Scipedia: Open Access Repository of the FIBRESHIP project

Cost-benefit analysis tools

Julio García-Espinosa — Wed, 03 Jun 2020 18:52:03 +0200

The objective of the present report D8.2 in relation with Task 8.3 in Work Package 8 was to provide cost benefit analysis support to FiBRESHiP partners throughout to entire project in the technical work packages related to the analysis of large-length fibre-based commercial vessels (FRP) such as the three types targeted in the project: container ship, Ro-Pax, and Fishing Research Vessel (FRV) and to benchmark them with conventional steel (BAU) vessels. Technical decision support with cost-benefit analysis included production, operation and dismantling of the above mentioned vessels of the same size by using NPV, RRI and ROI calculations, with the reflection of operational costs in fuel saving due to weight reduction. The deliverable reflects to the needs of industry stakeholders by revealing cost-benefit information and concludes with the financial comparison between conventional (steel) and FRP vessels.

Mechanical characterization of polymer composite materials for long length ships

Amit Kumar Haldar — Mon, 11 May 2020 12:20:04 +0200

In the marine industry, Fibre-reinforced polymers (FRP) are currently dominating the manufacture of vessels up to 50m in length, with liquid resin infusion (LRI) being the most frequently used manufacturing technique, of which vacuum-assisted liquid resin infusion is the most widely adopted LRI variant. However, current regulations restrict the use of composite materials in vessels over 50m in length. FIBRESHIP is a Horizon 2020 funded EU project that aims to further the use of FRPs in vessels over 50m in length by addressing the regulatory restrictions and the numerous other challenges associated with manufacturing long-length FRP composite ships. The mechanical performance of new commercially available composite material constituents as potential candidates for selection in composite ship construction is central to this work. This paper provides an overview of selected work performed as part of the FIBRESHIP project in terms of evaluating various mechanical properties of selected laminates under dry and wet conditions. The laminates were immersed in seawater at 35°C for durations of one to three months. Three-point bend and interlaminar shear strength tests were undertaken in order to investigate the change in the mechanical properties of composite laminates subject to immersion. Finally, tested specimens were observed using micro-computed tomography (μCT) to evaluate the failure morphology.

Report and database on the results of the fire performance experiments

Julio García-Espinosa — Fri, 15 May 2020 10:02:02 +0200

Today, fibre reinforced polymer (FRP) materials are extensively used for building lightweight hull structures of vessels with length up to about 50 metres, whereas in longer vessels their use is limited to secondary structures and components. In the European FIBRESHIP research project, innovative FRP materials are evaluated, new design and production procedures and guidelines are elaborated, and new validated software analysis tools are developed. As a result of the project, a comprehensive set of methods will be compiled, enabling the building of the complete hull and superstructure of over 50-metre-long ships in FRP materials. The results enhance significantly the use of FRP materials in shipbuilding and strengthen the competitiveness of the European shipbuilding industry on the world market.

In Task 2.4 of the FIBRESHIP project, an extensive experimental campaign was performed in two phases to characterize the fire performance of FRP materials and solutions.

For the first phase, seven commercially available resins or resin systems were selected for examination of fire performance. Laminates with glass fibre reinforcement and cured resins without reinforcement were produced for cone calorimeter tests and thermogravimetric analyses, respectively. From these seven candidates, two materials were down-selected on the basis of the mechanical performance, manufacturability and impact (including cost, claimed fire retardancy, worker health impact and recyclability).

The two material solutions chosen to continue to the second phase were LEO vinylester resin system and SR1125 epoxy resin system. The fire tests of the first phase showed that an intumescent coating on the surface of these laminates is essential for providing adequate fire performance.

In the second phase, a more comprehensive evaluation of thermal and fire properties was performed by carrying out more cone calorimeter tests, as well as dynamic mechanical thermal analysis, microscale combustion calorimetry, differential scanning calorimetry and transient plane source tests. Simultaneously, data for pyrolysis modelling, thermomechanical modelling and fire simulation was produced.

In cone calorimeter test at the irradiance of 50 kW/m2, the times to ignition of coated LEO and SR1125 were 75 and 52 seconds on the average, respectively. The maximum heat release was 261 kW/m2 for SR1125, but only 69 kW/m2 for LEO indicating good reaction-to-fire performance. The total heat release and the total smoke production were ca. 40 MJ/m2 and 9 m2, respectively, for both systems.

