation that endangers passengers (penetrating into the living space), these two tests can be omitted. In addition, there is no national standard for testing the strength of A-pillars.
Regarding the top of the driver's cab, which is of great concern, the national standard experiment stipulates that the top should be able to withstand a static load equivalent to the maximum axle load of one or more axles in the front of the vehicle, with a maximum of 98kN. The secondary static load should be uniformly applied to all support components of the driver's cab or cabin top structure through appropriately shaped rigid components. For example, if the front axle load of a truck is specified as 6 tons, a corresponding pressure of 59kN needs to be applied to the cab. At this time, although the top of the cab is compressed and deformed, as long as there is no penetration or danger to the passenger living space, it will be considered to meet the national requirements. So using fiberglass as the top of the cab, with its high strength characteristics, it is not difficult to meet national standards. In addition, the top of the cab is not the main impact area in common accidents.
Post time: Apr-23-2024
