C. Santulli

University of Camerino | UNICAM · Scuola di Architettura e Design

The present study investigates mode I interlaminar fracture toughness of aramid/epoxy, carbon/epoxy and intra-ply hybrid composites, obtained from carbon and aramid fibres as the reinforcement of an epoxy matrix, maintaining the total fibre content equal to 50 wt.%. The bidirectional, woven fabric specimens were fabricated using vacuum moulding tec...

The wind energy market requires reliable wind turbines with a long and efficient working life, able to generate energy without interruption, at the lowest investment and operating cost. The current material systems used for making wind turbine blades are in majority based on glass fibres and epoxy resins. These thermoset polymer composites with syn...

The design of composite components in the aerospace industry often includes structural discontinuities, such as cutouts, for functional requirements like ventilation, tunnel passage, maintenance and repair. The presence of cutout holes leads to complicated stress concentrations with a substantial reduction in structural stability and strength of th...

A new composite material, defined as Ductile High Energy Composite (DHEC), is analysed in this paper, with particular reference to the energy absorbed after high speed impacts and to the relevant failure mode. A set of DHEC and pure carbon fibre laminates presenting equal weight, equal bending strength or equal stiffness, respectively, have been co...

Structural components of composite materials in aerospace industries are assembled using fasteners, installed by performing cutting processes, such as drilling, on the material. In composites, this is considered particularly critical, because delamination due to mechanical stresses and fiber/resin pullout may be facilitated during cutting, so that...

The use of recycled paper in HDPE (High Density PolyEthylene) matrix composites has recently been introduced as an interesting alternative to traditional recycling process for paper. HDPE is also used as double wall greenhouse glazing because panels are easy to install, UV stabilized, and affordable. These type of products must also be strong enoug...

This paper focuses on the experimental investigation of impact damage resistance in hybrid composite laminates. In this case, the low velocity impact behaviour of quasi-isotropic glass/epoxy, glass/basalt/epoxy (G/B/G, B/G/B) and glass/carbon/epoxy (G/C/G, C/G/C) composite laminates was simulated by carrying out quasi-static indentation (QSI) tests...

Ternary hybrids including carbon, basalt and flax fibres in an epoxy matrix have been fabricated by hand lay-up, then consolidated by vacuum bagging using two different stacking sequences. Both configurations involved the use of carbon fibres on the outside, whilst basalt and flax fibres were disposed internally either in a sandwich or in an interc...

In this work, three different types of laminates, each one realized with thirteen layers of fabric in epoxy matrix, have been inspected. In the first one, only aramid fiber is used, whilst the other two are hybrid laminates reinforced with basalt and aramid fibers disposed either in an intercalated or in a sandwich-like structure. All laminates wer...

In this work, the use of advanced thermographic techniques for the postimpact defect detection in basalt fibre reinforced composite laminates was investigated. The laminates were previously impacted at different energies, namely 7.5, 15 and 22.5 J and then subjected to accelerated environmental aging or to a coating process in order to conceal the...

Short fibre based cotton flocks from end-of-life jeans fabric (denim twill weave) were introduced in an amount of 16 wt.% in a polypropylene (PP) matrix using a specifically designed manufacturing process to preserve as much as possible the properties of the cotton waste during injection moulding. This involved a first phase of binding the cotton f...

This paper investigates the individual and associated effects of post cure-temperature and reinforcement phases on the local bending response of adhesive reinforced repairs in damaged glass/epoxy composite laminates. Multiple quasi-static indentation tests were performed on repaired composite laminates: damage propagation, absorbed energy and resid...

Voids in composites have been a perennial problem, since the amount of porosities is deemed to bear a strong relation with the degradation of service performance of laminates. On the other side, the effect of porosity on impact resistance of laminates is often dependant on their distribution in the material, especially with respect to the location...

Studies of the combined effects of the presence of porosity (as it may result from partially effective cure cycles) and of low-energy impact damage on the residual properties of CFRP laminates have led so far to controversial results. In particular, it is not clear from the literature whether the presence of voids would blunt crack propagation foll...

