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This standard is drafted in accordance with the rules given in the GB/T 1.1-2009
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This standard was proposed by the China National Light Industry Council.
This standard is under the jurisdiction of SAC/TC 305 (National Technical Committee 305 on Footwear of Standardization Administration of China).
Footwear — Test Methods for Whole Shoe — Impact Shock Attenuating Property
1 Scope
This standard specifies the test methods for impact shock attenuating property of whole shoe and sole.
This standard is applicable to the whole shoe and sole of size 235 and above.
2 Normative References
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 22049-2019 Footwear — Standard Atmospheres for Conditioning and Testing of Footwear and Components for Footwear
3 Terms and Definitions
For the purposes of this document, the following terms and definitions apply.
3.1
shock attenuating
process by which the peak force decreases with time
3.2
energy
the ability to do work and overcome resistance, which is calculated by integrating the force and the displacement produced by the force
Note: The energy in joules (J).
3.3
impact energy
energy applied to the sample during impact shock compression
Note: The energy in joules (J).
3.4
energy return
energy returned during recovery after maximum compression deformation
Note: The energy in joules (J).
3.5
energy absorption
energy lost during the compression cycle
Note: The energy in joules (J).
3.6
energy absorb ratio
percentage of energy absorption (3.5) versus impact energy (3.3).
3.7
energy return ratio
percentage of energy return (3.4) versus impact energy (3.3)
3.8
stiffness
resistance of a material to deformation, expressed as the ratio of the peak force to the peak deformation of the material
Note: The stiffness in N/mm.
4 Principle
The stress and deformation of sole materials in the actual running or walking state of the person can be simulated by loading displacement or force on the test sample, the stiffness and energy changes of the sole in the process of instantaneous compression are tested to evaluate the shock attenuating property of sole.
5 Test Apparatus
5.1 Material tester
5.1.1 Test platform: the area is ≥(500 mm × 500 mm), the center of the platform is aligned with the impact head, and the table is flat and not elastic.
5.1.2 Power device: A power source that capable of driving the impact head to apply force and move a certain distance.
5.1.3 Hammer: It is made of 6061 aluminum alloy, and the hammers simulating the shape of the applied part of foot is used for the forepaw and heel respectively [see Figure 1a) for the shape of the forepaw hammer, and see Figure 1b) for the shape of the heel hammer]. The length × width of the forepaw hammer surface is (85 ± 1) mm × (50 ± 1) mm, and the height of the hammer crown is 5 mm. The heel hammer surface is a circle with a diameter = (50 ± 1)mm, and the height of the hammer crown is 5 mm.
a) Shape of forepaw hammer b) Shape of heel hammer
Figure 1 Shape of impact hammer
5.1.4 The device can achieve the minimum time interval of two impacts of 1 s.
5.1.5 Force sensor: the range is 0 N to 5 000 N, the accuracy is 0.01 N, and the sampling frequency of force sensor is at least 2 500 Hz.
5.1.6 Displacement sensor: the range is 0 mm to 60 mm, the accuracy is 0.01 mm, and the sampling frequency of displacement sensor is at least 2 500 Hz.
5.1.7 Software acquisition system: the program can record the data of time, displacement and force in each impact process, and present the relevant curves of output force-time, displacement-time and force-displacement in the impact process. According to the recorded force value and displacement data, and by using the work integral sum formula [where W is the energy, in joules (J); F is the force value, in newtons (N); ds is the displacement, in millimeters (mm)], the energy of the impact compression process (impact energy), the energy of the impact return process (energy return) can be calculated by the system, and the difference between the two is the energy absorption.
5.1.8 Waveform of impact process: the process of device force can be loaded and unloaded in the form of triangular wave.
5.1.9 Loading and unloading time in the impact process: the forepaw and heel are unified into 25 ms for loading and 40 ms for unloading. Different loading and unloading time can also be defined according to the actual requirements (such as quick start, jumping and landing, etc.).
Foreword II
1 Scope
2 Normative References
4 Principle
5 Test Apparatus
6 Test Sample and Conditioning Environment
7 Test Procedure
8 Test Result
9 Test Report