Cone calorimeter tests of coated laminate specimens were run also at the irradiance levels of 25 and 35 kW/m2 and for specimens representing different production batches. The results were not consistent in all cases. In addition, DSC tests revealed changes of the glass transition temperature when the specimens were re-heated, referring to incomplete curing in the manufacturing process. These observations highlight the importance of repeatable and well- controlled manufacturing process. The whole process must be carefully instructed, monitored and reported. The laminates and coatings must be of uniform quality to ensure the fire performance claimed on the basis of fire tests performed. Precise specifications and quality control play a key role in securing the fire safety of materials and products.

Thermogravimetric analyses and micro-scale combustion calorimetry showed that the mass loss of cured resins typically starts slightly above 300 °C both in inert (N2) and oxidative (air) atmosphere. The reactions in these atmospheres differ, the oxidative atmosphere revealing reactions such as char oxidation. At about 300 °C, however, a structure made of these FRP materials starts to produce combustible gases and contribute to fire.

Dynamic mechanical thermal analysis showed that the glass transition temperature is ca. 111 °C for LEO, and ca. 95 °C for SR1125. In general, the glass transition temperatures of FRP materials are typically about 100 °C. At this temperature, the material softens and loses its loadbearing capacity.

Structures made of FRP materials have a tendency to heat up locally, due to their relatively low thermal conductivity. In the case of a local fire, combustible gas production and heat release are the main concerns in terms of fire safety. If the fire threatens a large structure, like in the case of a compartment fire, the main problem is the softening of the material and the loss of the loadbearing capacity.

Experimental Investigation on the effect of thickness on the flexural properties of glass/vinyl-ester composite laminates for marine applications

Anthony Comer — Mon, 11 May 2020 21:21:02 +0200

Fibre-reinforced polymer (FRP) composite materials find increasing acceptance and application in a

number of transport sectors (aviation, land & waterborne transport) due to their lightweight nature, which

provides a significant advantage in terms of lower fuel consumption and greenhouse gas emissions, in line

with relevant EU directives. Particularly in waterborne transport and shipbuilding, FRP composites are

currently dominating the manufacture of vessels up to 50 m in length, with liquid resin infusion (LRI) being

the most frequently used manufacturing technique and vacuum-assisted resin transfer moulding (VARTM)

in particular the most widely adopted LRI variant. The wide-scale adoption of FRP composites into large

marine structures is often hindered by the lack of guidelines available for qualification of these materials

by classification societies. FIBRESHIP is a Horizon 2020 funded EU project that aims to further the use of

FRP composites in long-length ship construction by addressing this issue in addition to tackling numerous

other challenges associated with manufacturing FRP composite ships. This work represents part of a

selection process for materials for the construction of long-length ships from FRP composites and focuses

on a commercially available fire-retardant composite system (SAERTEX LEO®). As part of the selection

procedure for these materials, material properties, such as the flexural strength and modulus, are obtained

using coupon-sized test-pieces and are subsequently used as the basis for numerical models for ship design.

However, the actual material that is used in the final ship structure is significantly thicker than the coupons

from which the original material properties were derived. Additionally, the scale of the manufacturing

process of laminates for the extraction of coupons is drastically different to that of the manufacturing

process of a ship’s hull. The aim of the study is, therefore, to compare the flexural properties obtained from

a thin monolithic laminate manufactured in a research laboratory (University of Limerick, Ireland) to the

flexural properties obtained from a thick monolithic laminate representative of the thickness of a ship hull

manufactured in a shipyard (iXBlue Division H2x, Marseille, France) using the same material under

investigation. This will give an indication of how representative the thin test coupons are of the material

manufactured by the shipyards at the thickness used in the final structure. Unidirectional laminates are

manufactured in both the research and shipyard facilities by VARTM using the Saertex LEO Glass/Vinyl

ester system (the system includes a fire-retardant gel coat, however the gel coat was not applied for the

purpose of obtaining the mechanical properties of the FRP component of the system only). Dynamic

Mechanical Analysis (DMA) is performed on specimens from the thin and thick laminates to establish that

the laminates have been fully cured. Three-point-bend tests in accordance with ISO 14125 are performed

on 0° and 90° specimens extracted from thin and thick laminates. Another set of 0° and 90° specimens

extracted from thin and thick laminates are tested according to Bureau Veritas guidelines (NR456) in order

to investigate the comparison between the properties obtained using both methods. Fracture mechanisms in

thick and thin specimens are examined using scanning electron microscopy.