The impact and flexural post-impact behaviour of ternary hybrid composites based on epoxy resin reinforced with different types of fibres, basalt (B), flax (F), hemp (H) and glass (G) in textile form, has been investigated, namely FHB, GHB and GFB. The reinforcement volume employed was in the order of 21-23% throughout. Laminates based exclusively...

This chapter discusses the use of acoustic emission (AE) as a useful tool for mechanical behaviour monitoring and characterization of natural fibre composites. The chapter begins by providing a detailed overview of non-destructive techniques and the principles of the (AE) method. It then reviews the instrumentation and analysis of (AE) data, with p...

Multifunctional nanocomposites based on polymeric matrices and natural fillers such as nanocrystalline cellulose (NCC), microfibrillated cellulose (MFC) and bacterial cellulose (BC), are of scientific and industrial interest for their notable performance improvement. Moreover, cellulosic nanoreinforcements have recently attracted much attention due...

The effect of temperature on the low velocity impact resistance properties and on the post-impact flexural performance of CFRP laminates were studied. With this aim, 150 x 75 mm cross-ply carbon fibre/epoxy laminates with a [0/90/90/0](2s) layup, therefore with a total of sixteen layers, were impacted at ambient temperature (30 degrees C) and at el...

This paper investigates the effect of impact velocity on compression-after impact (CAI) strength, while the different failure modes arising during CAI test are characterized using the acoustic emission (AE) technique. For this purpose, CAI GFRP laminates manufactured as per ASTM D7137 were subjected to impact velocities such as 3.5, 5 and 6 m/s at...

This paper reports on the promising perspectives of using keratins extracted by sulphitolysis reaction from Merino wool (KM) and Brown Alpaca fibres (KA) in poly (l-lactide) (PLLA)-based biomaterials. Both types of keratin were dispersed in chloroform (CHCl3) and tetrahydrofuran (THF), and optimisation of dispersion methods and parameters using the...

During the last decade, interest in using natural fibre reinforced composites has increased due to their good specific mechanical properties. The results of an experimental study of the influence of temperature and impact velocity on the low velocity impact response of jute fiber reinforced unsaturated polyester (UP) composite laminates is presente...

The need to fi nd environmentally friendly alternatives to traditional synthetic fi bres such as glass fi bres to be used as reinforcement in polymer matrix composites has attracted a growing interest in natural plant fi bres in the last decade. In this regard, this chapter provides a comprehensive overview on a less common, but promising, natural...

The aim of this study is to investigate the effect of low-velocity multiple impacts at ambient (35℃) and elevated temperature (65℃ and 85℃) on unidirectional glass fiber reinforced plastic (GFRP) composites. Low-velocity repeated impact tests were conducted using a falling weight tower at a constant velocity of 1.5 m/s. The dominant parameters such...

Unidirectional (0 degrees) and cross-ply (0/90) carbon-epoxy laminates were subjected to falling weight impact loading with energy of 2.17 J, therefore not producing visible damage, at different temperatures (30, 55, 75 and 90 degrees C). Post-impact flexural tests were monitored using acoustic emission (AE). Both for unidirectional and 0/90 lamina...

Résumé Ce travail a pour but d’étudier la résistance à l’impact mécanique d’un composite à renfort de chanvre et matrice époxy, ainsi que l’influence de l’endommagement sur sa résistance en traction quasi-statique et en fatigue. Le composite étudié est constitué de 7 plis de renfort tissé de chanvre et le taux volumique de renfort est de 30%. Les...

Composite laminates have low resistance under dynamic loading, particularly impact loading. A low-velocity impact on laminated composites causes various types of damage, such as delamination, fibre breakage, matrix cracking and fibre matrix interfacial debonding. Post-impact compressive strength is one of the greatest weaknesses in carbon fibre rei...

This chapter discusses the use of vinylester resin as a matrix in polymer composite materials to be used in civil engineering applications. The chapter begins by discussing the increasing trend of composite development and use in civil engineering along with the related reasons. It then reviews the chemistry of vinylester resins together with their...

