ASTM D4632 土工布的抓样法断裂强力及伸长率
Written by Charlie Pryor
- ASTM D4632
The grab test is a tensile test where the central part of the specimen's width is tested to establish the "effective strength" of the fabric. The effective strength is the strength of the material at a specific width when combined with the additional strength of adjacent material. Test specimens are cut in both the machine direction and cross-machine direction, but are expected to have their results calculated separately. Specimens are cut to 101.6 mm x 203.2 mm (4 in x 8 in), with attention to the direction of the fabric.
The specimen is loaded into the grips leaving a 75 mm (3 in) separation between the jaw faces. ASTM D4632 calls for jaw faces that are at least 25.4 mm x 50.8 mm (1 in x 2 in). However, it allows for each grip to include one jaw face that is larger than the other (a modified grab test), which can be helpful in reducing the effects of specimen/jaw face alignment. The test is conducted at a speed of 300 mm/min (12 in/min) with the required results being load at break and total elongation.Testing System
Geotextile testing requires a test system with a data rate capture high enough to measure the failure of individual fabric fibers. Because of this, Instron recommends a high tier 6800 Series test frame, which provides a data acquisition rate of up to 5 kHz and captures data peaks and valleys accurately at up to 2500 or 5000 points per second, respectively. For most geotextiles testing to ASTM D4632, a single column frame such as Instron's 68SC-5 is appropriate, as the loads rarely climb higher than 5 kN. The rapid data capture rate in Bluehill Universal software allows data peaks and valleys to be captured accurately.
ASTM D4632 Test Setup
1. Instron 68SC-5
2. Bluehill Universal Dashboard (2490-696)
3. 2580 Series Load Cell (2580-5kN)
4. 2712 Series Pneumatic Grips (2712-045)
Geotextile materials tend to have coatings that may make them difficult to test without slippage or jaw breaks. Instron’s pneumatic side acting grips provide an easy, repeatable, high throughput gripping solution that allow the user to quickly fine-tune gripping pressure to avoid jaw breaks or slippage. Pneumatic side acting grips also feature Instron’s quick-change technology which allows the jaw faces to be easily changed by hand without requiring tools or pins. Since different geotextiles can require a range of different clamping surfaces, quick-change jaw faces can significantly improve throughput in labs where these materials are common.
Bluehill Universal 软件从头开始构建，旨在提供触摸互动和直观的用户体验。使用诸如预装测试方法、几秒钟内快速测试、增强的数据导出以及 Instron Connect（一种全新功能，可提供与服务的直接通信联系）等功能，发现更简单、更智能的测试。 Bluehill 2 和 Bluehill 3 等以前版本软件的用户可以轻松升级到最新版本的 Bluehill。