Evaluation method for dynamic crack propagation index of glass materials

Abstract

This invention discloses a method for evaluating the dynamic crack propagation index of glass materials, comprising: firstly, artificially constructing defects on the glass surface to establish a load-crack initiation probability relationship, thereby determining the optimal load for the pre-fabricated defects to prepare controllable pre-fabricated defects on the glass sample surface; subsequently, annealing the sample, and then using a coaxial double-ring test to test the bending strength ( ) under different stress loading rates, and combining Weibull statistical analysis to obtain the characteristic strength ( ); finally, performing linear fitting based on a double logarithmic relationship to accurately calculate the value. This invention effectively solves the problems of inappropriate pre-fabricated defect load, residual stress interference, and large systematic errors in reported traditional testing methods. It can accurately determine the optimal load for the pre-fabricated defects, resulting in high accuracy and repeatability of the obtained dynamic crack propagation index test results, and has a significant accuracy advantage over traditional methods, overcoming the problems of large errors in existing testing methods.

Description

Technical Field

[0001] This invention belongs to the technical field of glass material performance testing, specifically relating to a method for evaluating the dynamic crack propagation index of glass materials. Background Technology

[0002] Glass, due to its excellent light transmittance, chemical stability, and processability, is widely used in construction, electronics, optics, aerospace, and other fields. During actual service, glass is often subjected to dynamic loads such as impact, vibration, particle collision, and thermal stress waves, leading to crack defects. The propagation behavior of these crack tips determines the glass component's resistance to damage and its safety in use. Therefore, accurately characterizing the mechanical parameters that represent the resistance to crack propagation in glass under dynamic loads is of great significance for material performance research and engineering applications. Among these parameters, the dynamic crack propagation index... It is an important indicator used to characterize the sensitivity of crack propagation rate of brittle materials to external load driving force, and has been proven to be a key parameter in the reliability design and life prediction of glass dynamic fracture.

[0003] However, currently, there is a lack of understanding of glass materials. There is currently no standardized testing method for obtaining the value. Based on search results from databases such as the Web of Science, regarding... Existing research on soda-lime silicate glass is limited. This is because the simple composition, mature manufacturing process, and low cost of this type of glass allow researchers to conduct extensive exploratory work before the theoretical framework and experimental methods are fully unified, and then extend the research to more expensive or more complex specialty glasses once the methods are mature. n Analysis of the test conditions and results (see Table 1) reveals significant differences in existing studies regarding sample preparation and loading strategies, leading to discrepancies in the reported values. The value fluctuated significantly between 10 and 35, causing The test results exhibit high dispersion and poor comparability. The main factors contributing to these problems include:

[0004] (1) Inconsistent prefabrication defects: Different studies used various methods such as inherent defects of the original sheet, sandpaper abrasion, scratches, and Vickers indentation, and the prefabrication defect loads were inconsistent, resulting in significant differences in crack morphology, initial crack depth, and residual stress field; and the differences in prefabrication defects had a significant impact on the overall crack morphology, initial crack depth, and residual stress field. The mechanism by which the value is affected has not been reported;

[0005] (2) Inconsistent annealing treatment: Whether annealing is performed after prefabrication of defects and the difference in annealing process will lead to significant differences in residual stress level, which directly affects the effective stress intensity factor at the crack tip, and thus affects Value test; and residual stress on The mechanism by which the value is affected remains unclear;

[0006] (3) The loading methods are significantly different: three-point bending, four-point bending, coaxial double ring, etc. are all used, and their stress field distributions are different, making it difficult to establish an equivalent relationship between the results of different literature.

[0007] It is particularly important to point out that it is precisely because of the... Regarding the current state of research on crack propagation index determination, there are currently no unified international standards or specifications on "how to determine the pre-existing defect load?" and "how to standardize the test procedure?". Different studies often set the indenter load based on experience or subjective judgment, leading to uncontrollable crack depth and crack morphology. The differences in the initial crack state may even exceed the inherent differences between different material systems. Given the dynamic crack propagation index... The test results are highly sensitive to the initial crack size and the stress state at the tip. The non-standardization of this step is one of the core reasons for the high dispersion and lack of repeatability of the test results.

