Sandwich load carrying panel, reinforcement of sandwich load carrying panel, load carrying frame, attachment of sandwich load carrying panels, heat transfer, fire safety.
Cutouts in construction sandwich load carrying panels, or construction panels cause mechanical properties of sandwich load carrying panels to significantly deteriorate. Due to this problems the sandwich load carrying panels must be reinforced on weak points which is usually carried out with sub-frames of various materials or reduction of distances between supports of sandwich load carrying panels.
The present solution is solving technical problem of reinforcement of construction sandwich load carrying panels weakened due to cutouts in panels whereas the invention is technically simple and affordable. Invented reinforcement of sandwich load carrying panels does not cause additional heat loss, does not cause deterioration of fire safety and at the same time it is appropriate fundament for quality building of windows, doors and other elements of construction elements, air ducts ...
The solutions currently available for cutouts of sandwich load carrying panels do not offer solutions by the manufacturers of sandwich load carrying panels to improve mechanical properties deteriorated due to cutouts (e.g. due to windows, doors, ...).
So far the manufacturers of sandwich load carrying panels have been forwarding information to buyers or assembly crews that appropriate sub-frame has to be constructed of steel, aluminum or similar beams of any material capable of load carrying said panel cannot sustain due to cutout..
Construction of sub-frame in so far known solutions requires knowledge of additional horizontal (or vertical) beams for attaching of edge of cutout of sandwich load carrying panel whereas this sub-frame is usually covered with decorative edge. From the inner side this sub-frame can usually be seen and usually bothersome for the buyer.
During past years much research was done on influence of size and form of cutout on loss of load carrying capacity of sandwich load carrying panels. For that purpose several experiments were carried out in various institutions, universities and companies. The computations are usually performed using differential or integral numerical methods (finite element method, finite difference method, finite volume method, boundary element method ...) whereas finite element method can be found most frequently.
The basic criteria for said experiments and computations are in particular:
In the literature several publications can be found for determining various factors and limitations during use of sandwich load carrying panels with cutouts, however, with no shown solutions for increase of load carrying capacity of panels weakened by cutouts. In particular cases were analyzed, deformations determined and failure locations shown for simulation of various loads on different sandwich load carrying panels.
Described invention shows reinforcement of sandwich load carrying panel or construction panel by replacing visible sub-frame with a frame built into the sandwich load carrying panel as defined in claim 1.
This invention relates to system of strengthening or self-carrying sandwich panel on weakened spots. Typical weakening is cutout in said panel for building in of windows, doors, air ventilation needs, or general penetrations. The system shown in this application has significantly increased load carrying capability deteriorated due to cutout of part of sandwich load carrying structure whereas the sandwich panel is comprise of two thin load carrying covering layers and soft shear carrying core. The outer layers may be of different materials, for example of any metal sheet or thin layer of carbon fiber or glass fiber with joining polymer material. The core can be comprised of various materials such as for example polyurethane foam, mineral wool, glass wool, honeycomb or any other preferred insulation filling.
Self carrying sandwich panels may be straight, bent, finned or designed in any other manner which does not limit the scope of this invention. In addition, the essence of this invention is not limited by form of weakening or cutout.
As far as cutout stress is concerned the reinforcement is performed in such a fashion to take over as much as basic load as possible. In this invention presented reinforcement of sandwich load carrying panel takes over at least 80% of basic load. The reinforcement frame should not be too rigid as this would result in inability to bent partially with sandwich load carrying panel. If the frame is appropriately slim (i.e. correctly rigid) this is beneficial as the whole system operates similarly to sandwich load carrying panel which bends during loading and returns in initial position. If the frame would be too rigid this would mean particularly problematic situation for confection between frame and sandwich load carrying panel and for failure of glue due to large local shear stress. On the other side too rigid frame would result in higher investment in material for the frame (costs).
For correct embodiment of solution shown in this application of reinforcement of sandwich load carrying panel is of particular relevance choice of frame of appropriate elasticity so the frame partially takes over the loads and behaves under these loads similarly to sandwich load carrying panel of full cross-section.
With building in the frame there is reduced transfer of load onto the neighboring load carrying panels which favors allowable distances between supports which have been preselected based on experiments for each type of product and system of built (single field, two field, several field). With solution as shown one may use tables of allowable distances and static calculations also for sandwich load carrying panels with cutouts as the system is know and can be officially recognized using standardized tests as statically verified system.
Solution as shown in this invention also satisfies requirements of construction physics:
Typical examples of use of said reinforcement of sandwich load carrying panels are cutouts for insertion of windows or doors whereby on each panel one or several cutouts can be made.
Below the essence of invention is presented in more detail with description of preferred embodiments and attached figures whereby the figures form part of this patent application and show:
As shown in
The embodiment in
For interconnection of reinforcements glued on both sides of sandwich load carrying panel 1 used insulation interfaces are thermal insulating resulting in prevention of establishment of heat bridges.
The subject of this invention relates also on cutouts where particular side of cutout does not border on sandwich load carrying panel (such as for example assembly or insertion of doors) which does not limit the scope of this invention.
For gluing of reinforcement 2 onto sandwich load carrying panel 1 glue 6 is used with shear module larger than 10 MPa and adhesiveness larger than 5 MPa.
Use of invention according to this application results in significant reduction in use of materials and at the same time in improving of aesthetics of sandwich load carrying panels as opposed to currently used sub-frames.
It is self evident that the invention as described herein can be used in different embodiment which does not alter the essence of this invention limited by the subsequent claims.
This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.