Browsing by Author "Janith, GI"

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item: Conference-Full-text
Direct current resistivity based in-situ cure monitoring technique for amine cured epoxy resins
(IEEE, 2022-07) Herath, HS; Janith, GI; Weragoda, VSC; Amarasinghe, DAS; Attygalle, D; Samarasekara, AMPB; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
The Epoxy resins and epoxy resins-based system usage in industrial applications such as composites and electronic materials keep growing. Thus, research focused on enhancing the properties of these resin-based systems is of importance for manufacturing quality controls. Especially monitoring of cure progression and chemo-rheological behavior of epoxy resins are essential for many industries. Commonly practiced cure monitoring methods such as DSC and DMA for the purpose are conducted in laboratories under specified conditions and are not practiced for real-time cure monitoring. However, in-situ cure monitoring techniques are essential for many industries as they provide more insight and thus more control over processing parameters. This study introduces a direct current resistivity-based cure monitoring method as it is simple, cost-effective, reliable, and more importantly, industry-friendly. The fast response of direct current measurements combined with the simplicity of the analysis makes this method suitable for real-time sensing applications. The strong correlation between the degree of cure and the viscosity allows us to take simultaneous measurements of both. The method's feasibility was analyzed using two amine cured epoxy resin systems.
item: Conference-Full-text
Linear and non linear creep modeling of talc filled peek composite
(IEEE, 2021-07) Janith, GI; Amarasinghe, DAS; Attygalle, D; Weragoda, VSC; Samarasekara, AMPB; Adhikariwatte, W; Rathnayake, M; Hemachandra, K
The creep compliance of a viscoelastic material is a crucial material parameter that controls the time dependent creep. Viscoelastic materials and their composites are being widely used in electronic and structural components where strain response of such a material is of great concern. Linear viscoelastic models such as the generalized kelvin Voigt model is widely used to model the linear creep behavior. Poly ether-ether ketone is a semi crystalline polymer and in this study a PEEK composite filled with talcum is being used which also consists of a semi crystalline polymer matrix. Such semi crystalline matrixes are known to bring forth nonlinear viscoelastic properties. In this study we model the linear creep behavior and the stress dependent nonlinearity of the above-mentioned composite.
item: Conference-Abstract
A monitoring method for the degree of curing in epoxy adhesives using direct current resistivity
(Department of Materials Science and Engineering, University of Moratuwa., 2022-11) Janith, GI; Herath, WHS; Weragoda, VSC; Abeygunawardana, AAGA
Adhesive bonding is a widely used technique in material joining. Research focused on enhancing the properties of resin-based adhesive systems is critically important in manufacturing quality control. One specifically important aspect is the monitoring of cure progression of the adhesive. Commonly practiced cure monitoring methods such as Differential Scanning Calorimetry (DSC), Dielectric Analysis (DEA) and Dynamic Mechanical Analysis (DMA) are ideal for laboratory evaluations but not conducive for in-situ cure monitoring. In-situ cure monitoring techniques are vital as they provide better control over processing parameters. This study introduces a Direct Current Resistivity (DCR) based cure monitoring method. It is simple, cost-effective, reliable, and more importantly, industry friendly. The fast response of direct current measurements combined with the simplicity of the analysis makes this method suitable for real-time cure monitoring.
item: Conference-Full-text
A novel method on fitting a short prony series using creep or stress relaxation data
(IEEE, 2022-07) Janith, GI; Herath, HS; Amarasinghe, DAS; Attygalle, D; Weragoda, VSC; Samarasekara, AMPB; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
The time dependent viscoelastic properties such as creep and stress relaxation are very important properties to be considered when designing with viscoelastic materials working at high temperature or extreme conditions. Mechanical models consisting of springs and dashpots are used to model these time dependent properties. Determining these models is done by fitting a Prony series to experimental creep or stress relaxation data. Most of the Finite Element Analysis softwares that are capable of viscoelastic modeling also uses Prony series to characterize such a material. Therefore, it is useful to have a fast, simple, and mathematically less cumbersome method to fit such a Prony series. The novel method introduced in this paper can be used to fit a short Prony series and makes the process much simpler and faster.