**Chinese Name:** Test Method for Flexural Strength of Glass Materials
**English Name:** Test Method for Flexure of Glass Material
**Approved by:** State Building Materials Industry Bureau
**Approval Date:** August 22, 1997
**Implementation Date:** January 1, 1998
**Standard Number:** JC/T 676-1997
This standard outlines the procedure for determining the flexural strength of glass and glass-ceramic materials. It is widely used in the construction industry to ensure the quality and performance of these materials under bending stress.
### 1. Scope
This standard specifies a method for measuring the flexural strength of glass and glass-ceramic materials. It is applicable to samples that are rectangular in shape and suitable for three-point bending tests.
### 2. Principle
Under controlled conditions, a sample is subjected to a static three-point bending load until it fractures. The flexural strength is calculated based on the maximum bending stress at the cross-section where the load is applied.
### 3. Equipment
#### 3.1 Testing Machine
- The loading rate must be accurate, with a relative error of no more than ±1%.
- The applied load should fall between 20% and 90% of the machine’s capacity.
- The indenter blade and support must be made of hardened steel with an elastic modulus of at least 200 GPa. The surface roughness of the contact area should not exceed 1.6 μm.
#### 3.2 Measuring Instruments
A vernier caliper or micrometer with a precision of 0.02 mm is required to measure the dimensions of the specimen accurately.
### 4. Specimen
- Each specimen should be 120 mm long, 20 mm wide, and have a thickness equal to the original plate.
- The cross-section corners must be square (90° ± 0.5°).
- The specimens should be free from visible defects such as cracks, chips, or scratches.
- At least 15 specimens per group are required for statistical reliability.
### 5. Test Procedure
- Measure the width and thickness of the middle portion of the specimen using a vernier caliper.
- Adjust the span between the supports to 100 mm.
- Place the specimen on the supports with the cut edge facing up.
- Apply a load at a rate of 5 mm/min until the specimen breaks.
- Ensure the fracture occurs within the central third of the specimen. If not, repeat the test with a new sample.
- After each test, clean the indenter and supports thoroughly to remove any residual glass fragments.
### 6. Calculation of Results
The flexural strength (σ) of each specimen is calculated using the formula:
$$ \sigma = \frac{3PL}{2bd^2} $$
Where:
- $ P $ = Maximum load at fracture (N)
- $ L $ = Span length (mm)
- $ b $ = Width of the specimen (mm)
- $ d $ = Thickness of the specimen (mm)
The standard deviation (S) is calculated using:
$$ S = \sqrt{\frac{1}{n-1} \sum_{i=1}^{n}(x_i - \bar{x})^2} $$
Where:
- $ x_i $ = Flexural strength of each sample
- $ \bar{x} $ = Mean flexural strength
- $ n $ = Number of valid samples
Results should be reported as the mean value and standard deviation, rounded to three significant figures.
### 7. Test Report
The final report should include:
a) Name of the requesting organization
b) Sample name, specifications, and identification number
c) Dimensions of each specimen and the maximum load at break
d) Individual, average, and standard deviation values of flexural strength
e) Model and range of the testing machine used
f) Name of the testing institution and personnel involved
This test method ensures consistent and reliable evaluation of the mechanical properties of glass materials, supporting quality control and material selection in various applications.
Bath Mirror,Bathroom Mirror
SHANDONG TOP LEADER GLASS CO.,LTD , https://www.topleaderglass.com