Research on ultrasonic-based investigation of mechanical properties of ice

Arctic sea ice area and thickness have declined dramatically during the recent decades.Sea ice physical and mechanical properties become increasingly important.Traditional methods of studying ice mechanical parameters such as ice-coring cannot realize field test and long-term observation.A new principle of measuring mechanical properties of ice using ultrasonic was studied and an ultrasonic system was proposed to achieve automatic observation of ice mechanical parameters(Young’s modulus,shear modulus and bulk modulus).The ultrasonic system can measure the ultrasonic velocity through ice at different temperature,salinity and density of ice.When ambient temperature decreased from 0°C to-30°C,ultrasonic velocity and mechanical properties of ice increased,and vice versa.The shear modulus of the freshwater ice and sea ice varied from 2.098 GPa to 2.48 GPa and 2.927 GPa to 4.374 GPa,respectively.The bulk modulus of freshwater ice remained between 3.074 GPa and4.566 GPa and the sea ice bulk modulus varied from 1.211 GPa to 3.089 GPa.The freshwater ice Young’s modulus kept between 5.156 GPa and 6.264 GPa and sea ice Young’s modulus varied from 3.793 GPa to 7.492 GPa.The results of ultrasonic measurement are consistent with previous studies and there is a consistent trend of mechanical modulus of ice between the process of ice temperature rising and falling.Finally,this ultrasonic method and the ultrasonic system will help to achieve the long-term observation of ice mechanical properties of ice and improve accuracy of sea ice models.