How do $$I calculat the internal forces $($N$)?$

the truss is $$measured by:

$1.$Place the calibrated magnetic link into the truss under test.

$2.$Attach a suitable yoke to $$the joint under test

$3.$Weave the cable through the pulleys, ensuring that the load direction is $$correct

$4.$Hook the weight holder $(50$grams$)$to $$the cable loop and carefully apply masses until the magnetic link fails

$5.$Repeat step $(4)$five times to $$calculate the average