Fracture Toughness & Fatigue Testing

The Fracture Toughness Test determines how well a material can resist the growth of a crack under an increasing load. The fracture toughness values identified by the test are useful in material selection and in determining whether there is a danger of component failure when a flaw is discovered in an existing structure.

The salient features are:

  • Capability to test various specimen geometries like compact tension (CT), bend specimen (SEB), disk shaped (DCT), arc shaped tension (AT) and arc shaped bend (AB).
  • Capability to handle specimens of many sizes.
  • Onsite machining and Specimen preparation.
  • Customized test setups and fixtures.
  • Computer data acquisition for accurate and timely results.
  • Customized servo hydraulic equipment to perform the test.
KIc Testing
Linear-Elastic Plane-Strain Fracture Toughness

Fracture toughness testing according to ASTM E399 applies a continuously increasing load to the specimen and determines the critical stress intensity KIc. This method is known as the KIc test, KIC or K1C fracture toughness test. It is a widely used test, particularly in aerospace industry standards.

Test Methods:

  • ASTM E399, B645, B646, B909
  • ISO 12135
  • BS 7448-1
  • ASTM E2818 (For welds)
  • ISO 15653 (For welds)
  • BS 7448-2 (For welds)
JIc Testing
Elastic-Plastic Fracture Toughness

During testing to ASTM E1820, a rising load with periodic partial unloading is applied to measure the crack length as the test progresses. Since this method takes measurements throughout the test, it provides a lot of data on the behavior of the material as the crack opens, so it is often possible to get valid results where it would be impossible or unfeasible with a KIc test.

Test Methods:

  • ASTM E1820
  • ISO 12135
  • BS 7448-1
  • ASTM E2818 (For welds)
  • ISO 15653 (For welds)
  • BS 7448-2 (For welds)
CTOD Testing
Crack Tip Opening Displacement test

The Crack Tip Opening Displacement or CTOD Test measures the resistance of a material to the propagation of a crack. CTOD is used on materials that can show some plastic deformation before failure occurs causing the tip to stretch open. Accurate measurement of this displacement is one of the essentials of the test.

Test Methods:

  • ASTM E1820
  • ISO 12135
  • BS 7448-1
  • ASTM E2818 (For welds)
  • ISO 15653 (For welds)
  • BS 7448-2 (For welds)
Fatigue Crack Growth Rate

Fatigue Crack Growth Rate (da/dN) Testing is designed to determine the rate of cracking under specified loading conditions once a flaw has been initiated in the specimen. The graph of Cyclic Stress is plotted against the Crack Growth Rate, with stress intensity being the controlling variable.

Fatigue Crack Growth Rate Results are reported in both tabular and graphical formats. Paris Law and threshold values are provided. The graphs include both da/dN vs. ΔK and Crack Length vs. Cycles.

Test Methods:

  • ASTM E647
  • ISO 12108
Low Cycle Fatigue Testing

Low cycle fatigue (LCF) is low-cycle endurance testing, where components are subject to mechanical cyclic plastic strains that cause fatigue failure within a short number of cycles.

The low-cycle fatigue test is generally run slowly with a relatively short number of cycles to failure. This test is characterized by high amplitude, low-frequency plastic strains.

Test Methods:

  • ASTM E606
  • ASTM E466
  • ISO 12110
Reinforcement Coupler Testing

We can do the testing what are all in the standard IS 16172 - For reinforcement couplers for mechanical splices in concrete. The tests are,

  • 1.Static tensile test
  • 2. Slip test
  • 3. Cyclic tensile test
  • 4. Fatigue test
  • 5. High cycle fatigue test
  • 6. And other tests given in ASME secII

Test Methods:

  • IS 16172
  • ISO 15835