Design of an Experimental Set‑up Concerning Interfacial Stress to Promote Measurement Accuracy of Adhesive Shear Strength Between Ice and Substrate

Accumulation of ice on airfoils and engines seriously endangers the safety of the fight.The accurate measurement of adhesion strength at the ice-substrate interface plays a vital role in the design of anti/de-icing systems.In this pursuit,the present study envisages the evaluation of the stress at the icesubstrate interface to guide the design of experimental set-ups and improve the measurement accuracy of shear strength using the finite element analysis(FEA)method.By considering such factors as the peeling stress,maximum von-mises stress and uniformity of stress,the height and radius of ice and the loading height are investigated.Based on the simulation results,appropriate parameters are selected for the experimental validation.Simulation results show that the peeling stress is decreased by reducing the loading height and increasing the height of ice.Higher ice,increasing loading height and smaller ice radius are found to be beneficial for the uniformity of stress.To avoid cracks or ice-breaking,it is imperative that the ice should be of a small radius and greater height.Parameters including the ice height of 25 mm,radius of 20 mm,and loading height of 9 mm are adopted in the experiment.The results of FEA and the experimental validation can significantly enhance the measurement accuracy of shear strength.

Stability analysis of shallow tunnels subjected to eccentric loads by a boundary element method

This paper presents the results of the shear strength（frictional strength） of cemented paste backfillcemented paste backfill（CPB-CPB） and cemented paste backfillerock wall（CPB-rock） interfaces. The frictional behaviors of these interfaces were assessed for the short-term curing times（3 d and 7 d） using a direct shear apparatus RDS-200 from GCTS（Geotechnical Consulting ＆ Testing Systems）. The shear（friction） tests were performed at three different constant normal stress levels on flat and smooth interfaces. These tests aimed at understanding the mobilized shear strength at the CPB-rock and CPB-CPB interfaces during and/or after open stope filling（no exposed face）. The applied normal stress levels were varied in a range corresponding to the usually measured in-situ horizontal pressures（longitudinal or transverse） developed within paste-filled stopes（uniaxial compressive strength, s c 150 k Pa）. Results show that the mobilized shear strength is higher at the CPB-CPB interface than that at the CPB-rock interface. Also, the perfect elastoplastic behaviors observed for the CPB-rock interfaces were not observed for the CPB-CPB interfaces with low cement content which exhibits a strain-hardening behavior. These results are useful to estimate or validate numerical model for pressures determination in cemented backfill stope at short term. The tests were performed on real backfill and granite. The results may help understanding the mechanical behavior of the cemented paste backfill in general and, in particular, analyzing the shear strength at backfillebackfill and backfill-rock interfaces.