In the safety guarantee system for riding motorcycles and electric bicycles, the energy absorption performance test under the GB 811-2022 "Motorcycle and Electric Bicycle Passenger Helmets" standard plays an irreplaceable role. As the core equipment for conducting the collision energy absorption performance test, the working principle of the machine contains profound scientific and technological connotations, which is of great significance for accurately evaluating the safety performance of helmets.
1. Design ideas for simulating real collision scenarios
The primary design goal of the helmet collision energy absorption performance testing machine is to highly simulate the complex scenarios of motorcycle and electric bicycle riders encountering collisions in reality. In actual accidents, the rider's head may collide with various objects at different angles and speeds, and the testing machine must try to reproduce these diverse collision situations as much as possible.
Taking free fall impact as an example, the testing machine uses a specific release device to lift the simulated head shape wearing a helmet to the standard height, and then allows it to fall freely, colliding with anvil blocks of different materials and shapes below. For A1 and A2 helmets, an impact velocity of 6.0m/s (theoretical drop height of 1835mm) may be used to strike the flat steel anvil; The A3 helmet impacts the hemispherical steel anvil at the same speed. Through this setting, simulate the situation where a rider falls while driving at high speed and collides with a flat or hemispherical object such as the ground. For example, using a pendulum device, a side collision scenario can be simulated, where the pendulum swings at a certain initial speed and hits the head shape of the helmet wearing it, in order to test the performance of the helmet under side impact.
2. Energy transfer simulation based on impact dynamics
Starting from professional impact dynamics theory, when the helmet collides with the anvil, a huge impact force will be transmitted to the helmet in a very short time. The testing machine cleverly utilizes this principle to simulate impact forces of different intensities by precisely controlling the parameters of the impact device.
The key components in the impact device, such as the precisely controllable impact head, can impact the helmet at a preset speed and angle. Its speed control accuracy is high, for example, when the specified impact speed is measured within the range of 10mm to 60mm after collision, and is not less than 95% of the theoretical speed. During the impact process, energy is transferred from the impact source (such as a free fall head shape, pendulum, etc.) to the helmet, and the helmet material and its structure begin to absorb and disperse energy. The testing machine simulates different energy levels and impact forms by adjusting the mass and shape of the impact head, as well as parameters such as release height, pendulum length, and initial angle, in order to comprehensively examine the helmet's ability to absorb collision energy under various possible collision conditions.
3. Sensor data acquisition and analysis system
During the entire collision process, in order to obtain key data on the helmet's ability to absorb collision energy, the testing machine is equipped with an advanced sensor data acquisition and analysis system. This system is like the "nervous system" of a testing machine, capable of real-time and accurate perception and recording of various physical quantity changes.
The accelerometer is one of the core components. In the single axis acceleration sensor collision test method, a head shape equipped with a single axis acceleration sensor is used to measure the acceleration transmitted to the head shape in real time at the moment of collision. In the three-axis acceleration sensor collision test method (arbitration method), the three-axis acceleration sensor can capture the acceleration changes of the head shape in the X, Y, and Z directions. These sensors can accurately measure the peak acceleration in a very short period of time, as well as the duration of acceleration exceeding specific thresholds (such as 150g, 200g). By analyzing these data, we can intuitively understand the impact reduction effect of helmets on collision force. For example, according to the GB 811-2022 standard, the peak acceleration of Class A helmets should not exceed 300g, and there are corresponding limitations on the duration of acceleration exceeding 150g. The data collected by sensors can be directly compared with the standard to determine whether the helmet meets the standards.
In addition to acceleration sensors, the testing machine may also be equipped with displacement sensors and other devices to measure the deformation of the helmet during collisions. By analyzing the deformation amount, we can further understand the cushioning performance and structural stability of helmet materials. The data collected by these sensors is processed by signal amplifiers, transmitted to a data acquisition card, and ultimately stored, analyzed, and processed by a computer. Computer software can draw detailed acceleration time curves, deformation time curves, etc., providing intuitive and comprehensive data references for researchers and inspectors to deeply evaluate the performance of helmets in absorbing collision energy.
The collision energy absorption performance testing machine simulates real collision scenarios, implements energy transfer simulation based on impact dynamics principles, and uses advanced sensor data acquisition and analysis systems to provide reliable and accurate testing methods for collision energy absorption performance testing under the GB 811-2022 standard. It plays a key supporting role in ensuring the safety of motorcycle and electric bicycle riding.