FEM ANALYSIS AND EXPERIMENTAL TESTS ON A DEVICE FOR POURING CONCRETE

Aim of the paper is the prediction of the on-service behaviour of an articulated device for pouring concrete composed of five arms. Experimental tests have been performed on a prototype of the equipment made on Weldox 900E steel, while a parallel finite element analysis has been made on a virtual model of the device. Comparison of experimental tests and numerical analysis allows to gain a deep insight on the performance of the apparatus. A virtual model of the apparatus has been developed by a 3D CAD modeller and analyzed through FEM numerical programs in both static and dynamic conditions. During dynamic simulation, accurate evaluation of all loadings and constraints have been made and a modal analysis has been performed on the whole structure to identify critical frequencies. Test plans have been devised to assess performance of the articulated device in both static and dynamic conditions by instrumenting the prototype of the equipment with rectangular rosettes. During quasi-static tests, a series of known discrete loads (up to roughly 1800 N), measured by a dynamometer, has been applied at the end of the fifth arm of the structure. Deflections at the end of the fifth arm, corresponding to each applied load, have been measured by a laser device, utilizing, as reference, the configuration at rest of the structure. Strains are measured by the strain gages of each rosette. Dynamical tests have been performed, by simulating experimentally concrete pouring. During both static and dynamic tests, the 3D strain state and the 2D plane stress state can be derived in each site where rectangular rosettes have been located. Principal stresses, principal strains, direction of the principle strains and stresses, Mohr stress and strain circles have been recorded and compared with those predicted through the finite element analysis. Comparison between numerical and experimental results has been carried out. A very good correlation has been obtained for static loading to assess the soundness of the virtual model. Both experimental tests and numerical simulation in the on-service condition allow to identify the more dangerous resonance frequencies