Glass-reinforced Polyester Research Articles

THE USE OF GLASS-REINFORCED POLYESTER IN PRESTON BUS STATION

This article describes the use of glass-reinforced polyester (GRP) in Preston Bus Station in Lancashire, England, designed by Building Design Partnership (BDP) and completed in 1969. GRP was used both for concrete moulds that play a key role in enabling the construction of the building’s distinctive elevation, and for kiosks, signage and smaller fittings. A survey of articles shows that the use of GRP for concrete moulds enabled innovative and efficient construction and this practice continues to date. Some smaller fittings in GRP which were expected to be durable and maintenance-free have been modified, damaged, or removed, yet, others survive and are in a good condition. The legacy of the car park pay kiosks was to last as a prototype for a prefabricated sectional building system.

THE ‘SHELTER’ ALMOST SAVED BY HENDRICK DE KEYSER

The ‘Shelter’ is a fantastic example of a circular plastic house with a diameter of 8 m that is somehow comparable to the ‘Futuro’. It was conceived by the Dutch interior architect Kor Aldershoff, who developed a prototype in glass-reinforced polyester (GRP) shells held on a metal frame (1971). This kind of house is unique for the Netherlands and therefore of great importance. The ‘Shelter’ was meant for providing a home for refugees in Africa. The prototype was light and could also float on water. The production of the metal supporting frame was entrusted to the Nederlandse Dok en Scheepsbouw Maatschappij (N.D.S.M.) in Amsterdam-Noord and the GRP parts to the firm Resicon in Medemblik. The hall, living room and one bedroom were arranged around an empty column for the disposal of rainwater.

EXPERIMENTAL STUDY OF THE STRENGTH OF COMPOSITE MATERIAL MADE OF CARBON FIBRES WITH A MIXTURE OF KEVLAR FIBRES AND PINEAPPLE FIBRES AS AN ADVANCE MATERIAL FOR MINE HUNTER HULL MATERIAL

The advantages of sandwich material compared to metal materials are its lighter weight and low magnetism, making it suitable for use as minehunting ship hull material. In this study, the authors will make a carbon fiber sandwich with a mixture of Kevlar fiber and pineapple sisal fiber compared to GRP (Glass Reinforced Polyester). This research uses the technique of making Vacuum Assessment Resin Infusion (VARI). Strength test with tensile test, impact test and hardness test using ASTM standard. Based on the test results, carbon composite with a mixture of pineapple fiber has a maximum stress of 70,8008 N/mm2 which can be used as a hull material with a maximum length of 24m. While the carbon sandwich with kevlar has a maximum stress of 382,408N/mm2, GRP has a maximum stress of 127.24N/mm2. Carbon fiber material with kevlar can be used for boats longer than 24m.

Effect of the geometry on the structural performance of high-density polyethylene small craft joints

ABSTRACT In today’s marine industry, high-density polyethylene (HDPE) material has gained popularity due to its recyclability that relieves the concerns for sustainability of the products and its lightweight, resistance to environmental effects, such as moisture, corrosion, organisms, UV, etc. its sufficient mechanical properties. HDPE material may be combined with other light materials for structural optimisation. In this work, the performances of three joints – one T-joint and two L-joints – designed by the authors and representing the assembly of HDPE hull and Glass Reinforced Polyester (GRP) composite sandwich superstructure were studied experimentally and numerically. Adhesively bonded, bolted and welded joints were subjected to tensile load. Due to the maximum strain and the failure loads, Type A shows promising performance followed by Type C and B. Type C is more cost-effective while providing a moderate strength followed by Type B and A. Results also affirm the utility of the 2D-FE models for the strain distribution in such joints.

Mechanical Characterization and Optimum Design of Wound Glass-Fiber-Reinforced Polymer Pipes Based on the Winding Angle and the Number of Plies

The design of composite structures is always a very delicate task to ensure that an antisymmetrically wound laminate had the performance required. Our study was carried out with the aim to optimize the performance/cost ratio of these materials. It consisted in the design and manufacture of orthotropic filament-wound glassreinforced polyester (GRP) pipes with different fiber orientation (± 45, ± 55, and ± 70°). Experiments on a 500-mm-diameter GRP pipes wound at different angles were carried out in various mechanical loadings, and the data found were compared with results obtained by analytical methods.