In this work, type 2024-O aluminium from ALCOA with a nominal thickness of 0.5mm was stacked on both sides of a hemp polypropylene composite with stacking sequence 1Al/10PP/1H/10PP/1Al. Tensile and planar indentation loading of the fibre-metal laminates so obtained have been followed in real time using acoustic emission monitoring and related to da...

The use of natural fibres for the reinforcement of polymers is a well-established practice: the biocomposites obtained with this procedure are increasingly used in sectors, such as automotive and construction industries. In particular, green composites represent a class of biocomposites increasingly emerging in polymer science: these are characteri...

The disintegration patterns of composites produced by a melt compounding process using 0, 20, 30, and 40 wt % of Phormium tenax fibers in poly(lactic acid) (PLA) matrix were studied for a period of 40 days in composting conditions. The characterization of PLA and PLA/phormium composites included disintegration measurements, differential scanning ca...

This paper presents the results of an experimental investigation conducted to study the strength of different repair technique on impact damaged glass fibre reinforced plastics (GFRP) using the acoustic emission technique. ASTM D3039 tensile specimens (250 mm × 18 mm × 2 mm) fabricated using bi-directional glass fibre and epoxy resin are impacted a...

The addition of small amounts (up to 9 wt%) of chitin microsized particles, originating from shellfish waste, to carboxylated styrene-butadiene rubber (XSBR) matrix (as received and annealed to 100°C) has been studied. In particular, this study concentrated on their mechanical (creep investigation by nanoindentation and dynamical-mechanical analysi...

Acoustic emission (AE) is widely used to characterize damage occurring in composite materials: however, the discrimination between AE signatures due to different damage mechanisms is still an open issue. In this study, the various failure mechanisms in bidirectional glass/epoxy laminates subjected to uni-axial tension are identified using AE monito...

Cellulose nanocrystals (CNC) were extracted from okra bahmia (Abelmoschus Esculentus) bast fibers and inserted in different tenors (1, 2, 5, and 10 wt %) as the reinforcement of a poly(vinyl alcohol) (PVA) matrix. The extraction of cellulose was carried out in a two-step procedure: the first chemical treatment led to the production of holocellulose...

This work concerns the production by vacuum infusion and the comparison of the properties of different hybrid composite laminates, based on glass, flax and hemp fibers in different combinations, keeping constant basalt laminates as the inner core of the layered material and a 21±1% fibers volume throughout. The laminates have been subjected to tens...

Acoustic emission is a technique which has shown over the years a significant potential in damage assessment on polymer composite materials. In the specific case of impact damage, the very short time, during which the impact event takes place, does not allow in most cases a direct application of this technique for real time test monitoring. However...

Composites of Phormium tenax fibres in a polypropylene matrix with fibre content up to 40 wt%, produced by injection moulding and twin screw compounding, have been characterized by scanning electron microscopy, differential scanning calorimetry, thermogravimetric analysis and mechanical test. The results have shown that the main degradation peak fo...

Acoustic emission (AE) can be used for in situ structural health monitoring of the composite laminates. One of the main issues of AE is to characterize different dam-age mechanisms from the detected AE signals. In the present work, pure resin and GFRP composites laminates with different stacking sequences such as 0°, 90°, angle ply[±45°], cross-ply...

Composites that include plant fibres have been used more and more in large-volume applications recently, with a view to obtaining a more environmentally friendly material than fibreglass. However, there are serious concerns about the reliability of their mechanical properties. In this regard, the use of acoustic emission to monitor monotonic mechan...

Composites of Phormium tenax fibers in a poly(lactic acid) matrix with fiber content of up to 40 wt%, produced by injection molding and twin screw compounding, were characterized by scanning electron microscopy, differential scanning calorimetry, thermogravimetric analysis, and mechanical tests (static and dynamic). Thermal analysis showed that col...

The various failure mechanisms in bidirectional glass/epoxy laminates loaded in tension are identified using acoustic emission (AE) analysis. AE data recorded during the tensile testing of a single layer specimen are used to identify matrix cracking and fiber failure, while delami-nation signals are characterized using a two-layer specimen with a p...

The tensile and impact properties of environmental-friendly composites and FMLs have been investigated. Of the four composites investigated here, a SRPP composite offered superior properties to basalt-, flax-, and hemp fiber-reinforced PP composites. Adding aluminum layers to the outer surfaces of the composites resulted in a significant enhancemen...

