Relationship between the residual and total strain from creep‐recovery tests of polypropylene/multiwall carbon nanotube composites

2020

Electrical conductivity of glass fiber-reinforced plastic with nanomodified matrix for damage diagnostic

2021

The electrical conductivity of glass fiber-reinforced plastic (GFRP) with epoxy matrix modified by multiwall carbon nanotubes (MWCNT) was studied. The electrical conductivity of nanomodified lamina and multi-layered GFRP was investigated on several levels using a structural approach. Components of the electrical conductivity tensor for unidirectional-reinforced monolayer were calculated similarly as in micromechanics using the conductivity of the nanomodified matrix. The electrical conductivity of multilayer composite was calculated using laminate theory and compared with values measured experimentally for various fiber orientation angles. Calculated and experimental data were in good agree…

Development of Removable Visual Impact Indicator or Polymer Composite Materials

2021

The prototype of removable visual impact indicator for thermoset polymer composite materials is developed, and its characteristics are experimentally determined. The indicator is a fabric tape glued by epoxy to the surface of the polymer composite. The tape is impregnated with a composition that provides a visual response at the place of an impact on the composite surface. Ball-drop tests demonstrated the increase of the magnitude of the visual response with the impact energy at different substrate hardnesses. The shelf-life and mode of the tape storage until commissioning are determined. Peel tests showed the ability to remove a used indicator without damaging the surface of the composite.

Development and determination of properties of damage visual indication system for polymer composite structures

2021

Tiek piedāvāts jauns koncepts tehniskā stāvokļa monitoringam (TSM) kompozītmateriāla elementiem. Koncepta realizācijai tika izstrādāta Bojājumu Vizuālās Indikācijas Sistēma (BVIS). Tā sastāv no auduma pamatnes, kas piesūcināta ar krāsvielu un krāsu aktivatoru mikrokapsulās. No pieliktās ārējas slodzes mikrokapsulas saplīst un saturs nonāk kontaktā, ķīmiskās reakcijas rezultātā notiek krāsu izmaiņa un slodzes vieta var tikt vizuāli identificēta. BVIS bija notestēts dažādiem pielietojumiem un tās izturība tika apstiprināta. Piedāvātais koncepts ļaus samazināt kompozītmateriālu tehniskā stāvokļa pārbaudes laiku, vienkāršos virsmu pārbaudi bez aparatūras. Šādi tiks paaugstināta ekspluatēšanas d…