Numerical Investigation on Vibrational Characteristics of Glass Reinforced Polyester Composite Plate

Numerical Investigation on Vibrational Characteristics of Glass Reinforced Polyester Composite Plate

Experimental Measurement of the Resistant Load in Injection Pultrusion Processes

Injection pultrusion (IP) process is a manufacturing technique for producing advanced fiber reinforced polymers having constant cross-section. Unlike the traditional pultrusion process, in which fibers are impregnated passing through an open bath of liquid resin, in IP the uncured polymer is directly injected within the advancing reinforcement in a close chamber generally connected to the die. This paper investigates the resistant forces evolution in IP process at different pulling speeds. Resistant loads are mainly due to the interaction between the advancing material and the die cavity walls, inducing residual stress and, eventually, internal defects. These loads are typically classified in three main contributes, namely fiber collimation, viscous drag and solid friction. The latter two are directly related to the resin degree of cure, and, therefore, the overall resistant load is dramatically sensitive to the changes in operative parameters. In this paper, the resistant force acting along the die cavity has been measured using a dedicated experimental setup. Measurements were performed during the pultrusion of glass-reinforced polyester with different pulling speeds to evidence the variations in resistant load as a function of the process velocity.

Dimensional stability of reinforced bitumen sheets as a possible source of flat roof defects

This paper follows up on the results of a research presented at the conference Building Defects 2017. The paper deals with the dimensional stability of bitumen sheets. The manifestation of insufficient dimensional stability is the shrinkage of bitumen sheets in the transverse joints. Shrinkage of bitumen sheets with reinforced polyester liner and a non-reinforced glass fiber is primarily due to insufficient technological discipline. The paper deals with the influence of melting of the sheet on its possible shrinkage during roof exposure. Previous research has shown that the shrinkage happening during melting accounts for more than 50 % of the total shrinkage. The aim of this paper is to show the size of the effect on the biasing of the load-bearing insert during the realization of the waterproofing layer in bitumen sheets with a glass-reinforced polyester carrier liner. The experiment, expressed by the dimensional stability test according to ČSN EN 1107, was performed in a laboratory on three samples of bitumen sheets. Bitumen sheets had different types of reinforcement and a different weight of the carrier liner.

End-of-Life Alternatives of Glass Reinforced Polyester Boat Hulls Compared by LCA

Glass reinforced polyester (GRP), as a thermoset polymer composites, dominates boat building industry with its several advantages such as high strength/weight ratio, cohesiveness, good resistance to environment. However, proper recovering and recycling of GRP boats is became a current environmental requirement that should be met by the related industry. In this study, to propose in a cost effective and environmentally friendly way, Life Cycle Assessment (LCA) has been carried out for six scenarios include two moulding methods (namely Hand Lay-up Method, HLM and Vacuum Infusion Method, VIM) and three End-of-Life (EoL) alternatives(namely Extruding, Incineration and Landfill) for a recreational boat's GRP hulls. A case study from raw materials purchasing phase to disposal/recycling stages has been established taking 11 m length GRP boat hull as the functional unit. Analysis show that in the production phase, the impacts are mainly due to the use of energy (electricity), transport and raw material manufacture. Largest differences between the methods considered (HLM and VIM) can be observed in the factors of marine aquatic ecotoxicity and eutrophication while the closest ones are abiotic depletion, ozon layer depletion and photochemical oxidation. The environmental impact of VIM is much higher than HLM due to its higher energy consumption while vacuum infusion method has lower risk than hand lay-up method in terms of occupational health by using less raw material (resin) in a closed mold. In the comparison of the three EoL techniques, the mechanical way of recycling (granule extruding) shows better environmental impacts except terrestrial ecotoxicity, photochemical oxidation and acidification. Among the EoL alternatives, landfill has the highest environmental impacts except ‘global warming potential’ and ‘human toxicity’ which are the highest in extrusion. The main cause of the impacts of landfill is the transportation needs between the EoL boats and the licenced landfill site. Although it has the higher impact on human toxicity, incineration is the second cleaner alternative of EoL techniques considered in this study. In fact that the similar trend has been observed both in production and EoL phases of the boat. It is obvious that using much more renewable energy mix and greener transportation alternative can reduce the overall impact of the all phases considerably.

Failure analysis of glass-reinforced polyester mortar pipes with different cores subjected to combined loading

In this paper, the failure of glass-reinforced polyester mortar pipes with different cores subjected to pure and combined loading are analyzed. To enhance the stiffness of fiber-reinforced polyester pipe, filler layer is incorporated in between fiber-reinforced polyester plies. Thus, in this study, new nanocomposite materials are proposed as a core layer in the glass-reinforced polyester mortar pipes. The performance of the pipes in the presence of nanosilica/resin, nanosilica/fiberglass/resin and multi-walled carbon nanotubes (MWCNTs)/resin and sand/resin cores are investigated. Finite element method is used to analyze the effects of extensive design parameters on the first ply failure and functional failure of glass-reinforced polyester mortar pipes. Maximum normal stress, Tsai–Wu and Tsai–Hill criteria are employed for the failure analysis. Two end boundary conditions are considered in the simulations. The effects of core material constituents, core thickness, filament winding angle and lay-up configurations, layers thicknesses and pipe radius are investigated. The results are also obtained under pure and combined loading conditions. The stress concentration around circular and rectangular holes in glass-reinforced polyester mortar pipes with sand/resin core is also studied. Accordingly, the stress concentration factors are reported for each case. Detailed discussions are done and brief design guidelines are given.

