Failure testing of gellan gels

Abstract

Gels, formed using a 1% gellan gum solution containing 7 m m calcium ions, were tested to failure in compressive, tensile and torsional modes. The gels were brittle and fractured at relatively small strains. In the compression experiments samples failed in shear at low deformation rates, and in a combination of compression and shear at higher strain rates. Tensile fracture was always evident in uniaxial tension measurements, and in the torsion experiments at low strain rates. At high deformation rates the torsional samples underwent a combination of shear and tensile fracture. The three tests were compared on the basis of the shear stress and strain at failure. The shear stress agreed in all cases. The strain only agreed in the compressive and torsional modes and was an order of magnitude lower in tension.