Page 376 - Mechanics Analysis Composite Materials
P. 376

Chapter 7.  Environmental, special loading, land  manufacruring effects   361



                               120

                                ao


                                40

                                 0                            0"


                                40

                                -80

            Fig. 7.52.  Dependence of residual strains in a glass-epoxy filament wound cylinder on the winding angle
                                    -calculation, o experiment.


            data  of  Morozov  and  Popkova  (1987). As  can  be  seen, the  composite cylinder
            experiences in the general case not only the change in its length (E,)  and diameter
            (E,.),  but also twist (r,,).
              To  study  the  h$angle-ply  layer,  we  should  attract  the  thermoelasticity
            constitutive  equations,  Eqs. (7.23).  Neglecting  bending  and  coupling  stiffness
            coefficients we can write for the case under study



                                                                              (7.83)


            Applying  these equations to  the  angle-ply composite cylinder removed from the
            mandrel we should put N, = 0, N,, = 0 because the cylinder is free of loads and take
            E:  = El,  E$  = E2  in  Eqs. (7.18), (7.25) and (7.26) that  specify NIT and N~T.Then,
            Eqs. (7.83) yield the following expressions for strains that appear in the angle-ply
            cylinder after it is removed from the mandrel:
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