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Fundamentals of Stress and Vibration                1. Mathematics for Structural mechanics
                 [A Practical guide for aspiring Designers / Analysts]


                                             dθ          dy  2
                Further simplifying, we get:  R  =    1 +          - - - - (1.7)
                                             dx          dx

                                                                       2
                               dy                                     d y         dθ
                                                                               2
                We know that      = tanθ  , differentiating again we get:    = sec θ      - - - - (1.8)
                               dx                                     dx 2        dx
                                                            dy  2
                                                  2
                                      2
                We also know that,  sec θ = 1 + tan θ = 1 +
                                                             dx
                                                               2
                                                              d y          dy  2  dθ
                Therefore, equation    .     could be rewritten as:    =  1 +            - - - - (1.9)
                                                              dx 2         dx    dx




                                                                   1           2
                                                                2 2
                         2
                         d y                 2          1 +   dy      ∗  1 +   dy
                        dx 2             dy                  dx             dx
                   R         2  =   1 +   dx        =   R =       d y
                                                                    2

                     1 +   dy                                        2
                          dx                                      dx

                                                                         3
                                                                   dy  2 2
                                                              1 +   dx
                Simplifying the above expression, we get:    R =              - - - - (1.10)
                                                                   2
                                                                   d y
                                                                  dx 2

                                                                                          1
                Expression    .       is that of radius of curvature  R  and curvature is given by    .
                                                                                          R

                   2
                  d y
                        is positive for a concave curve and negative for a convex curve.
                  dx 2



                 ”‘ ȏ ‹‰ ͳǤͳͳȐǡ ™‡ Šƒ˜‡ǣ ȏ †Ʌ α †•Ȑ
                                                       3
                                                 dy  2 2
                                           1 +   dx
                  Radius of Curvature  R  =                  - - - - (1.11)
                                                 2
                                                 d y
                                               dx 2


                 “—ƒ–‹‘ ȋͳǤ͹Ȍ …ƒ ‘™ „‡ ”‡™”‹––‡ ƒ•ǣ





                              QP No. SSC/Q4401, Version 1.0, NSQF Level 7, Compliant with Aero and Auto Industries,   Page 13
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