|1.||Taczała M., Buczkowski R., Kleiber M., Nonlinear buckling and post-buckling response of stiffened FGM plates in thermal environments, COMPOSITES PART B-ENGINEERING, ISSN: 1359-8368, DOI: 10.1016/j.compositesb.2016.09.023, Vol.109, pp.238-247, 2017|
Taczała M., Buczkowski R., Kleiber M.
, Nonlinear buckling and post-buckling response of stiffened FGM plates in thermal environments
, COMPOSITES PART B-ENGINEERING
, ISSN: 1359-8368
, DOI: 10.1016/j.compositesb.2016.09.023
, Vol.109, pp.238-247, 2017
We present a nonlinear finite element method to investigate the nonlinear stability of stiffened functionally graded materials (FGM) plates considered as a whole unit. The plates are subjected to mechanical and thermal loads. The material properties are assumed to be temperature dependent and varied gradually across the thickness according to a power law distribution. The nonlinear equations of FGM plates are based on the first-order shear order plate theory. The influence of material, geometrical properties of stiffeners and initial deflections on the buckling and post-buckling response of the stiffened plates are studied in detail. Including the latest information no work has been oriented towards post-buckling analysis of stiffened FGM plates considered as a whole unit.
FGM stiffened plate, nonlinear finite element analysis, post-buckling
|2.||Labra C., Rojek J., Oñate E., Discrete/Finite Element Modelling of Rock Cutting with a TBM Disc Cutter, Rock Mechanics and Rock Engineering, ISSN: 0723-2632, DOI: 10.1007/s00603-016-1133-7, Vol.50, pp.621-635, 2017|
Labra C., Rojek J.
, Oñate E., Discrete/Finite Element Modelling of Rock Cutting with a TBM Disc Cutter
, Rock Mechanics and Rock Engineering
, ISSN: 0723-2632
, DOI: 10.1007/s00603-016-1133-7
, Vol.50, pp.621-635, 2017
This paper presents advanced computer simulation of rock cutting process typical for excavation works in civil engineering. Theoretical formulation of the hybrid discrete/finite element model has been presented. The discrete and finite element methods have been used in different subdomains of a rock sample according to expected material behaviour, the part which is fractured and damaged during cutting is discretized with the discrete elements while the other part is treated as a continuous body and it is modelled using the finite element method. In this way, an optimum model is created, enabling a proper representation of the physical phenomena during cutting and efficient numerical computation. The model has been applied to simulation of the laboratory test of rock cutting with a single TBM (tunnel boring machine) disc cutter. The micromechanical parameters have been determined using the dimensionless relationships between micro- and macroscopic parameters. A number of numerical simulations of the LCM test in the unrelieved and relieved cutting modes have been performed. Numerical results have been compared with available data from in-situ measurements in a real TBM as well as with the theoretical predictions showing quite a good agreement. The numerical model has provided a new insight into the cutting mechanism enabling us to investigate the stress and pressure distribution at the tool–rock interaction. Sensitivity analysis of rock cutting performed for different parameters including disc geometry, cutting velocity, disc penetration and spacing has shown that the presented numerical model is a suitable tool for the design and optimization of rock cutting process.
Rock cutting, Disc cutters, TBM, Numerical model, Discrete/finite element method, Simulation
|3.||Nosewicz S., Rojek J., Chmielewski M., Pietrzak K., Lumelskyj D., Application of the Hertz formulation in the discrete element model of pressure-assisted sintering, GRANULAR MATTER, ISSN: 1434-5021, DOI: 10.1007/s10035-016-0699-9, Vol.19, No.1, pp.16-1-8, 2017|Nosewicz S.
, Rojek J.
, Chmielewski M., Pietrzak K.
, Lumelskyj D.
, Application of the Hertz formulation in the discrete element model of pressure-assisted sintering
, GRANULAR MATTER
, ISSN: 1434-5021
, DOI: 10.1007/s10035-016-0699-9
, Vol.19, No.1, pp.16-1-8, 2017
This paper presents the numerical modelling of initial powder compaction and pressure-assisted sintering performed by original viscoelastic discrete element model. The research is focused on the influence of the type of the model representing an elastic part of interparticle force. Two elastic contact models—linear and nonlinear Hertz model—have been implemented and used to analyse interaction of NiAl powder particles during compaction and sintering process. Numerical models have been validated using own experimental results. Microscopic effects (particle penetration) and macroscopic changes (relative density) have been compared. It has been shown that although both models represent properly macroscopic behaviour of the material at the sintering process, the Hertz model produces the results closer to the real experimental ones during the initial compaction stage. Evaluation of macroscopic quantities enables implementation of the discrete element model in the framework of the multiscale modelling framework which is currently developed for sintering processes.
Powder metallurgy, Sintering, Initial compaction, Elasticity, Discrete element method