[0008] In summary, existing glass materials Existing methods for evaluating the dynamic crack propagation index of glass materials generally suffer from problems such as inconsistent procedures, uncontrollable defect pre-fabrication, inconsistent residual stress treatment, and insufficient repeatability, making it difficult to meet the requirements of engineering applications for data accuracy, reliability, and comparability. Therefore, there is an urgent need for a method for evaluating the dynamic crack propagation index of glass materials that features reasonable pre-fabrication defects, standardized testing procedures, accurate test results, and high repeatability, in order to effectively overcome the shortcomings of existing technologies.

[0009] Table 1. Sodium-calcium silicate glass in the literature Summary of test conditions and results for the value

[0010] Summary of the Invention

[0011] The purpose of this invention is to address the shortcomings of existing technologies by providing a method for evaluating the dynamic crack propagation index of glass materials. This method scientifically determines the optimal load for pre-fabricated defects, ensuring the consistency and rationality of crack initiation, and thus improving the obtained dynamic crack propagation index. The test results are accurate (relative standard deviation ≤10%) and highly repeatable, and have a significant accuracy advantage over traditional methods, overcoming the problems of large errors in existing test methods.

[0012] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0013] A method for evaluating the dynamic crack propagation index of glass materials includes the following steps:

[0014] Step 1: Obtain the glass sample to be tested and pre-treat it;

[0015] Step 2: Apply different loads to the pretreated glass samples to obtain cracks with an initiation probability of 0%-100%. Based on this, establish the relationship between load and crack initiation probability. Then, determine the optimal load for prefabricating defects according to the relationship. Use the optimal load to prefabricate defects on new glass samples to obtain multiple test specimens.

[0016] Step 3: Anneal the multiple test samples;

[0017] Step 4: Using the undefected surface of the annealed test specimen as the loading surface, conduct coaxial double-ring tests on different test specimens under different stresses and loading rates. Test multiple test specimens at each stress loading rate and record the failure load of each test specimen. ;

[0018] Step 5: Inspect the fracture condition of the specimen, retain the valid test specimens, and determine the fracture load based on the valid test specimens. Calculate its corresponding stress loading rate Bending strength And calculate its fracture probability. Then construct based on this – The relationship is used to obtain the stress loading rate for each stress. Characteristic bending strength ;

[0019] Step 6: Construct the stress loading rate Its corresponding characteristic bending strength The relationship between the two is used to calculate the dynamic crack propagation index. .

[0020] Furthermore, in step 2, the Weibull cumulative distribution function is used to perform curve fitting on the load and crack initiation probability to obtain the relationship between the two.

[0021] Furthermore, in step 2, based on the relationship between load and crack initiation probability, the load corresponding to a crack initiation probability of 50-100% is selected as the optimal load.

[0022] Furthermore, the method for preparing cracks in step 2 is as follows: multiple indentations are prepared using a hardness tester under different loads, the distance between adjacent indentations is not less than 5 times the length of the diagonal of the indentation, the indentation holding time is not less than 10 seconds, and after unloading, the indentation is left to stand for more than 60 seconds to count the number of indentation angles that produce radial cracks and calculate the crack initiation probability.

[0023] Furthermore, the annealing method in step 3 is as follows: heating the test specimen after the pre-formed defect to the glass transition temperature. Tg Insulate it with heat, then cool it to room temperature.

[0024] Furthermore, the annealing heating rate is 5-10. The cooling rate is 2-5 .

[0025] Furthermore, before loading in step 4, a thin film is attached to the loading surface of the test specimen. After the test specimen breaks, the broken fragments are collected through the thin film, the morphology of the fragments is observed and the location of the fracture origin is located. Test specimens whose fracture origin deviates from the pre-made defect are discarded, and test specimens whose fracture origin is located at the pre-made defect are retained as valid test specimens.

[0026] Furthermore, in step 5, based on the fracture load... Calculate bending strength The method is as follows:

[0027]

[0028] in, The Poisson's ratio of the sample. These correspond to the thickness and side length of the test specimen, respectively. , These correspond to the radii of the loading ring and the support ring, respectively.