Experimental Investigation on the effect of water ingress on the flexural and interlaminar properties of glass/vinylester composite for marine applications

Anthony Comer — Mon, 11 May 2020 21:44:02 +0200

Fibre-reinforced polymer (FRP) composite materials find increasing acceptance and application in a number of transport sectors due to their lightweight nature, which provides a significant advantage in terms of lower fuel consumption and greenhouse gas emissions, in line with relevant EU directives. Particularly in the marine industry, FRPs are currently dominating the manufacture of vessels up to 50 m in length, with liquid resin infusion (LRI) being the most frequently used manufacturing technique and vacuum-assisted resin transfer moulding (VARTM) in particular the most widely adopted LRI variant. The wide-scale adoption of FRPs into large marine structures is often hindered by the lack of guidelines available for qualification of these materials by classification societies, particularly in relation to fire safety. FIBRESHIP is a Horizon 2020 funded EU project that aims to further the use of FRPs in long-length ship construction by addressing this issue in addition to tackling numerous other challenges associated with manufacturing FRP composite ships. It is important to characterise fully the performance of new commercially available marine resin systems as a potential candidates for selection in composite ship construction. This needs to be done under a wide range of environmental conditions, as durability of composites and their ability to exhibit unchanged performance and stability in a marine context and environment is a crucial factor in their selection. Ideally, a composite would retain its mechanical and thermo-mechanical profile even when exposed to a marine environment for extended periods. During the service life of marine composites (typically 20-25 years), water uptake is inevitable. This may cause plasticization, swelling, matrix hydrolysis or debonding of fibres from the matrix. As a result, the mechanical and thermal properties degrade accordingly, and the service life is shortened. This work represents part of a selection process for materials for the construction of long-length ships from FRPs and focuses on a commercially available fireretardant composite system (SAERTEX LEO®). The aim of the study is, therefore, to compare the flexural (ISO 14125) and interlaminar shear (ISO 14130) properties of the SAERTEX LEO® composite system under dry conditions and under “wet” conditions where the specimens have been immersed in deionised water at 35°C for varying durations (28 days, two months, three months). The flexural and interlaminar properties will also be assessed after soaking for 28 days, two months and three months followed by a drying process to remove all ingressed water. This will give an indication of the reversibility of the effects of water ingress and highlight the point at which permanent alteration of the properties begins to occur. Unidirectional laminates are manufactured by VARTM using the Saertex LEO Glass/Vinyl ester system (the system includes a fire-retardant gel coat, however the gel coat was not applied for the purpose of obtaining the mechanical properties of the FRP component of the system only). Dynamic Mechanical Analysis (DMA) is performed to establish that the laminates have been fully cured and fracture mechanisms are examined using scanning electron microscopy.

Materials for large length fibre-based ships. Characterization, selection, and numerical analysis

Joel Jurado Granados — Wed, 13 May 2020 18:51:02 +0200

Fourth dissemination action for university students for increasing the interest in the use of fibre-reinforced polymers for large-length vessels design and shipbuilding in the future naval architects and marine engineers. This presentation was held at the School of Naval Architecture and Ocean Engineering (ETSINO) of the Technical University of Madrid on the 1st of October of 2019. In this presentation, the process of materials selection for marine applicactions and the numerical models for characterizing and predicting the fatigue and failure of such materials were introduced.

