4-Punkts bøyemaskin

Abstract

Utvikling og beregning av en 4 punkts bøyemaskin for testing av stivhet i bjelker. Maskinen er utviklet for NTNU Gjøvik med hensikt å bygge maskinen og bruke den i testing av både internt lagde bjelker og elementer, men også for eksterne bedrifter i Gjøvik området. Hoved-konstruksjonen til maskinen består av 4 stålsøyler og 2 stykk tykke stålplater som den hydrauliske sylinderen og traversen festes og beveger seg på. Dette gir en rimelig og solid konstruksjon med gode muligheter for modifiseringer og forbedringer over tid etter behov. Sånn som maskinen er bygget og konstruert gir dette en maskin som tåler det den skal og mer til over lange tidsperioder. Maskinen ender også opp med å være rimelig sammenlignet med lignende maskiner i samme størrelsesklasse, siden den med de antagelsene gjort her ikke kommer å koste mye mer enn 1,3 millioner kroner å bygge.

This is a bachelor thesis written for the university NTNU, campus Gjøvik, more specifically the Material and Construction Research Laboratory. The school is in the middle of building their workshop and laboratory in the Mechanical and Construction Departments, and they need a testing machine for testing the bending strength of beams. For this purpose, they want a 4-point bending machine, as these machines give an area of pure bending stress. The purpose of this thesis is to draw and construct the technical drawing of this machine and dimension the machine to handle the loads. The choice of main structure quickly fell on using steel rods and thick plates as a base, with added hydraulic cylinders and other functionality. Among these are adjustment pipes for moving the top of the machine up and down to change the size of the opening, and a slide for holding the equipment witch applies the load on the beam being tested, and reduces off-axis loads on the hydraulic cylinder. It also measures both the force exerted by the hydraulics and the force the beam receives. Cameras and other measuring equipment will be installed to obtain more testing data, with software solutions for capturing, storing, and processing the data from the test, but this is not part of this task. The machine is more than capable of handling the load of 40 tons that it was designed for, even over many cycles of loading. The machine has also been designed to be simple to expand its capabilities for other types of testing over time, one example being testing for buckling, as this just needs a simple attachment on the base and slide. It is relatively inexpensive compared to other commercial solutions in the same size class, coming out at only about 1.26 million Norwegian kroner versus the 4-5 million for commercial solutions in the same class.