[0029] The bending strength of the coaxial double ring is calculated based on the above formula. .

[0030] Further, in step 5, according to each stress loading rate The following calculations yielded multiple bending strengths and the corresponding fracture probability ,draw – A relationship diagram was plotted, and the Weibull cumulative distribution function was used to fit the relationship between the two. The fitted curve... corresponding That is, the characteristic bending strength under the corresponding stress loading rate. .

[0031] Furthermore, the method for calculating the dynamic crack propagation index in step 6 is as follows:

[0032] draw A double logarithmic coordinate graph, according to the formula Perform linear regression fitting, where, The slope of the linear equation is obtained by fitting the constant using the least squares method. According to the slope Calculate the dynamic crack propagation index .

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] 1) Reasonable determination of the optimal load for prefabricated defects: This invention scientifically determines the load for prefabricated defects based on the relationship between "load and crack initiation probability," thereby enabling precise control of the load magnitude and consistency, effectively avoiding the following two problems: First, if the prefabricated defect load is too small, the fracture origin may still be affected by inherent micro-defects in the glass, leading to random crack initiation locations; Second, if the prefabricated defect load is too large, it will cause additional damage below the indentation (e.g., Figure 12 As shown), this additional damage cannot be eliminated by annealing and will introduce an unpredictable stress field, causing the measured... The values ​​deviate irregularly; this invention ensures the consistency of crack origin by precisely controlling the morphology of pre-fabricated defects, thereby guaranteeing that the test results can reliably characterize the intrinsic properties of the material.

[0035] 2) The testing method is accurate and the systematic error is small:

[0036] a. Annealing eliminates residual stress from the indentation, ensuring that test results reflect the intrinsic properties of the glass; Vickers indentation creates a densification zone on the glass surface and introduces residual stress, which generates an additional stress intensity factor at the crack tip. , and the external load generated Superposition makes the actual effective stress intensity factor become = During the subcritical crack propagation stage ( <1, For fracture toughness), the crack propagation rate satisfies:

[0037]

[0038] This represents the critical crack propagation rate at fracture. Because... > Actual measurement of unannealed samples The value must be greater than the intrinsic value of glass. The value cannot represent the intrinsic crack propagation behavior of the material;

[0039] b. The coaxial double-ring loading mode provides high linearity of the load-displacement curve, allowing for direct strength calculation via formulas. Furthermore, rubber pads compensate for specimen flatness deviations, and a centering device ensures accurate alignment, effectively reducing systematic errors during testing. In contrast, three-point / four-point bending is prone to large deflection deformation, leading to nonlinearity in the load-displacement curve (see...). Figure 4 and Figure 5 Additional corrections are required, introducing uncertainty.

[0040] c. Multiple specimens were tested at each stress loading rate, and their characteristic strengths were obtained by Weibull statistical analysis. The relative standard deviation of the results was ≤10%, which significantly improved the statistical reliability of the results.

[0041] 3) The operation process is efficient and widely applicable: The process of this invention is clear, the parameters are controllable, and the repeatability is high. The required equipment (Vickers hardness tester, coaxial double ring tester, muffle furnace, etc.) are all conventional experimental equipment and are easy to obtain. The method is applicable to various oxide glasses, and the pre-made defect load and annealing parameters can be adjusted according to the characteristics of different glasses, which has good promotion and application value. Attached Figure Description

[0042] Figure 1 This is a process diagram illustrating the load-crack initiation probability relationship obtained in an embodiment of the present invention.

[0043] Figure 2 This is a graph showing the load-crack initiation probability fitting relationship in an embodiment of the present invention.

[0044] Figure 3 This is a load-crack initiation probability diagram of the soda-lime silicate glass in Example 1 of the present invention;

[0045] Figure 4 The load-displacement curves of the coaxial double-ring test of the sodium-calcium silicate glass sample under different load loading rates in Example 1 of this invention are shown.

