**I. Comparative Testing**

**1. Instruments and Equipment**

*   **Bursting Strength Method (Hydraulic/Diaphragm):** Uses a bursting strength tester (with a constant volume increase rate of 100 cm³/min to 500 cm³/min, accuracy ±10%) and a diaphragm.

*   **Ball Bursting Strength Method (Elastic Ball):** Uses a ball bursting strength tester with a descending speed of 10 cm/min to 11 cm/min. The ball diameter is 2 cm, and the inner diameter of the ring clamp is 2.5 cm.

*   **Steel Ball Bursting Strength Method (CRE):** Uses a Constant Rate of Extension (CRE) testing machine with an accuracy not exceeding ±1% of the indicated value. It includes a specimen holder and a spherical push rod assembly. The bursting device consists of a ring clamp (inner diameter 45 ± 0.5 mm) for holding the specimen and a polished steel ball (diameter 38 ± 0.02 mm) as the push rod.

**2. Specimen Conditioning and Test Atmosphere**

*   **Bursting Strength Method:** Specimens must be conditioned and tested in an atmosphere with a temperature of (20 ± 2)°C and relative humidity of (65 ± 2)%.

*   **Ball Bursting Strength Method (Elastic Ball):** Specimens are laid flat at room temperature for 20 hours, then placed for 4 hours in a laboratory atmosphere with a temperature of (20 ± 2)°C and relative humidity of (65 ± 3)% before testing.

*   **Steel Ball Bursting Strength Method:** Pre-conditioning, conditioning, and testing atmospheres shall conform to the requirements of GB 6529, i.e., temperature (20 ± 2)°C and relative humidity (65 ± 4)%.

**3. Test Results**

Eight different fabric samples, varying in type and mass per unit area, were selected. Each sample was tested for bursting strength using the Hydraulic/Diaphragm Method, the Elastic Ball Method, and the CRE Steel Ball Method.

**II. Analysis**

**1. Analysis of Test Results**

From the actual test results, it is evident that the strength values obtained from the Elastic Ball Method are significantly lower than those from the Steel Ball Method, with the former being approximately 50% to 60% of the latter. The primary reason for this is the difference in ball diameter: the steel ball used in the CRE method (38 mm) is larger than the elastic ball (20 mm). When bursting the fabric, the contact area between the steel ball and the specimen is substantially larger. To achieve a comparable bursting pressure, the force required for the Steel Ball Method is significantly higher than that for the Elastic Ball Method.

Comparing the standard strength requirements for bursting in the old and new standards reveals an inconsistency: although the new standard adopts the CRE Steel Ball Method, the specified bursting strength requirements have not been correspondingly increased. Similarly, for standards that have not been updated (e.g., FZ/T 73020-2004), the testing method has shifted from the Elastic Ball Method to the Steel Ball Method, but the required strength values remain unchanged from the original standard. This situation appears unreasonable.

**2. Analysis of Fabric Failure Patterns**

Based on actual test results, for plain knit and pique fabrics, the failure patterns (rupture) caused by all three test methods were similar. Plain knit fabrics exhibited rupture parallel to the fabric length direction (wales), accompanied by significant yarn unravelling in the width direction (courses). Pique fabrics typically failed as a hole, with the primary failure mode being yarn breakage, showing almost no yarn unravelling. Therefore, it can be inferred that the three methods share a similar failure mechanism. According to the "weakest link" theory, when a knitted fabric is subjected to bursting forces, initial failure occurs at the point with the lowest strength. This creates a stress concentration. As the test progresses, in plain knit fabrics, loops around the rupture point tend to unravel transversely, while the rupture extends longitudinally. In pique fabrics, more yarns break, causing the rupture to expand radially.

**III. Conclusion**

Based on the analysis above, the following conclusions can be drawn:

1.  Due to the larger diameter of the steel ball compared to the elastic ball, the bursting strength values obtained using the CRE Steel Ball Method (GB/T 19976-2005) are higher than those from the Elastic Ball Method. Currently, product standards that reference GB/T 19976-2005 for bursting strength often have specified requirements that are notably low. Consequently, some products that meet the standard may still have inadequate bursting strength, affecting their performance during use. Therefore, it is recommended that when these standards are revised, consideration should be given to appropriately raising the minimum requirements for bursting strength.

