[To be continued…]

The overall mechanical behavior shows elastic-brittle features until reaching an ultimate strength and, therefore, a sudden collapse without further deformative contributions.
Schermata 2015-05-25 alle 11.58.01

Figure 1 – A comparative stress-strain graph (www.saimex.it)

Features and advantages:

  1. lightness;
  2. high mechanical resistance;
  3. thermal insulation/thermal break;
  4. fire-resistant;
  5. recommended maximum operating temperature 60°÷90° (using high-performance resins);
  6. maximum temperature range – 40°C ÷ 180°C;
  7. corrosion resistance;
  8. maintenance-free;
  9. radiolucent;
  10. profiles based on customer’s drawings.

If the temperature range is low, the pultruded material doesn’t show any decay of mechanical performance; on the contrary it is possible observe an increase in the strength parameters.
The material leaves a wide margin of designing in relation to its thermal and electrical properties; the longitudinal extension in the direction of fibers is limited, whereas the same doesn’t happen along the two transverse directions. The material takes on a similar behaviour, even when the thermal conductivity is concerned with small changes depending on the fiber used. The response to electromagnetic stresses is on the whole good, although it is rather moderate against the carbon fiber composite materials.
Hereunder you find a comparative table of the key features of Pultruded Materials and of the major competitive materials:

Properties Pultruded Material Steel Aluminium PVC
Density [g/cm3] 1.8 7.8 2.8 1.4
Tensile strength [MPa] 350 – 400 370 – 500 200 – 400 40 – 60
Pull elongation [%] 1.5 – 2.0 13 – 35 5 – 35 10 – 80
Flexural strength [MPa] 400 – 450 330 – 500 200 – 400 70 – 100
Elastic modulus [103 MPa] 25 – 30 210 70 2.8 – 3.3
Flexural modulus

[103 MPa]15 – 20210702.8 – 3.3Impact resistance [MPa/m2]20040020085 – 95Thermal conductivity [W/m°C]0.25 – 0.35100 – 230100 – 2300.15 – 0.25Coefficient of thermal expansion [106 MPa/m°C]5 – 2010 – 1420 – 2550-100Dielectric capacity [KV/mm]5 – 15–40 – 50Volume resistivity [wcm]1010 – 10140.2 – 0.80.028> 1016

Table 1 – comparative table of mechanical features of materials under consideration (www.saimex.it)

[Coming up ‘Tests performed at the Technical University of Milan’]

Share
Read More


Fibers usually  used for structural elements in FRP profiles are made of long continuous fiber glass. It is noted that fibers having a tensile strength show the same elasto-brittle behavior, without any impact on work hardening and softening sections. On the contrary, if they are compressed, the response is inadequate against the previous one. It exhibits a homogeneous and symmetric behavior (isotropic) compared to steel.

Share
Read More


[to be continued ‘production methods’]

 

SMC (Sheet Molding Compound)

a molding composition, is much more similar to automated and continuous processes. It is characterized by medium-high production rates, a stable section and precise and codified tolerances. It originates from a resin impregnated mat (prepregs) formed of short free-fall fibers. The composite is placed inside an aluminium mold under forming press. In this way it undergoes a process of polymerization (‘curing’) that changes the physicality of the material. Therefore a controlled and repetitive process is generated, by which it is always possible to obtain the same result. Then the mold is closed and sealed under pressure and air is drawn in during the curing. It is destined for the production of medium sized elements.

 

BMC (Bulk Molding Compound)

is similar to the previous process, in which the composite is used in the form of ‘prepreg paste mass’; it can be processed using processing methods, such as, moulding, transfer or direct injection inside the mold. This technique is also destined for the production of small-medium sized elements.

