This paper concerns the analysis of five-layer corrugated paperboard subjected to a four-point bending test. The segment of paperboard was tested to determine the bending stiffness. The investigations were conducted experimentally and numerically. The non-damaging tests of bending were carried out in an elastic range of samples. The detailed layers of paperboard were modelled as an orthotropic material. The simulation of flexure was based on a finite element method using Ansys® software. Several material properties and thicknesses of papers in the samples were taken into account to analyse the influence on general stiffness. Two different discrete models based on two geometries of paperboard were considered in this study to validate the experimental stiffness. The present analysis shows the possibility of numerical modelling to achieve a good correlation with experimental results. Moreover, the results of numerical estimations indicate that modelling of the perfect structure gives a lower bending stiffness and some corrections of geometry should be implemented. The discrepancy in stiffness between both methods ranged from 3.04 to 32.88% depending on the analysed variant.

Ëîäçèíñêèé òåõíè÷åñêèé óíèâåðñèòåò, Ëîäçü, ÏîëüøàÏðåäñòàâëåíî ÿâëåíèå ïîòåðè óñòîé÷èâîñòè ïðè ñòàòè÷åñêîé è äèíàìè÷åñêîé íàãðóçêå (èìïóëüñ êîíå÷íîé äëèòåëüíîñòè) ôóíêöèîíàëüíî-ãðàäèåíòíûõ ïëàñòèí, ïîäâåðaeåííûõ âîçäåéñòâèþ ðàâíîìåðíîãî ïîâûøåíèÿ òåìïåðàòóðû. Ðàññìîòðåíû øàðíèðíî îïåðòûå èëè çàêðåïëåííûå (âäîëü êðîìîê) òîíêèå ïðÿìîóãîëüíûå ïëàñòèíû ñ íåïîäâèaeíûìè êðîìêàìè. Ïðåäïîëàãàåòñÿ, ÷òî ñâîéñòâà ìàòåðèàëà, ïëàâíî èçìåíÿþùèåñÿ ïî òîëùèíå, íå çàâèñÿò îò òåìïåðàòóðû. Ïðîâåäåíû èññëåäîâàíèÿ äëÿ ðàçíûõ çíà÷åíèé êîýôôèöèåíòà îòíîñèòåëüíîãî îáúåìà è ðàâíîìåðíîãî ïðèðàùåíèÿ òåìïåðàòóðû, ïðåäñòàâëåííîãî â âèäå ïðÿìîóãîëüíîãî èìïóëüñà êîíå÷íîé äëèòåëüíîñòè.Êëþ÷åâûå ñëîâà: äèíàìè÷åñêîå âûïó÷èâàíèå, ôóíêöèîíàëüíî-ãðàäèåíòíûå ïëàñòèíû, òåïëîâàÿ íàãðóçêà.Introduction. Known since 1984 functionally graded materials (FGM) very soon became popular in scientific research and engineering applications. Typical FGM is an inhomogeneous composite made up of two constituents -typically of metallic and ceramic phases which relative content changes gradually across the thickness of a plate or a shell. This eliminates the adverse effects between the layers (e.g., shear stress concentrations and/or thermal stress concentrations), typical for layered composites. The high-resistance heat capacity of ceramic and good mechanical properties of metal phase make that the leading application area of FGM structures are high-temperature environments (spacecraft, nuclear reactors or structures for the chemical industry and defence) [1,2].Nonlinear analysis of plates and shells devoted to basic types of loads is covered in Shen monograph [2]. He considered static bending and thermal bending as an introduction to buckling and postbuckling behaviour of FGM plates and shells. The shear deformation effect is employed in the framework of Reddy's higher order shear deformation theory (HSDT).

This work concerns the analysis of a thin-walled box made of ceramic and step-variable functionally graded material (FGM) subjected to compression. The components of the box taken into account were pure alumina and aluminium-alumina graded material. The problem was solved on the basis of a finite element method and Koiter’s asymptotic theory using a semi-analytical method (SAM). It analysed both the buckling state and the post-buckling state of the box. In addition, three conditions were considered: The presence of alumina outside or inside of the box and a mixed case. The obtained results were presented and discussed.

No abstract

The present paper analyses the properties of printed polylactic acid (PLA) samples with admixtures of graphene nanopowder (GNP) at wt. 1%, 2% and 4%. The pure polylactide and admixed polylactide printed samples were examined to determine their chemical-physical properties, stiffness, and strength parameters. The tests of tensile, dynamic mechanical analysis (DMA), difference thermogravimetric (TG), and differential scanning calorimetry (DSC) were executed before and after UV (ultraviolet) treatment. The first part of the paper shows the process of manufacturing granulates and filaments mixed with graphene. The second part of the paper concerns the results of the tests made on printed samples. The analysed samples were printed using a Prusa i3 MK3 printer. It transpired that the content of graphene at 1% improved the mechanical parameters of the printed composite by organising its structure. Increasing the amount of graphene caused the values of the measured parameters to drop. This research indicates how important it is to determine the optimal values of nanoadditives in biopolymers.