The use of pultruded profiles is becoming increasingly widespread both for solutions in the private building sector and constructions in the aeronautical and petroleum sector. In all this it is useful to keep it together the advantages that can derive from choosing the pultruded profiles. They are now being used very extensively as solutions for replacing steel, in order to build shelters.
Whether small-sized shelters are built or much wider shelters have been chosen, such as those that can be seen in railway stations, the context does not change. For sure there is a substantial improvement in pultruded profiles that will be appreciated, as far as the resistance to atmospheric agents is concerned. This is essential to pursue overall efficiency, when designing a shelter which is by its very nature much exposed to the elements.
Among the advantages of pultruded profiles for the construction of shelters there is also lightness that can be appreciated especially if you opt for fiberglass profiles, about five times lighter than steel.
It should not be overlooked the possibility to manage everything, including a minor maintenance which will bring about a cheaper price. Furthermore, it is possible to choose a final colour easily. This is an important advantage for a shelter, a structure that should harmonize with the environment irrespective of its size, when using pultruded fiberglass profiles.
Steel has run its course with regard to many solutions, as well as the construction of shelters that can be set up thanks to pultruded profiles, keeping efficiency at the forefront, which ranges from a easier handling on the construction site to the possibility of managing the structure in the fastest and easiest way, without the need for all maintenance operations that it is instead required by steel.
Pultruded profiles have been started to be used in the building sector for some time now, but also for the construction of infrastructures related to the oil and railway sector. Steel has been replaced by pultruded profiles, because their durability is longer, but also for whatever it may concern the lightness, the aesthetics and ease of management on the construction site. In this regard, it is good to specify something in relation to the cut mode of pultruded profiles.
When working on a construction site and there is the need of manipulating a pultruded profile by cutting or boring it, the reference to be considered are diamond blades. Having said this, a basic specification is necessary to understand how is it possible to handle pultruded profiles in practical terms and exploit all the advantages compared to steel, we can go deeper into the details of other technical specifications, by pointing out that pultruded profiles can’t be neither bent nor curved.
With a sigma under tension corresponding to 240 Mpa, pultruded profiles have been designed for specific calculation programs, always starting with orthotropic data. When speaking about technical features of pultruded profilesand cutting mode it’s important to remember their resistance when using diamond blades. At this regard it is possible to make reference to data corresponding to 3000 Mpa.
The pultruded profile is a brittle material for all intents and purposes,but able to withstand extreme temperatures. In this case it’s possible to have a range included between – 40°C and +180°C. When taking into consideration the thermal insulation, a peculiarity that determines the success of pultruded profiles compared to steel, it is possible to gain a full picture describing the revolution that the pultruded profile has been brought to many sectors with considerable advantages both for the work of designers and for the end user who has to bear the costs and for the environment.
[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.
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’]