Standardized Methodology for Measuring Bursting Strength of Knitted Fabrics Using James Heal TruBurst Tester (ISO 13935-2:1991)

Abstract

Bursting strength is a fundamental mechanical property for assessing the durability and dimensional resilience of knitted fabrics under multi-directional stress. This study outlines a standardized experimental methodology for evaluating the bursting strength of two commonly used knitted fabric types—100% cotton and 95% cotton with 5% spandex—using the James Heal TruBurst testing system. The procedure complies with ISO 13935-2:1991, and key parameters such as pressure, distension, and time to rupture are systematically recorded to evaluate fabric performance.

1. Introduction

Knitted fabrics, due to their looped structure, are more susceptible to multi-directional stresses compared to woven counterparts. The ability of these fabrics to resist rupture under such stress is critical in determining their suitability for apparel and technical textile applications. This study utilizes the James Heal TruBurst Tester, following the ISO 13935-2:1991 standard, to measure the bursting strength of knitted fabrics. The experiment compares performance across two fabric compositions—pure cotton and cotton-spandex blends—commonly used in garments requiring varying levels of stretch and recovery.

2. Objective

To evaluate and compare the bursting strength of 100% cotton and cotton-spandex blended knitted fabrics.

To assess key mechanical parameters including bursting pressure, membrane distension, and time to rupture under uniform multi-directional stress.

To implement ISO standard testing procedures for reproducibility and industry alignment.

3. Testing Standard

Standard Applied: ISO 13935-2:1991 (Textiles — Seam tensile properties — Part 2: Determination of maximum force to seam rupture — Grab method).

Although originally developed for seam rupture, the standard is adapted herein to support the assessment of bursting strength for elastic and knitted fabrics.

4. Equipment Details

Instrument Used: James Heal TruBurst (Hydraulic Bursting Strength Tester)

Test Area: Circular clamp with a test diaphragm of 50 cm², compliant with ISO specifications.

Control & Output: Digital control for inflation rate, and real-time recording of burst pressure, distension, and test duration.

Environmental Conditions: Testing performed under standard atmospheric conditions (21 ± 2°C temperature; 65 ± 4% relative humidity).

5. Materials & Sample Preparation

Sample Code	Fabric Composition	Structure	GSM	Finishing Condition
A	100% Cotton	Single Jersey Knit	160	Relaxed & Conditioned
B	95% Cotton + 5% Spandex	Single Jersey Knit	180	Relaxed & Conditioned

Specimen Count: Minimum 5 specimens per fabric type.

Sample Conditioning: All samples were conditioned for 24 hours in a controlled environment prior to testing.

Sampling Direction: Random orientation—balanced between wale and course direction to eliminate directional bias.

6. Testing Methodology

The fabric specimen is placed over the rubber diaphragm and securely clamped.

Hydraulic fluid inflates the diaphragm at a controlled rate, applying uniform multi-directional force on the specimen.

The instrument records three critical performance parameters:

Bursting Pressure (kPa) – Peak pressure before rupture.

Distension (mm) – Vertical displacement of fabric at rupture.

Time to Burst (s) – Time elapsed from test initiation to rupture.

Post-test evaluation includes visual inspection of rupture pattern and statistical analysis of results.

7. Results & Analysis (Hypothetical Example for Illustration)

Sample	Avg. Bursting Pressure (kPa)	Avg. Distension (mm)	Time to Burst (s)
A	410	18.5	6.2
B	360	26.4	7.8

Observations:

Sample A (100% Cotton) exhibited higher bursting pressure due to limited elasticity and stronger inter-loop cohesion.

Sample B (Cotton-Spandex Blend) displayed higher distension due to elastic behavior but lower burst pressure, indicating stretchability with moderate tensile resistance.

8. Discussion

The results indicate a clear trade-off between fabric extensibility and bursting resistance. While spandex-enhanced fabrics provide superior comfort and flexibility, their structural integrity under load is relatively lower. For applications requiring high-pressure resistance, pure cotton may be preferred, while stretch garments prioritize comfort and shape retention.

Furthermore, standardized bursting strength testing enables textile manufacturers to:

Benchmark fabric durability

Identify structural weaknesses in blends

Ensure consistent quality during production and post-treatment processes

9. Conclusion

The bursting strength test, conducted via James Heal TruBurst and in accordance with ISO 13935-2:1991, offers a reliable and reproducible method for evaluating knitted fabric durability. The experiment highlights key mechanical differences between 100% cotton and cotton-spandex blends, aiding in material selection and product design decisions in the textile and apparel industry.

Bursting Strength Testing of Knitted Fabrics Using James Heal TruBurst | ISO 13935-2 Methodology