[0046] Figure 5 This is the load-displacement curve of a four-point bending test of sodium-calcium silicate glass after prefabrication and annealing in Example 1 of the present invention;

[0047] Figure 6 This describes the typical breakage mode and origin point of the sample in the coaxial double-ring test of Example 1 of the present invention;

[0048] Figure 7 Weibull statistical analysis was used to determine the feature intensity in Example 1 of this invention. Schematic diagram;

[0049] Figure 8 Sodium-calcium silicate glass, Example 1 of the present invention. The effect of annealing versus non-annealing treatment in value testing;

[0050] Figure 9 This is a load-crack initiation probability diagram of lithium aluminum silicate glass in Example 2 of the present invention;

[0051] Figure 10 The load-displacement curves of the lithium aluminum silicate glass sample under different load rates in the coaxial double-ring test of Example 2 of the present invention are shown.

[0052] Figure 11The characteristic strength of the coaxial double ring of the lithium aluminum silicate glass sample in Example 2 of this invention. With stress loading rate The logarithmic relation;

[0053] Figure 12 The images show the indentation cross-sectional morphology of sodium-calcium silicate and lithium-aluminum silicate glasses under different loads in embodiments of the present invention. Detailed Implementation

[0054] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0055] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0056] The present invention will be further described below with reference to specific embodiments, but these are not intended to limit the scope of the invention.

[0057] Example 1

[0058] A method for evaluating the dynamic crack propagation index of glass materials includes the following steps:

[0059] 1) Sample preparation: Select a sodium-calcium silicate glass substrate, preferably processed into a substrate with a side length of [missing information]. = 100±2 mm, thickness = 3±0.5 mm square specimen, corresponding to the contact radius of the loading ring = 9±0.1 mm, contact radius of support ring =45±0.1 mm, surface polished to a roughness of less than 0.1 μm rms; for float glass, either the tin side or the air side is uniformly selected as the stress surface for the double-ring test to ensure the accuracy of experimental data and the consistency of results;

[0060] 2) Pre-fabrication defects: The sample was prepared using the float glass process. At least 20 indentations were made on the air surface using a Vickers hardness tester under a selected load. The distance between adjacent indentations was not less than 5 times the diagonal length of the indentation (to prevent the influence of existing indentations on the intrinsic properties of the glass). The indentation holding time was 15 s. After unloading, the sample was allowed to stand for at least 60 s. The number of indentation angles that produced radial cracks was counted, and the crack initiation probability was calculated as (number of angles producing radial cracks / total number of indentation angles × 100%). See [reference needed]. Figure 1By gradually increasing the indentation load, the crack initiation probability was increased from 0% to 100%. A load-crack initiation probability graph was plotted. The graph was then fitted with the Weibull cumulative distribution function to obtain a curve relationship between the load and the crack initiation probability. Based on this curve relationship, the load corresponding to a crack initiation probability of 50-100% was selected as the optimal load for the prefabricated defect. Figure 2 As shown. In this embodiment, the loads corresponding to a crack initiation probability of 50% and 100% are 1.16 N and 2.94 N, respectively. Figure 3 ; 2.94 N was selected as the optimal load, and defects were prefabricated again at the center of multiple test specimens to prepare prefabricated defects with strong consistency and appropriate force on the surface of glass specimens. After standing for 24 h, multiple test specimens were obtained.

[0061] 3) Annealing treatment: The test specimen with pre-fabricated defects is placed in a muffle furnace and heated to 530°C at a rate of 5°C / min (the specimen... Keep warm at ≈ 550°C for 2 hours, then cool to room temperature at 2°C / min. Attach an adhesive film to the unprefabricated defect surface to fix the fracture fragments, facilitating subsequent location of the fracture origin.

[0062] 4) Coaxial double-ring test:

[0063] Test environment: Temperature 24±1°C, relative humidity 45%±2%;

[0064] Dimensional measurement: Measure the side length of each sample using vernier calipers. and thickness Accurate to 0.02 mm, used for subsequent calculations;