Mixed-mode damage into a CGRP cruciform subjected to biaxial loading

In this paper, a three-dimensional progressive damage model (PDM) is implemented within a chopped glass-reinforced polyester (CGRP) cruciform structure for modelling its damage under loading. Three different cruciform specimens subjected to biaxial tensile loading are studied. In order to simulate the computational behaviour of the composite, the constitutive model considers an initial elastic behaviour followed by strain-softening. The initiation criterion defined is based on the maximum principal stress of the composite and once this criterion is satisfied, stiffness degradation starts. For the computation of damage, the influence of the fibre and the matrix are taken into account within the damage rule. Realistic values of the energy dissipated during damage are computed. The computational results obtained by means of an explicit time marching solver are compared with experimental outcomes for validation purposes. Finally, it is concluded that the PDM is able to localise the damage effectively as well as predicting its initiation. In the best of authors’ knowledge, this is the first time a three-dimensional PDM is implemented into a composite cruciform structure subjected to biaxial loading.

In-plane shear failure properties of a chopped glass-reinforced polyester by means of traction–compression biaxial testing

We perform traction–compression biaxial testing in a chopped glass-reinforced polyester, applying in-plane perpendicular tensile–compressive loads to cruciform specimens. The purpose is to evaluate if this technique is suitable to perform shear tests and determine the shear strength and the shear failure strain of the composite. The failure properties obtained experimentally from this technique are compared with the analytical predictions of the Maximum stress, Maximum strain, Tsai-Hill and Tsai-Wu failure theories and the numerical results obtained by means of the Finite Element Method. The analysis is developed taking into account the different behaviour of the material under tension and under compression.

Destructive and nondestructive evaluations of the effect of moisture absorption on the mechanical properties of polyester-based composites

In this study the effect of moisture absorption on the mechanical properties of glass-reinforced polyester composites is evaluated using both destructive and nondestructive tests. The composite resins were produced with two different production processes, while the mechanical properties of the composite materials were measured using DMA destruction tests. According to the DMA tests, the dependency in terms of temperature for the real component of the complex elastic modulus (E′), the imaginary component of the complex elastic modulus (E″), as well as tan(δ) can be traced. For a more efficient use of the composite materials, the compliance tensor was obtained with nondestructive tests based on ultrasound. A method for the generation and reception of Lamb waves in plates of composite materials is described, based on using air-coupling, low-frequency, ultrasound transducers in a pitch–catch configuration. The results of the nondestructive measurements made in this study are in good agreement with those obtained when using the DMA destructive tests.

Analysis of a Composite Blade Design for 10 kW Wind Turbine Using a Finite Element Model

This paper presents the final design of glass-reinforced polyester (GRP) blade for 10 kW wind turbine developed at the Technical University of Moldova by finite element (FE) analysis techniques. This design was reached through an iterative analysis process following a previous design. The objective of this research is to maximize structural robustness of composite blade while reducing its mass and cost. Design optimization of the composite wind turbine blade was performed by checking the static and dynamic behavior. The design variables considered are related to the composite material parameters: fiber direction, layups direction and blade shell thickness based on number of composite layers. The constraints are tip deformations, allowable stresses and resonant vibration of the blade. According to FE analysis results the optimized blade will be stiff enough in storm conditions, will operate out of dangerous resonance frequencies and will weigh approximatively 20% less.

Failure strain and stress fields of a chopped glass-reinforced polyester under biaxial loading

We perform experimental tests to obtain biaxial stress states in a chopped glass-reinforced polyester composite, applying in-plane perpendicular tensile loads to cruciform specimens. Three different specimens’ geometries have been considered for obtaining adequate failure modes with different loading cases. The scope is to estimate the strain and the stress failure states by measuring with gages the strains developed in the central zone, where a plane stress state with zero shear component occurs. We develop numerical simulations using the Finite Element Method in order to achieve a better understanding of the behaviour of the cruciform specimens under loading and to compare the numerical results with the experimental data. Maximum stress, Maximum strain, Tsai-Hill and Tsai-Wu biaxial failure theories are evaluated for the assumption of isotropic behaviour and contrasted with the experimental results.

