N.A.M. Amin

Strain response and damage modelling of glass/epoxy pipes under various stress ratios

Abstract This paper presents the stress–strain response and general lifetime damage modelling of glass fibre reinforced epoxy (GRE) composite pipes subjected to multi-ratios stress loadings at room temperature (RT). This particular modelling work was developed to predict the non-linear stress–strain response caused by the fatigue static and cyclic loading in the multiaxial ultimate elastic wall stress (UEWS) tests by considering the effects of matrix cracking within the laminates. Although the UEWS procedure is not a standard protocol used for qualification of GRE pipes, it appears to offer an option to existing procedures delineated in ASTM D2992. The ply properties initially expressed as a function of crack density was computed as a function of increasing stress and strain using shear lag approximation. In general lifetime damage model, the effects of stress developed in each ply from ultimate elastic wall stress (UEWS) test were expressed in a single quadratic term of axial and hoop stress. The term then solved to produce limits with respect to axial and hoop stress, which represented in a graphical form of failure envelope. The predictions from both models are found to be in good agreement with the data from the multiaxial UEWS tests of ±55° filament wound GRE pipes. These models thus enable for the long term performance prediction of the pipes under combined loadings.

General Lifetime Damage Model for Glass Fibre Reinforced Epoxy (GRE) Composite Pipes under Multiaxial Loading

This paper presents the modelling of a general lifetime performance for glass fibre reinforced epoxy (GRE) composite pipes similar to the well-known Tsai-Hill interactive failure criterion. Tsai Hill criterion is based on the Von Misses distortional energy criterion which was modified to satisfy the orthotropic nature of GRE composite pipes. The effects of stress developed in each ply from ultimate elastic wall stress (UEWS) test were expressed in a single quadratic term of axial and hoop stress through laminate theory. The term then solved to produce limits with respect to axial and hoop stress, which represented in a graphical form of failure envelope. The modelled envelop shows a good agreement with experimental data from the multiaxial UEWS test of ±55° GRE composite pipes. This indicates that such model can be used to predict the long-term performance of GRE pipes under combine loadings.

Investigation of Conducting Pins in Sphere Filled with Phase Change Material for Enhancing Heat Transfer in Thermal Energy Storage

The utilisation of phase change material (PCM) for thermal energy storage (TES) can significantly enhance the energy savings achievable with renewable thermal systems. Sphere based packed bed systems have been used as TES for many years. However, due to the thermal resistance within these systems, the heat transfer is limited and not all the PCM can be used effectively. This study focuses on heat transfer enhancement options for single PCM sphere in a TES system. An experimental investigation has been conducted using water as the PCM. The thermal performance of plain plastic sphere containing PCM has been compared to plastic sphere encapsulated with conducting pins. The heat transfer rate of the sphere with conducting pins was more than 34% that of the sphere without pins.

Tensile Strength of Untreated Napier Grass Fibre Reinforced Unsaturated Polyester Composites

This paper describes the experimental investigation of the tensile strength of untreated Napier grass fibre reinforced polyester composites. Napier grass fibres were extracted trough conventional water retting process and used as reinforcing materials in the polyester composite laminates. Tensile tests were then conducted for the composite specimens from the laminates at 25% fibre loading using the electronic extensometer setup to obtain the tensile properties. The results show significant differences in tensile strength between random short fibres laminates and random long fibre laminates with the long fibres yield almost 45 % higher in the strength. The laminates also show higher maximum strength compared to other commonly available natural fibre composites with over 70 % increase in the maximum strength compared to the short kenaf fibre reinforced composites.

Ageing Effects on Burst Pressure Test of Impacted Glass Fibre Reinforcement Epoxy (GRE) Pipes.

The main objective of this experimental study is to investigate the effects of hydrothermal ageing on the pressure bearing capacity of the E-glass/epoxy composite pipes subjected to impact loadings. The pipes were produced by the conventional filament winding technique comprises of six antisymmetric layers with (±55°)3 winding angles. The pipes were immersed in tab water for period of 500, 1000, and 1500 hours. The specimens were impacted at three different energy levels; 5 J, 7.5 J, and 10 J using an instrumented drop weight impact testing machine (IMATEK IM10). The samples were then subjected to pressure test until distinct leakage failure is observed. The results indicates that peak force and contact time increase with increasing impact energy. The tests results show that the burst pressure decreases with increase in energy levels during impact loading. During the burst tests, several damage types named leakage and eruption were observed.