[0065] Fixture Installation: Install the test specimen, using the unprefabricated defect surface as the loading surface. Based on the actual universal testing machine used, select no fewer than three stress loading rates within the testing range for testing. For each stress loading rate, the number of specimens should be no fewer than 30, and the corresponding test specimen failure load should be recorded. In this embodiment, according to the load-stress conversion formula, the load loading rates corresponding to stress loading rates of 1, 3, 10, 32, and 100 MPa / s are 8.63 N / s, 25.88 N / s, 86.27 N / s, 276.05 N / s, and 862.67 N / s, respectively. Tests were conducted at these load loading rates, with 30 samples tested at each rate, and the values ​​of each sample were recorded. A load-displacement curve was obtained for each load application rate, see below. Figure 4To demonstrate that the load-displacement curve obtained by the coaxial double-ring loading mode has high linearity and can effectively reduce systematic errors during the testing process, this embodiment also uses a three-point / four-point bending test method after performing the same treatment on the test specimen as described above, and obtains its load-displacement curve, see [link to relevant documentation]. Figure 5 .from Figure 5 As can be seen from the data, compared with the coaxial double-ring test, the three-point / four-point bending test method is prone to large deflection deformation, resulting in nonlinearity of the load-displacement curve, which requires additional correction, thus introducing uncertainty and causing unnecessary errors in the test results;

[0066] 5) Data Processing: After the test specimen is broken, fracture fragments are collected using an adhesive film. The morphology of the fragments is observed using an optical microscope to locate the fracture origin. If the fracture origin is located at a pre-fabricated defect, the data for that specimen is valid and retained. If the fracture origin deviates from the pre-fabricated defect (e.g., originating from the edge of the specimen or other scratches), the test data is invalid, must be discarded, and a new test must be conducted. Typical fracture modes and origin points of the test specimens are described in [link to relevant documentation]. Figure 6 ;

[0067] Then based on the measured Calculate the bending strength of a coaxial double ring The formula is:

[0068]

[0069] in, The Poisson's ratio of the sample. These correspond to the thickness and side length of the test specimen, respectively. , These correspond to the radii of the loading ring and the support ring, respectively.

[0070] Based on the above formula and fracture load The bending strength of the coaxial double ring was calculated. .

[0071] Each stress loading rate Obtained from multiple measurements and calculations Sort in ascending order, according to serial number. and total number of samples Calculate the corresponding fracture probability = The results are shown in Table 2;

[0072] Table 2. Same stress loading rate Measured Ascending order and corresponding fracture probability

[0073]

[0074] Based on the data in Table 2, draw... – The relationship diagram was plotted and fitted using the Weibull cumulative distribution function to obtain... – The relationship between the curves is shown in the figure. Figure 7 :

[0075]

[0076] In the formula, Characteristic intensity; The shape parameter characterizes the intensity dispersion. The larger the value, the smaller the dispersion.

[0077] In this embodiment, the result is obtained from the fitted curve. = 63.2% corresponding This is the characteristic bending strength at this stress loading rate. (See Figure 7 ).

[0078] Refer to the data in Table 2 and Figure 7 Weibull statistical analysis was performed to obtain the characteristic strengths at various stress loading rates. Listed in Table 3.

[0079] Table 3. Stress loading rates not required for sodium-calcium silicate glass samples Coaxial double-ring characteristic intensity

[0080]

[0081] Based on the data in Table 3, draw... Image, as shown Figure 8 As shown, then according to the formula (in Linear regression fitting is performed using a constant (e.g., a fitting constant). In this embodiment, the slope of the linear equation is obtained by fitting using the least squares method. The slope calculated in this embodiment = 0.0603 ( >0.99), ensuring the reliability of the fitting results; finally, based on the slope The dynamic crack propagation index was calculated. = (1 / 0.0603) 1 ≈ 16.

[0082] To illustrate the effect of annealing on the dynamic crack propagation index To mitigate the impact of the above-described method, this embodiment also employs the same method to measure and calculate the dynamic crack propagation index of the unannealed test specimen, obtaining the following results: Figure 8The result in the middle. By Figure 8 It can be seen that the indentation-induced residual stress field is still retained in the unannealed specimen after the pre-fabrication defect, and this residual stress introduces an additional stress intensity factor at the crack tip. and generate with external load The superposition of stress intensity factors. Because the effective stress intensity factor at the crack tip is amplified by the residual stress in the sample, the resulting... As the value increases, it can no longer reflect the intrinsic resistance to subcritical crack propagation of the material, thus rendering the measurement results meaningless.