Acoustic emission (AE) can be used for in situ structural health monitoring of composite laminates. One of the main issues of AE is to characterize the different damage mechanisms from the detected signals. With these aim, glass/epoxy cross-ply laminates, fabricated using vacuum bag molding, were subjected to uni-axial tensile test under AE monitor...

The objective of this study is to characterize the tensile properties of New Zealand flax (Phormium tenax) technical fibers to be used as potential reinforcement in polymer matrix composites. Single fiber tensile tests were performed at three gage lengths to assess the effect of gage length on tensile strength and Young’s modulus. The results were...

In this work, the dielectric properties of oil palm fibres/rubber composite materials were characterised as regards fibre content (10, 20 and 30% wt. fibres), fibre diameter and length (two types: macrofibres and microfibres) and treatment (three treatments: silane, benzoylation and added silica). Dielectric properties (loss factor, permittivity, d...

A study of impact hysteresis curves on e-glass reinforced polypropylene laminates was conducted. The strengthening effect of adding Twintex skins on a glass mat thermoplastics (GMT) core was shown at the lower energies, 15 and 20 J. The two Twintex laminates namely 1:1 Twintex and 4:1 Twintex laminates proved complementary as for resistance to impa...

Two alternative geometries were considered for the manufacture of a 6-mm thick component by band lay-up stacking of an E-glass-epoxy twill-weave laminate, with 50(±1) wt% glass fiber content. In the first case, two 3-plies laminates were bonded together using modified epoxy adhesive, using sand paper for surface preparation and compressing the adhe...

Compression tests were carried out on five different implant geometries, obtained varying both the dimension of the thread and the total threaded length of the section in biocompatible Ti grade 3.7035. Results show that both the correctly and the incorrectly applied implants largely exceed the maximum clenching force. However, in the case of off-ax...

Tests were conducted to measure the degradation of the mechanical performances of jute/polyester woven laminates with increasing impact energy. Tensile failure occurred by macroscopic matrix cracking under the point of impact. The results highlight the characteristic patterns of impact damage and post-impact fatigue damage in jute reinforced lamina...

The feasibility of using the thermoelastic stress analysis technique to measure damage severity in woven composite materials is investigated. Controlled levels of impact damage are introduced into strip specimens manufactured from laminated woven E-glass polyester material. Thermoelastic data is obtained for the material in the damaged and undamage...

The feasibility of using the thermoelastic stress analysis technique to measure damage severity in woven composite materials is investigated. Controlled levels of impact damage are introduced into strip specimens manufactured from laminated woven E-glass polyester material. Thermoelastic data is obtained for the material in the damaged and undamage...

Sending ultrasonic signals across the joint area and listening then to received acoustic emission signals constitutes the so-called acousto-ultrasonic technique, widely applied to quality discrimination in joint structures. Here three different types of E glass-epoxy adhesive joints, produced by a handmade procedure, are in a certain measure discer...

Recently published research works showed that the mechanical properties of particulate reinforced metal matrix composites (MMC`s) are strongly affected by damage. It is accepted that such development of microstructural deterioration is related to reinforcement integrity (i.e. particulate cracking or matrix/reinforcement interface debonding) and tha...

One of most promising possibilities to increase toughness of advanced ceramics consists in stabilizing a phase within the material by addition of suitable amounts of a second constituent. This is what happens in zirconia in which we obtain a more relevant toughness due to cubic phase stabilization by adding yttria. In our tests we deal with a PSZ (...

Damage in a 6061-Al/Al2O3P composite was studied by the acoustic emission technique. Tension and compression tests were performed on the composite after either T4 or T6 aging treatments. The comparative analyses of the acoustic emission evolution and the microstructural observations of the materials tested allowed to investigate the effects of matr...

This work is aimed at presenting a simple and innovative method for the measurement of surface void content on both faces of balsa wood samples, slightly heated using an incandescence lamp. Transient IR thermography observation was carried out for one-minute periods during the cooling down of the specimens. The observation was carried out using a F...