Burst strength of glass fibre/epoxy composite pipes subjected to impact loading

The main objective of this experimental study was to investigate the effects of low velocity impact loading on the pressure bearing capacity of the E-glass/epoxy composite pipes. The pipes were produced by the conventional filament winding technique comprises of six axisymmetric layers with (±55°)3 winding angles. The specimens were impacted at three different energy levels which are 5 J, 7.5 J, and 10 J using an instrumented drop weight impact testing machine (IMATEK IM10). The samples were then filled with water and subjected to burst test until distinct leakage failure is observed. The results indicate that the peak force and contact time increases with increased of impact energy. For impacted samples, the pressure tests show that the burst strength of the pipes decreases with increase in energy levels during impact loading. During the burst tests, several damage types named leakage and eruption were observed.

Experimental Investigation of PCM Spheres in Thermal Energy Storage System

This paper presents the experimental result of a small scale packed bed of random spheres with encapsulated PCM being charged and discharged. A vapor compression refrigerator and heated room with fan heater were used to supply constant heat transfer fluid at a minimum temperature of -28°C for charging and 16°C for discharging. Even though the temperature differences were not fixed in the experiments, the performance of the thermal energy storage is depicted in the form of effectiveness values. Different results were obtained for charging and discharging the thermal storage unit. The differences are expected to come from natural convection and super cooling. The super cooling during the charging process was as high as 6°C.

PLC Trainer Kit Simulator: An Improvement for Automation Study in Polimas

Programmable logic controller (PLC) is a basic and essential element in the engineering of industrial automation. Therefore, basic knowledge of the early stages of PLC plays an important role, especially for mechatronics and manufacturing engineering students. However, due to limited equipment available, high cost equipment, high trainer student ratios, and low reliability of existing equipment, many educational institutions do cannot provide the sufficient resources necessary to help students to become proficient with PLC technology. To alleviate these main problems, the PLC Trainer Kit Simulator is to be developed and used in the Automation Lab at Polytechnic of Sultan Abdul Halim Mu’adzam Shah (POLIMAS). The PLC Trainer Kit Simulator will be used to help student on PLC applications for basic course in JF506 Manufacturing Engineering Laboratory. This study is a descriptive study with a quantitative approach. Evaluation will be determined based on pre-test and post-test. This paper reviews the necessity of the simulation kit prior to its implementation. It is expected that, the teaching and learning processes could become more effective thus contribute to positive impacts on students’ interest in learning PLC.

Stress and Thermal Analysis of CubeSat Structure

This paper presents the stress and thermal analysis on the CubeSat structure to study the survivability of the CubeSat during the launching process or operating condition at the orbit is presented. Various design of mechanical structures were analyzed to determine the best design for different mission requirements. Analysis on the temperature of the batteries will be conducted as it is one of the most critical components that must operate in the required temperature to avoid failure of the CubeSat. ANSYS 13.0 was used to simulate both the structural and thermal analysis. Static structural was used to study the impact of G-force on the CubeSat during the launching process and Icepak was used to study the internal temperature. All of the result will be compiled in the table and comparisons were made among different designs to determine the advantages and disadvantages of each design. Results from simulation such as: safety factor, weight, internal available space and battery discharge rate were analyzed. From the findings, there is no best design in the CubeSat structure but only the most suitable design for the mission purposes. Battery discharge rate will play an important role to determine the requirement of heater in CubeSat.

Effects of Elevated Temperatures on the Compression Strength of Nanoclay Filled Unsaturated Polyester Resin

The paper describes the effects of the montmorillonite (MMT) fillers commonly known as nanoclay, on the compression properties of unsaturated polyester resins at different weight percentage of nanoclay. Modified resin specimens with 1, 3 and 5 wt. % of nanoclay contents were prepared and subjected to compressive tests according to ASTM D695. The static uniaxial compression testing were conducted at various temperatures ranging from room temperature (RT) to the temperature closer to its glass transition temperature Tg to study the effect of nanoclay fillers on the compressive stress-strain behaviour at high temperatures (room temperature, 35, 45, and 75°C). The mechanical properties of the nanomodified resin including the elastic modulus, maximum stress and failure strain were determined. The experimental results imply that adding these nanoclay fillers has enhanced the elastic modulus, compressive strength, and toughness without sacrificing the strain to failure and thermal stability of the unsaturated polyester. However it was found that generally, all specimens showed degradation in compressive strength with increases in temperatures.