FIBRESHIP Presentation delivered to academics, students and researchers at the "Composites at Bernal Seminar Series", Bernal Institute, University of Limerick, April 2019

Anthony Comer — Thu, 14 May 2020 22:51:02 +0200

Presentation given to Academics, students and researchers at the "Composites at Bernal Seminar Series", Bernal Institute, University of Limerick

Numerical tools for the design of fibre-based ships of large lengths

Joel Jurado Granados — Wed, 13 May 2020 18:36:03 +0200

First dissemination action for university students at the School of Naval and Ocean Engineering (ETSINO) of Cartagena University (UPCT) with the intention of increasing the interest of the students and future engineers and naval architects in the use of composite materials for the design and shipbuilding of large-length vessels. In this presentation, the numerical models developed for predicting the fatigue and failure of composite materials were showed. Besides, the new numerical tools to design and anayze fiber-based ships of large length were introduced, specifically a coupled seakeeping-FEA tool, a new graphical user interface (GUI) for materials definition, hull girder analysis and collapse assesemt.

Mechanical evaluation of a fire retardant through-thickness reinforced sandwich structure for marine applications

Anthony Comer — Fri, 08 May 2020 22:59:02 +0200

One of the main restrictions in adopting polymer composite materials for primary and secondary structural applications in marine vessels over 50 meters in length is concerns regarding fire retardancy and also a lack of design guidelines in general. The aim of this study is to evaluate the edgewise compression strength and core-shear strength of a fire retardant sandwich structure reinforced with through thickness composite ‘bridges’ under ambient conditions. These properties are important for structural components subjected to in-plane loads such as bulkheads. Core shear strength of the through-thickness reinforced sandwich far exceeded non-reinforced sandwich. However, edgewise compression strength and stiffness of the reinforced case was found to be similar to the unreinforced case.

Retention of Mechanical Properties After Water Immersion for Glass-Fibre Polymer Composite Laminates with Thermoset & Thermoplastic Infusible Resins

Anthony Comer — Mon, 11 May 2020 22:24:02 +0200

Glass-fibre reinforced polymer (GRP) composite materials are the most widely adopted amongst fibrereinforced polymer composites globally, with approximately 1 million tons produced annually in the EU alone. GRP’s find very wide use and application in a number of industrial sectors (e.g. land & waterborne transport1 , marine, construction) due to their excellent balance between good performance and low cost compared to fibre reinforced polymers utilising other commercially available fibres (e.g. carbon, aramid). Particularly in marine applications, durability of composites and their ability to exhibit unchanged performance and stability in a marine context and environment is a crucial factor in order to select the most appropriate combination of polymer matrix and reinforcement. Ideally, a composite would retain its mechanical and thermo-mechanical profile even when exposed to a marine environment for extended periods. In this work, we conducted an extensive comparative study of the water absorption behavior and retention of mechanical properties of a group of GRP composite laminates manufactured with a range of infusible thermosetting and thermoplastics resins. Sample preparation for water immersion studies was according to ASTM D5229. This study was part of a comprehensive down-selection of commercially available resins in terms of their suitability for shipbuilding applications, as part of the EU H2020 project FIBRESHIP2 . All laminates were manufactured by Vacuum-Assisted Resin Transfer Moulding (VARTM; the most relevant manufacturing technique in shipbuilding) with a range of state-of-the-art thermosetting resins (Urethane acrylate Crestapol 1210, Epoxy SR1125, Bio-epoxy Supersap CLR, Phenolic Cellobond J2027X) and a novel infusible acrylic thermoplastic resin (Acrylic Elium 150). The reinforcement of choice for each laminate was a unidirectional glass fabric of 996 gsm. A selection of relevant properties of the laminates with different resin systems is presented in this paper including fibre volume fraction, apparent interlaminar shear strength (dry and wet condition), flexural strength (dry and wet condition) and flexural modulus (dry and wet condition). For the wet condition, samples were immersed in distilled water for 28 days at 35 oC (wet state) in accordance with classification society guidelines. The quality of the laminates (void content, fibre-matrix adhesion) was examined by scanning electron microscopy on fracture surfaces. The effects of water absorption on the microstructure, mechanical, thermal & thermomechanical properties of the laminates were studied. The average water absorption percentage varied across all resins systems from 0.19 to 1.37% in the interlaminar-shear specimens, and from 0.25 to 1.59% in the flexure specimens. The phenolic laminate was the one absorbing most water in both cases but the mechanical properties were relatively unaffected. Fibre volume fraction was in the range 0.56 to 0.6 for all of the laminates. The majority of the tested GRP laminates showed good retention of their flexural properties and interlaminar shear strength under the testing conditions. The laminate that appeared to be most adversely affected was the infusible thermoplastic, showing a reduction in flexural strength and interlaminar shear strength of 17.3% and 37.5%, respectively (in comparison to the dry state values). However, the water absorption for the Elium 150 was not excessive, ranging from 0.40 to 0.42% for the ILSS and flexure samples, respectively.