 

Pultrusion

a system for the continuous pull extrusion of profiles with a stable section and straight axis, with subsequent curing in the heated closed die. The use of long fibers provides resistance to the product and mechanical responses similar to those which are typical for steel, except for the isotropy of material (the Pultruded Profile is highly orthotropic). Therefore the production is steady and automated; the dies used are made of hardened steel and ensure high production rates, thanks to their very high resistance. At the end of the process the product is cut to the desired length. Examples: IPE profiles, squared profiles, round profiles and profiles with complex shapes.

[Coming up ‘Behaviour of the GFRP composite material’]

Share
Read More





In the light of enhancing its corporate social responsibility, every year Saimex chooses to fund a project, to find an association or a charity, to whom its economic contribution can be devoted.

A strong and key voluntary commitment aimed at defining the role of Saimex within its territorial community, where it operates and develops its activities; a task for dealing not only with the economic aspect, but also with promotion and social support.

Share
Read More


Ad oggi, l’impiego degli FRP (Fiber Reinforced Polymers) per il rinforzo strutturale e post-sismico del patrimonio edilizio è ampiamente diffuso sia a livello nazionale che internazionale.

Al contrario, la considerazione delle fibre nei profili strutturali non è ancora penetrata a fondo nel campo della progettazione, anche se appare fortemente promettente. Le possibili applicazioni sono molteplici e spaziano in ogni campo dell’ingegneria:

 costruzioni edilizie;
 trasporti (copertura per treni, autobus, tram, sponde per camion ecc.);
 aeronautica;
 industria chimica (ambienti corrosivi);
 isolanti per alto voltaggio, trasformatori, ecc.;
 equipaggiamento sportivo (bastoni da hockey, frecce, prue, tende).

I materiali compositi rappresentano quindi una delle ultime innovazioni tecnologiche nel campo dell’industrializzazione del prodotto, con riscontri anche in ambito meccanico, elettrico, elettrotecnico ed altro ancora. La particolarità di questi prodotti risiede nell’unione non solo materica ma anche “caratteriale” di due componenti apparentemente molto diversi tra loro, ma in grado di solidarizzarsi nella risposta meccanica alle sollecitazioni esterne. Sono quindi caratterizzati da leggerezza, resistenza, elasticità e durabilità, ed in tal senso le attuali applicazioni principali sono rappresentate da ponti pedonali e carrabili, strutture leggere permanenti e removibili, ma anche elementi strutturali di dimensioni più o meno contenute.

In particolare, in questa sede si parlerà di Pultruso, un composito generato dall’omonimo procedimento di produzione, che vede collaboranti resine e fibre di diverso genere. Esistono diverse tipologie di Pultruso, differenziate per resina o fibra utilizzata: il processo di produzione è infatti in grado di trattare matrici termoindurenti (resina epossidica, poliestere, vinilestere, acrilico, ecc.) o termoplastiche, in unione con fibre di diverso genere quali fibre di vetro, carbonio o kevlar (aramidica); ma la combinazione più utilizzata al momento risulta essere quella relativa ad isopoliestere e fibra di vetro.

Le normative che attualmente regolano ed indirizzano l’attività dei progettisti nel campo della progettazione strutturale con profili pultrusi rinforzati fibravetro sono le seguenti:

 UNI EN 13706, “Compositi plastici rinforzati – Specifiche per profili pultrusi – Metodi di prova e requisiti generali”;
 CNR-DT 205/2007, “Istruzioni per la Progettazione, l’Esecuzione ed il Controllo”.

 

La settimana prossima parleremo, sempre in ambito di Materiali Compositi FRP delle Tecniche di produzione.

Share
Read More


Ogni anno Saimex, in un’ottica attenta di responsabilità sociale d’impresa, sceglie un progetto da finanziare, un’associazione o Ente benefico al quale destinare il proprio contributo economico.

Un impegno volontario fortemente voluto e centrale per definire il ruolo di Saimex nella comunità territoriale nella quale lavora e si sviluppa; una funzione che non vuole essere solo economica ma anche di promozione e supporto sociale.

Share
Read More