On micro dynamics sensitivity of precision large space structures made of high-modulus fiber polymer composite materials

Causes of problem with micro dynamics sensitivity (MDS) in precision large space structures (LSS) made of high-modulus fiber polymer composite materials (FPCM) were considered associated with a stepwise increase in the material elasticity modulus when overcoming threshold values of the low stresses values. Experimental data was presented on compression tests of tubular reference specimens having the cross-section area of 4.52×10-4 m2 and made of KMU-4L carbon fiber reinforced plastic, where the stepwise module increase after passing the threshold values of low voltages was determined. In this case, average values of the elasticity moduli in the first section (from 0 to 5 kN) and in the subsequent loading sections constituted 7.375 GPa and 158 GPa, respectively. It was demonstrated that during ground testing of precision LSS and due to an error in the applied weightlessness systems (WS), residual loads on their elements exceeded values of the indicated small loads. As a result, under exposure to small loads arising under conditions of an orbital flight calculated values of the elasticity moduli of precision LSS made of high-modulus FPCM could be higher than real values by more than 20 times; and, accordingly, real elasticity deformations of structures could be significantly higher than the calculated ones and could exceed the permissible values. Thus, when using the high-modulus FPCM in precision LSS, for example, in high precision parabolic mirrors (PM) made of carbon fiber reinforces plastic having the diameter of 10 meters or more and the working surface precision of not less than 10 µm, it is necessary to take into consideration their MDS to external and internal micro dynamics effects (EIMDE) in flight conditions. Possible approaches to solving the problem are demonstrated.