References: 1 Summerscales J, Marine applications of advanced fibre reinforced composites, Woodhead Publishing, Cambridge, 2016 2 H2020 project FIBRESHIP, funded by the European Commission under GA 723360 (www.fibreship.eu)

Effect of Environmental Conditioning on the Properties of Thermosetting and Thermoplastic-Matrix Composite Materials by Resin Infusion for Marine Applications (PREPRINT)

Anthony Comer — Tue, 12 May 2020 13:19:02 +0200

Glass-fibre reinforced polymer (GFRP) laminates were manufactured using Vacuum assisted Resin Transfer Moulding (VaRTM) with a range of thermosetting resins and a novel infusible thermoplastic resin as part of a comprehensive down-selection to identify suitable commercially available resin systems for the manufacture of marine vessels greater than 50 m in length. The effect of immersion in deionised water and in an organic liquid (diesel) on the interlaminar shear strength (ILSS) and glass transition temperature (Tg) was determined. The thermoplastic had the highest Tg of all materials tested and comparable ILSS properties to the epoxy. Immersion in water, however, caused larger reductions in ILSS properties of the thermoplastic compared to the other systems. SEM showed a transition from matrix-dominated failure in the dry condition to failure at the fibre-matrix interface in the wet and organic-wet specimens. The overall performance of the infusible thermoplastic is good when compared to well-established marine resin systems; however, the environmental performance could be improved if the thermoplastic resin is used in conjunction with a fibre sizing that is tailored for use with acrylic-based resin systems.

Numerical Simulation of Fatigue in Composites

Joel Jurado Granados — Tue, 12 May 2020 17:07:03 +0200

For the past several years, composite marine structures have been designed but without having a complete characterization the composite materials. The main reason is due to the large quantity of variables that affect the behavior of said materials. One of the tasks that has not been properly characterized is the behavior of composite structures under fatigue loads that appear in marine structures that are subjected to cyclic loads. Therefore, numerical tools that characterize fatigue performance are required in order to design more reliable structures. The formulation proposed in this work is based on the Serial/Parallel Rule of Mixtures [1] and a fatigue damage model [2]. The Serial/Parallel Rule of Mixtures can be understood as a constitutive law manager that provides the response of the composite from the constitutive performance of its constituents. Therefore, the constitutive laws chosen to represent the behavior of each constituent material have to fit with their real performance. Also, the fatigue damage model is based on the use of a reduction function which takes into account the cyclic degradation of the materials, both strength and stiffness degradation, in function of the number of cycles, maximum stress and stress amplitude. Current work presents a numerical tool developed to characterize fatigue in composites. The fatigue behavior of constituent materials is defined using mechanic parameters taken from literature. Afterwards, a reproduction of the tests will be done in order to validate the fatigue formulation proposed.

[1] Car, E., Oller, S., Oñate, E. "Estudio del comportamiento no lineal en materiales compuestos", Techincal Report 264,CIMNE, 1997.

[2] Oller, Salomon, O., Oñate, E. “A continuum mechanics model for mechanical fatigue analysis", Composite Materials Science, Vol 32, Issue 2, pp 175-195, 2005.

Numerical and experimental procedure for material calibration using the serial/parallel mixing theory, to analyze different composite failure modes

Joel Jurado Granados — Tue, 12 May 2020 16:06:02 +0200

This work proposes a calibration procedure to obtain the material parameters required by the Serial/Parallel Mixing Theory for the analysis of composites. A set of experimental tests are defined to obtain the main composite failure modes. Then, it is proposed to calculate the parameters required by the formulation using the experimental results. The procedure proposed is validated by comparing the numerical results, with those obtained from the experimental campaign. This comparison shows that the Serial/Parallel mixing theory is capable of representing the failure modes of the composite for different loading scenarios as well as the material toughness.

2nd FIBRESHIP WORKSHOP - Overall description of the FIBRESHIP project

Julio García-Espinosa — Mon, 08 Jul 2019 20:04:33 +0200