Codeofchina.com is in charge of this English translation. In case of any doubt about the contents of English translation, the Chinese original shall be considered authoritative.This standard was drafted in accordance with the rules given in GB/T 1.1-2009.
This standard replaces GB/T 3903.1-2008 Footwear—General Test Methods—Flexing Resistance. The following technical deviations have been made with respect to the GB/T 3903.1-2008:
——The standard name is modified;
——The application scope is modified;
——Description for the principle of this standard is modified;
——The sampling quantity is modified;
——The requirements for clamp holder of flexing tester are added;
——Test procedures are modified;
——Description for the test results is modified.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. The issuing body of this document shall not be held responsible for identifying any or all such patent rights.
This standard was proposed by China National Light Industry Council.
This standard is under the jurisdiction of the National Technical Committee 305 on Shoemaking of Standardization Administration of China (SAC/TC 305).
The previous editions of the standard replaced by this standard are as follows:
——GB 3904-1983.
——GB/T 3903.1-1994, GB/T 3903.1-2008.
Footwear—Test Methods for Whole Shoe—Flexing Resistance
1 Scope
This standard specifies test methods for flexing resistance of whole shoe or sole.
This standard is applicable to whole shoes and soles.
This standard is not applicable to whole shoes or soles that have a heel height more than 70mm, a thickness of the sole more than 25mm where it is flexed, or a flexing angle less than 45° after stiffness test as specified in 8.4.1 of GB/T 20991-2007.
Note 1: thickness of the sole where it is flexed includes thickness of the insole.
Note 2: reference may be made to this standard for testing the sole materials (pieces).
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 20991-2007 Personal Protective Equipment—Test Methods for Footwear
GB/T 22049 Footwear - Standard Atmospheres for Conditioning and Testing of Footwear and Components for Footwear
3 Principle
After the flexing test on the flexing tester at specified flexing angle and frequency, whole shoes or soles shall be observed for any changes on the bonded parts of upper surface, sole and upper sole.
4 Apparatus
4.1 Flexing tester
4.1.1 The flexing angle is adjustable between 0°~55°.
4.1.2 The flexing frequency is adjustable between 100 times/min~300 times/min.
4.1.3 Clamp holders shall be capable of fixing the specimens firmly such that any looseness will not occur during the test. Clamp holders shall be adjustable with regard to the inclination angle to ensure that the specimens are under the natural state without flexing in any direction when the tester is at the minimum flexing angle.
4.1.4 The tester shall be equipped with automatic stop function according to preset flexion times.
4.1.5 The tester shall be equipped with blower device for flexing positions of specimens.
4.2 Flexing test last
4.2.1 From the first metatarsophalangeal position of flexing test last to the vertical line of last bottom axes, a steel shaft of φ(5.5±0.5)mm×(40±2)mm is mounted, and relative to the last bottom surface, the steel shaft is free from unevenness.
4.2.2 The maximum flexing angle of flexing test last is not less than 50°.
4.3 Vernier caliper
It is to the nearest of 0.02mm as a minimum.
4.4 Nick cutter
See Figure 1 for the schematic diagram of nick cutter.
Dimensions in millimeters
Figure 1 Nick Cutter
5 Specimens
Each group of specimens shall include at least one pair of whole shoes or soles, and specimens shall be glued for 24h as a minimum.
6 Test Conditions
6.1 The flexing tester has a flexing angle of (50±1)° (0°~55° in special cases).
6.2 The flexing tester has a flexing frequency of (230±10) times/min (100 times/min~300 times/min in special cases).
6.3 According to the requirements of GB/T 22049, tests shall be carried out under the standard environmental temperature (23±2)℃.
7 Test Procedures
7.1 Prior to test, the specimens shall be placed under the standard environmental temperature (23±2)℃ for at least 4h according to the requirements of GB/T 22049.
7.2 The specimens are inspected, and in case of foreign bodies on the surface, they will be wiped up with gauze stained with ethanol.
7.3 The specimens shall be mounted to suitable flexing test lasts (4.2); in general case, the last size should be 5mm less than the footwear size, to prevent the front upper surface from being strained.
Example: if the footwear size of the specimen is 240, a 235 last should be selected.
7.4 Bend the specimens. Mark metatarsophalangeal flexing positions on the edges on both sides of the shoes, and draw a flexing line through the two marked points on the sole.
7.5 The specimens are clamped in the clamp holder of the flexing tester (4.1). The sole flexing line, the steel shaft of flexing test last and the axis of clamp holder sliding shaft shall be located on the same horizontal plane.
7.6 The tester is adjusted at the minimum flexing angle, and the clamp holder shall be adjusted to an inclination angle at which the heelpiece position is observed and the specimens are under the natural state without flexing in any direction.
7.7 The tester shall be such adjusted to an appropriate eccentricity that it reaches the specified flexing angle (6.1).
Foreword i
1 Scope
2 Normative References
3 Principle
4 Apparatus
5 Specimens
6 Test Conditions
7 Test Procedures
8 Test Results
9 Test Report
