Browsing by Author "Nadarajah, S"

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item: Conference-Full-text
3d full-field deformation measuring technique using digital image correlation
(IEEE, 2020-07) Nadarajah, S; Arulkumar, V; Mallikarachchi, C; Weeraddana, C; Edussooriya, CUS; Abeysooriya, RP
Full-field deformation measurements are crucial as it offers detailed information to better understand both micro and macroscopic nature of material behavior. The practice of employing Digital Image Correlation (DIC) based measuring techniques in experiments has increased due to its ability to generate full-field deformation information with minimal effort. Even though DIC systems are commercially available, the affordability of those systems is questionable in local context due to high capital costs. Most of the past studies related to DIC were focused on testing concrete, masonry and metallic alloy specimens, and little effort has been made on materials with recoverable large elongations. This paper presents a 3D fullfield deformation measuring system that has been developed with a special focus on hyperelastic materials. The proposed system requires two common digital cameras for image acquisition, as the depth information is of interest. Images are then processed using the MATLAB-based algorithm developed to produce the full-field deformation map. Hyperelastic specimens of two different thicknesses were tested over 70% strain and the accuracy of the strain measurement using the proposed system is validated against physical measurements. The results have shown that the strains can be captured to an accuracy greater than 90% using the proposed technique.
item: Conference-Full-text
Fire under control: enhancing warehouse safety through strategic fire prevention and risk management
(Department of Building Economics, 2024) Nadarajah, S; Kulatunga, U; Weerasooriya, D; Rathnasinghe, AP; Sandanayake, YG; Waidyasekara, KGAS; Ranadewa, KATO; Chandanie, H
Warehouse fires represent a global challenge, inflicting economic losses, damaging reputational integrity, disrupting business operations, leading to job losses, and negatively impacting the environment. Despite strict fire regulations and codes of practice aimed at safeguarding warehouse facilities, the prevalence of catastrophic fires persists globally, including notable incidents in Sri Lanka. This persistence prompts an inquiry into the adequacy and appropriateness of current protective measures. This research addresses the urgent need to discern the root causes of warehouse fires and the consequent damages to devise effective preventative strategies. Through a combination of literature review and semi-structured interviews with ten experts, this study employs manual content analysis to explore underlying factors. Key findings indicate that failures often stem from the absence, inadequacy, or improper maintenance of fire detection and protection systems, the specific nature of storage configurations, the size of the facilities, and the combustible characteristics and volume of stored goods. The study proposes adhering to the Construction Industry Development Authority (CIDA) fire regulations, which mandate the provision and maintenance of active and passive fire protection measures. It further recommends the regular execution of fire risk assessments, the enforcement of stringent housekeeping protocols, the strategic separation of commodities based on their class and compatibility, and the isolation of battery re-charging operations from storage areas as critical steps to mitigate fire risks in warehouses. These insights guide warehouse owners, tenants, fire risk assessors, and other professionals who enhance fire safety in warehouse settings.
item: Conference-Abstract
Nonlinear bending response of two-ply plain woven carbon fibre composites
Nadarajah, S; Jayasekara, M; Mallikarachchi, C
Ultra-thin woven fibre composites are becoming popular in weight sensitive applications and hence it is important to predict their mechanical properties for design improvements. This paper presents a simple homogenized micro-mechanical modelling technique with solid elements for predicting mechanical properties of the thin woven fibre composites. A representative unit cell has been generated using a finite element pre-processor, TexGen and an elliptical crosssectioned yarn is then idealized to behave according to Kirchhoff – Love plate theory. Bezier spline is chosen as a suitable interpolation function for the composite, and further analysis is performed with two distinct unit cell representations. It is shown that a simple 3D solid model with idealized elliptical cross section predicts both in-plane and bending properties with good accuracy in the linear regime. The proposed 3D models are capable of predicting the response in the nonlinear regime and has overcome the anomalies faced with 1D model with respect to shear and Poisson’s ratio.