Applied Solid and Fracture Mechanics

The Southwest Research Institute® (SwRI®) Solid and Fracture Mechanics Laboratory (Solids Lab) provides test data for understanding the structural integrity of a specimen, coupon, subcomponent, or structural test element. Uniaxial servohydraulic test frames are used for applying tension, compression, bending, or mixed loading modes on test samples. The laboratory also contains the instrumentation and data acquisition hardware required to measure and record load, displacement, strain, and other transducer data. Applications range from the simplest tensile test to variable-amplitude, spectrum crack growth (SCG) testing.

Heat tinting clearly illustrates different crack propagation regions in fracture tests.


With more than 40 years of experience, the SwRI Solids Lab provides test data on: 

  • Tensile and compressive properties

  • Fatigue, fatigue crack growth and fracture toughness

  • Specialized fracture mechanics

  • High-rate constitutive properties

  • Corrosion fatigue and high-temperature fatigue (including LCF and TMF)

High-temperature fatigue properties are measured on a single crystal nickel alloy.

Low-temperature (note white frost) toughness is evaluated on a pressurized steel airbag inflation cylinder subjected to four-point loading.

Quasi-static or cyclic test setups and evaluations can be conducted in the Solids Lab with a unique setup of complex and specialized fixtures. Extensive capabilities also exist for performing variable-amplitude, SCG tests in which the loads recorded during service (or theoretical design loads) are applied to the test coupon.

Data generated in SwRI's Solids Lab have been used by virtually all industries including aerospace, oil and gas, and transportation, as well as numerous 
government entities.

The state-of-the-art Solids Lab is housed in a high bay that can accommodate oversize test components.


The 6,500-square-foot Solids Lab contains uniaxial test frames with closed-loop computer control capability. A partial list of equipment includes:

  • More than 20 servohydraulic and three servoelectric test frames ranging from 
    1 to 200 kips

  • Eleven fully automated fatigue crack growth test control systems (FTA) allowing K-control (for da/dN testing) and variable-amplitude SCG tests

  • Seven LabVIEW 16-bit data acquisition systems and high-speed, transient 
    12-bit DSOs

  • Direct and indirect potential drop for nonvisual crack measurement

  • Extensometers, microprofilers, and strain amplifiers

  • Resistance and quartz lamp ovens (2000F maximum)

  • Induction furnaces (temperature grip limited) and molydisilicide element 
    furnace (3600F)

  • Enclosures for aggressive and high-temperature environments

  • High-cycle fatigue frame (>1000 Hz)

  • Two split Hopkinson pressure bars (120 and 340 ksi maximum stress)

An extensive supply of grips and fixtures is available to test realistic fatigue-critical locations.

A miniature disk-shaped carbon specimen is rigged with an acoustic emission sensor.

This flyer was published in April 2001. For more information about applied solid and fracture mechanics, contact Dr. Carl F. Popelar, Manager, Mechanics and Materials Section, Solid and Fracture Mechanics Laboratory, Mechanical Engineering Division, Southwest Research Institute, P.O. Drawer 28510, San Antonio, Texas 78228-0510, Phone (210) 522-3617, Fax (210) 522-6965.

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