Low-velocity impact behavior of CNF-filled glass-reinforced polyester composites

A significant improvement in fiber-reinforced polymeric composite materials can be obtained by incorporating a very small amount of nanofillers in the matrix material. In this study, an ultrasonic liquid processor was used to infuse carbon nanofibers into the polyester matrix which was then mixed with a catalyst using a mechanical agitator. Both conventional and carbon nanofibers-filled glass fiber-reinforced polyester composites were fabricated using the vacuum-assisted resin transfer molding process. Low-velocity impact tests was performed at 10 J, 20 J, and 30 J energy levels on conventional as well as 0.1–0.3 wt% carbon nanofibers-filled glass fiber-reinforced polyester composites using Dynatup8210. The morphology of fractured specimens was examined using digital photographs and optical microscopy. There was an increase in the peak load for the nanophased glass fiber-reinforced polyester composites compared with the conventional one. The absorbed energy of nanophased glass fiber-reinforced polyester composites was less than that of conventional one at different energy levels. The extent of damage was more pronounced in the conventional glass fiber-reinforced polyester composites compared to nanophased ones. Failure mechanisms comprised of indentation, debonding, delamination, matrix cracking, and fiber fracture. The extent of damage was pronounced in conventional composite compared to nanophased ones.

Experimental and theoretical investigations on the failure of filament wound GRP pipes

Usually, Glass Reinforced Polyester (GRP) pipe industry uses simple netting analysis to predict longitudinal and apparent hoop tensile strengths during structural design procedure. Along the simplicity of this method, it underestimates/overestimates the strengths resulting in over designed and expensive pipes or unqualified pipes. A sequential failure modeling which is suitable for laminated composites with quartz sand core is developed to overcome this difficulty. A computer code is written to calculate mentioned strengths using winding angles, number of layers and sand ratio as the main input parameters. A comparative study is performed between results obtained by netting analysis and developed sequential failure modeling. A complete set of experiments have been carried out on different ranges of diameters and pressure classes of GRP pipes to determine the suitability of developed method. It is observed that developed modeling for GRP pipes with sand filler predict strengths of pipes with high level of accuracy.

Failure envelope under biaxial tensile loading for chopped glass-reinforced polyester composites

In this paper we present the biaxial failure curve of a chopped glass-reinforced polyester composite. The curve has been obtained combining the results of experimental tests with the results of numerical simulations developed by means of the Finite Element Method. The experimental tests have been performed applying perpendicular loads to cruciform specimens. Then, taking into account the numerical results, we have constructed the failure envelope in the tensile–tensile quadrant. Moreover we propose to modify the cruciform geometry to obtain, varying the widths of the loaded arms and the tapered central zone, points of the failure curve in which the two components of the plane stress tensor are different.

Effect of reinforcement type on high velocity impact response of GRP plates using a sharp tip projectile

High velocity impact performance of glass reinforced polyester (GRP) resin composite plates with different type of reinforcement was investigated. The projectile used was a sharp tipped (30°) conical head with total length of 30 mm and shank length of 15 mm with weight of 9.74 g. Five different types of E-glass fiber reinforcement were used, including chopped strand mat (CSM), plain weave, satin weave, unidirectional and cross-ply unidirectional fiber reinforcements. A smooth barrel gas gun was used to conduct high velocity impact tests in the velocity range of 80–160 m/s. Composite plates with size of 15 cm × 15 cm were prepared in 3 and 6 mm thickness. Results showed higher ballistic limit velocity (velocity at which samples fully penetrated the target plates with zero residual velocity) for 3 mm GRP plates with cross-ply unidirectional reinforcement followed by unidirectional reinforcement and plain weave, the plates with satin weave and CSM reinforcements were almost in same level. The thicker specimens (6 mm), plates with plain weave reinforcement showed better ballistic performance towards sharp tipped conical projectile impact, followed by cross-ply unidirectional, satin weave, unidirectional and CSM reinforced plates. Experimentally determined ballistic limit velocity for all specimens correlate well with estimated ballistic limit values obtained in full perforation tests. Damage assessment conducted on all specimens indicated fiber tension and shear failure for thin-walled and sever delamination for the thick-walled specimens as the dominant failure modes.

Suppress flashover of GRP fire with water mist inside ISO 9705 Room

Water mist suppression tests for glass-reinforced polyester (GRP) panels were conducted in ISO 9705 Room. GRP panels covered part of the room and a wood crib fire was used as fire source to ignite GRP fire. A four-nozzle water mist suppression equipment was used inside test room on the time of flashover. Heat release rate of the combustion inside the room, room temperature, surface temperature of GRP panels, total heat flux to wall, ceiling and floor in specific positions were measured. Gas concentration of O2, CO, and CO2 was also measured in the corner of the room at two different levels. A thermal image video was used to record the suppression procedure inside room. Test results show that the water mist system is efficient in suppressing the flashover of GRP fire and cooling the room within short time.