Given:Initial tension of bolt=1200 lbStiffness of clamped joint= 7.6 times the bolt stiffnessExternal force acting on joint = 0 to 7600lbTo draw a graph of bolt force and joint force vs time for 3 or 4 fluctuations of the external load.For a bolt which is preloaded, the bolt force Fb is given by:Fb = Ks x δbwhere Ks is the bolt stiffness and δb is the displacement of the bolt.The stiffness of the clamped joint is given as:Kj = 7.6 KsThe force in the joint is given as:Fj = Kj x δjwhere Kj is the joint stiffness and δj is the joint displacement.δj = δb / (1 + α)Where α is the ratio of the joint stiffness to the bolt stiffness.α = Kj / Ks = 7.6From the above equations, we can say that the bolt force Fb and the joint force Fj are related as:Fb = (Ks / Kj) x Fj = (1 / 7.6) Fj = 0.131 FjThe external load on the joint varies from 0 to 7600lb. Let's plot the graphs for Fb and Fj vs time for 3 or 4 fluctuations of external load.For the maximum external load of 7600 lb,Fj = 7600 lbFb = 0.131 Fj = 994.6 lbAt minimum external load, Fj = 0lbFb = 0.131 Fj = 0lbLet's assume that the external load changes linearly with time. Then the variation of external load with time is given by:Fext = mtwhere m is the rate of change of external load.For 3 or 4 fluctuations, we can assume the external load varies from 0 to 7600lb and back to 0 in 2 seconds. So we have m = 7600 / 2 = 3800 lb/sec.On substituting the values of Fj and Fb in the above equations, we get:Fj = 3800t lbFb = 0.131 Fj = 497.8t lbThe graph of Fj and Fb vs time is as shown below:Graph of Fj vs time:Graph of Fb vs time: