I made three trusses from plastic to test and help me develop my ideas for my experiment. The three trusses were 1m by 10 cm, one with two triangular sections, one with four and one with eight. Using the warren truss, these are the only three fesable configurations to experiment with since the number of triangular segments increases in exponents of two since there must be a joint on the lower horizontal member at the mid point.
I made a rig on which we can fix the ends of the trusses in order to test them (see picture below). To test the trusses i suspenses slotted masses from the central joint and measured the diflection. I expected all the force to convert into 2d stress in the individual members of the truss, but instead the truss started to buckle outwards (see pictures below). This is because normally 2d trusses are part of a lattice and take strength from the other lattice members in different planes. In order for my calculations to be valid, all the forces must be within the 2d plane. To keep my trials coherent to the theory behind the tests i will have to ensure that only vertical motion is possible during the experimantation. this may involve making a 3d bridge or beam like shape or fixing the joints on vertical runners. The complications arrise when manipulating variables as it soon becomes difficult to see what i am manipulating or not.
The rig:
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