[0083] Example 2

[0084] A method for evaluating the dynamic crack propagation index of glass materials includes the following steps:

[0085] 1) Sample preparation: Select a 3 mm thick lithium aluminum silicate glass substrate (fully annealed, without tempering treatment) and process it into a 100×100×3 mm shape. 3 The square sample, with a surface polished to a roughness of less than 0.1 μm rms, corresponds to the contact radius of the loading ring. = 9±0.1 mm, contact radius of support ring = 45±0.1 mm.

[0086] 2) Pre-fabrication defects: The sample was prepared using the float glass process. At least 20 indentations were made on the air surface using a Vickers hardness tester under a selected load. The indentation holding time was 15 s. After unloading, the sample was allowed to stand for at least 60 s. The number of indentation angles that produced radial cracks was counted, and the crack initiation probability (the ratio of the number of angles producing radial cracks to the total number of indentation angles) was calculated. By gradually increasing the indentation load, the crack initiation probability was gradually increased from 0% to 100%. A load-crack initiation probability graph was plotted. The graph was then fitted using the Weibull cumulative distribution function to obtain the curve relationship between load and crack initiation probability. Based on this curve relationship, the load corresponding to a crack initiation probability of 50-100% was selected as the optimal load for the pre-fabrication defect. In this embodiment, the loads corresponding to crack initiation probabilities of 50% and 100% were 5.2 N and 19.6 N, respectively (see...). Figure 9 Since 19.6 N would cause excessive damage, a smaller load of 9.8 N was selected as the optimal load for pre-fabricating the defect. The defect was pre-fabricated at the center of the test specimen using the optimal load and left to stand for 24 hours.

[0087] 3) Annealing treatment: The pre-made defective sample is placed in a muffle furnace and heated to 520°C at a rate of 10°C / min (the sample... Keep warm at ≈540°C for 2 hours, then cool to room temperature at 5°C / min, and then stick an adhesive film on the surface without pre-made defects.

[0088] 4) Coaxial double-ring test:

[0089] Test environment: Temperature 22±1°C, relative humidity 50%±2%;

[0090] Dimensional measurement: Measure the side length of each sample using vernier calipers. and thickness Accurate to 0.02 mm, used for subsequent calculations;

[0091] Fixture Installation: Install the test specimen, using the unprefabricated defect surface as the loading surface. Based on the actual universal testing machine used, select no fewer than three stress loading rates within the testing range for testing. For each stress loading rate, the number of specimens should be no fewer than 30, and the corresponding test specimen failure load should be recorded. According to the load-stress conversion formula, the load loading rates corresponding to stress loading rates of 1, 3, 10, 32, and 100 MPa / s are 8.63 N / s, 25.88 N / s, 86.27 N / s, 276.05 N / s, and 862.67 N / s, respectively. The "load control mode" was selected for the test.

[0092] Load application: 30 specimens were tested at each loading rate, and the results were recorded. After the test specimen fractured, the fracture fragments were collected using an adhesive film, and their morphology was observed using an optical microscope to locate the fracture origin. Test specimens with fracture origins located at the prefabricated defect were retained, while those with fracture origins deviating from the prefabricated defect were discarded. In this embodiment, it was found that the fracture origins of all test specimens were located at the prefabricated defect, and all data were valid. A load-displacement curve was obtained at each rate, as shown in the figure. Figure 10 .

[0093] 5) Data processing: Calculate the stress loading rate according to the method in Example 1. Coaxial double ring bending strength The feature strength was obtained by performing Weibull statistical analysis. Listed in Table 4.

[0094] Table 4. Stress loading rates not required for lithium aluminosilicate glass specimens Coaxial double-ring characteristic intensity

[0095]

[0096] draw Image, as shown Figure 11 As shown, the slope of the linear equation is obtained by fitting using the least squares method. The slope calculated in this embodiment = 0.0219, >0.97. Finally, based on the slope The dynamic crack propagation index was calculated. = (1 / 0.0219) 1 ≈ 45.

[0097] The above are merely preferred embodiments of the present invention and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should recognize that any equivalent substitutions and obvious changes made based on the content of this specification should be included within the protection scope of the present invention.

