The deformation behaviour of different types of closed cell aluminium foam (Alulight, Alporas) was studied.Compression tests indicate that inhomogeneities in the density distribution might be the key factor in determining the mechanical behaviour of foams. Strengthening and softening of the foam can be related to the formation of deformation bands. Depending on the composition and the microstructure of the cell wall material, cells undergo either ductile or brittle collapse. A three dimensional ®nite element analysis, which has the capability to simulate the initial deformation of foam samples, is presented. Continuum mechanics methods are used to describe the behaviour of foam. Each foam sample is divided into subregions, according to their density distribution. Scaling laws are used to simulate the mechanical properties of the subregions. Experimental data are compared with results of the presented model. Very good agreement between experiments and modelling was found for the rather inhomogeneous Alulight material.MST/4547
The uniaxial tensile modulus and strength of Alulight® foams are measured and simulated taking into account the non‐uniform mass density distribution characterized non‐destructively by X‐ray computer tomography. The density mapping method is employed for the reconstruction of the hard and soft regions in the samples investigated. A finite element (FE)‐model is introduced for simulations of the deformation of a continuum composed by domains of different local densities. Existing constitutive laws for cellular structures are incorporated for the numerical simulation of tensile deformation and the variance of the material parameters is determined with the aid of a scaling relationship. The experimental results for the stiffness, the ultimate strength, and the corresponding strain agree with the developed 3D FE simulations and are compared with the estimations according to scaling laws for uniform cellular structures. The non‐uniformity of the material distribution affects the strength and the ductility significantly. Simulations taking this into account provide conservative property predictions. The calculated positions of local strain concentration correspond with the observed locations of crack initiation. The material modelling and the simulation of the elasto‐plastic deformation up to damage are suggested for application to macroscopic components made of non‐uniform cellular metals.
To detect adulteration in gasoline, an automatic distillation apparatus was set up to measure the recovered volume and temperature simultaneously. The level metering was performed by online image processing instead of the conventional visual operator‐based measurement. To investigate the effect of additives in super gasoline, regular gasoline and diesel were added and the distillation curves were analyzed. The principal component analysis model was employed to reduce the obtained data. Finally, an artificial neural network was applied to predict the volume percentage of adulterants in super gasoline. Statistical analysis showed that the proposed model has a mean relative error and correlation coefficient of 4.6 % and 0.995, respectively.
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