2.  The three test methods exhibit similar failure mechanisms, and the resulting rupture patterns in the fabrics are largely comparable.

3.  The results obtained from the three test methods show a good linear correlation with each other, indicating a strong interrelationship.

一、对比测试

1、仪器设备
胀破法：胀破仪（恒定体积增长速率为100cm3/min~500cm3/min，精度±10%），膜片。
弹子顶破强力试验：弹子顶破强力机，下降速度为10cm/min~11cm/min，弹子直径为2 cm，圆环内径为2.5 cm。
钢球法顶破强力试验：等速伸长型试验仪（CRE），精度不超过示值的±1%。包括一个试样夹持器和一个球形顶杆组件。顶破装置由夹持试样的环形夹持器和钢质球形顶杆组成。环形夹持器内径为（45±0.5）mm，顶杆的头端为抛光钢球，本试验所用钢球直径为（38±0.02）mm。
2、试样处理和测试的环境
胀破法：样品须在温度（20±2）℃和湿度（65±2）%的状态下调湿和试验。
弹子顶破强力试验：将试样在常温下展开平放20 h，然后在试验室温度为（20±2）℃，相对湿度为（65±3）%条件下，放置4 h后进行试验。
钢球法顶破强力试验：预调湿、调湿和试验用大气应按GB 6529规定执行，温度为（20±2）℃，湿度为（65±4）%。
3、测试结果
根据织物的种类和克重选择8种不同的样品，将所选样品按照胀破法、弹子顶破法和钢球法分别测试其顶破强力或胀破强力。

二、分析

1、试验结果分析
从实际测试结果可以看出，弹子顶破法测出的强力值明显小于钢球法，前者大约为后者的50%~60%。这主要是因为：钢球的直径（38 mm）大于弹子的直径（20 mm），织物受顶破作用时，钢球与试样的接触面积明显大于弹子，要达到相同的压强值，钢球法所须加载的力要明显大于弹子顶破法。
对比新、旧标准的顶破强力的标准值可以发现：虽然新标准采用了钢球法测试顶破强力，但是对顶破强力的要求并没有相应的提高；而对于没有更新的标准（如FZ/T 73020-2004等），原来采用弹子顶破法测试针织物的顶破强力，现在均采用了钢球法测试，但是其对顶破强力的要求仍然沿用原标准的标准值，这些显然都是不合理的。
2、破坏分析
（1）为胀破法，（2）为钢球法，（3）为弹子顶破法。
从实际测试结果可以得出，对于平纹组织和珠地组织，三种测试方法所形成的破坏裂口都是相似的。平纹组织会形成平行于织物纵向的裂口，而且沿着织物的横向有较多的线圈脱散；而珠地组织的破坏裂口为破洞形状，破坏主要表现为纱线的断裂，几乎不会形成线圈脱散。因此推断，三种方法具有相似的破坏机理。由弱环理论可知：针织物在受到顶破或胀破作用时，会在某一强力最弱处首先产生破坏，进而在此破坏处产生应力集，随着试验地进行，平纹织物在破坏的周围会有大量的线圈沿横向脱散，裂口沿纵向不断扩展；珠地织物则会有更多的纱线发生断裂，其裂口会沿四周扩展。


三、结言

由以上分析可以得出如下结论：
1）钢球的直径比弹子大，钢球法获得的顶破强力也较弹子顶破法大。目前采用GB/T 19976-2005（钢球法）标准测试顶破强力的产品标准，顶破强力要求明显偏低，使有些产品虽然达到标准要求，但顶破强力值较低，影响服用功能的要求。因此，建议在修订标准时，可以考虑适当提高顶破强力的标准值要求。
2）三种测试方法具有相似的破坏机理，织物破坏后的裂口形状也基本相同。
3）三种测试方法的结果相互之间具有良好的线性关系，三者之间具有很好的相关性