Claims

1. A method for evaluating the dynamic crack propagation index of glass materials, characterized in that, Includes the following steps: Step 1: Obtain the glass sample to be tested and pre-treat it; Step 2: Apply different loads to the pretreated glass samples to obtain cracks with an initiation probability of 0-100%. Based on this, establish the relationship between load and crack initiation probability. Then, determine the optimal load for prefabricating defects according to the relationship. Use the optimal load to prefabricate defects on new glass samples to obtain multiple test specimens. Step 3: Anneal the multiple test samples; Step 4: Using the undefected surface of the annealed test specimen as the loading surface, conduct coaxial double-ring tests on different test specimens under different stresses and loading rates. Test multiple test specimens at each stress loading rate and record the fracture load of each test specimen. ; Step 5: Inspect the fracture condition of the specimen, retain the valid test specimens, and determine the fracture load based on the valid test specimens. Calculate its corresponding stress loading rate Bending strength And calculate its fracture probability. Then construct based on this – The relationship is used to obtain the stress loading rate for each stress. Characteristic bending strength ; Step 6: Construct the stress loading rate Its corresponding characteristic bending strength The relationship between the two is used to calculate the dynamic crack propagation index. ; In step 2, based on the relationship between load and crack initiation probability, the load corresponding to a crack initiation probability of 50-100% is selected as the optimal load.

2. The method for evaluating the dynamic crack propagation index of glass materials according to claim 1, characterized in that, In step 2, the Weibull cumulative distribution function is used to perform curve fitting on the load and crack initiation probability to obtain the relationship between the two.

3. The method for evaluating the dynamic crack propagation index of glass materials according to claim 1, characterized in that, The method for preparing cracks in step 2 is as follows: Use a hardness tester to prepare multiple indentations under different loads. The distance between adjacent indentations should not be less than 5 times the length of the diagonal of the indentation. The indentation holding time should not be less than 10 seconds. After unloading, let it stand for more than 60 seconds to count the number of indentation angles that produce radial cracks and calculate the probability of crack initiation.

4. The method for evaluating the dynamic crack propagation index of glass materials according to claim 1, characterized in that, The annealing method in step 3 is as follows: heat the test sample after the pre-made defect to the glass transition temperature, hold it at that temperature, and then cool it to room temperature.

5. The method for evaluating the dynamic crack propagation index of glass materials according to claim 4, characterized in that, The annealing heating rate is 5-10 The cooling rate is 2-5 .

6. The method for evaluating the dynamic crack propagation index of glass materials according to claim 1, characterized in that, Before loading in step 4, a thin film is attached to the loading surface of the test specimen. After the test specimen breaks, the broken fragments are collected through the thin film, the morphology of the fragments is observed and the location of the fracture origin is located. Test specimens whose fracture origin deviates from the pre-made defect are discarded, and test specimens whose fracture origin is located at the pre-made defect are retained as valid test specimens.

7. The method for evaluating the dynamic crack propagation index of glass materials according to claim 1, characterized in that, In step 5, based on the fracture load Calculate bending strength The method is as follows: in, The Poisson's ratio of the sample. These correspond to the thickness and side length of the test specimen, respectively. , These correspond to the radii of the loading ring and the support ring, respectively. The bending strength of the coaxial double ring is calculated based on the above formula. .

8. The method for evaluating the dynamic crack propagation index of glass materials according to claim 1, characterized in that, In step 5, according to each stress loading rate The following calculations yielded multiple bending strengths and the corresponding fracture probability ,draw – A relationship diagram was plotted, and the Weibull cumulative distribution function was used to fit the relationship between the two. The fitted curve... corresponding That is, the characteristic bending strength under the corresponding stress loading rate. .

9. The method for evaluating the dynamic crack propagation index of glass materials according to claim 1, characterized in that, The method for calculating the dynamic crack propagation index in step 6 is as follows: draw A double logarithmic coordinate graph, according to the formula Perform linear regression fitting, where, The slope of the linear equation is obtained by fitting the constant using the least squares method. According to the slope Calculate the dynamic crack propagation index .

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