FEA for Transient Responses of an S-Shaped Force Transducer with a Viscoelastic Absorber Using a Nonlinear Complex Spring

To compute dynamic characteristics of nonlinear viscoelastic springs with elastic structures having huge degree-of-freedom, Yamaguchi proposed a new fast numerical method using finite element method [1]-[2]. In this method, restoring forces of the springs are expressed using power series of their elongation. In the expression, nonlinear hysteresis damping is introduced. In this expression, nonlinear complex spring constants are introduced. Finite element for the nonlinear spring having complex coefficients is expressed and is connected to the elastic structures modeled by linear solid finite element. Further, to save computational time, the discrete equations in physical coordinate are transformed into the nonlinear ordinary coupled equations using normal coordinate corresponding to linear natural modes. In this report, the proposed method is applied to simulation for impact responses of a viscoelastic shock absorber with an elastic structure (an S-shaped structure) by colliding with a concentrated mass. The concentrated mass has initial velocities and collides with the shock absorber. Accelerations of the elastic structure and the concentrated mass are measured using Levitation Mass Method proposed by Fujii [3]. The calculated accelerations from the proposed FEM, corresponds to the experimental ones. Moreover, using this method, we also investigate dynamic errors of the S-shaped force transducer due to elastic mode in the S-shaped structure.





References:
[1] T. Yamaguchi, Y. Fujii, T. Fukushima, T. Kanai, K. Nagai and S.
Maruyama, "Dynamic responses for viscoelastic shock absorbers to
protect a finger under impact force," Applied Mechanics and Materials,
vol.36, pp.287-292, Oct. 2010.
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structures with non-linear concentrated spring having hysteresis,"
Mechanical Systems and Signal Processing, vol.20, pp.1905-1922, Nov.
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[3] Y. Fujii, "Measurement of the electrical and mechanical responses of a
force transducer against impact forces," Review of Scientific Instruments,
vol.77, pp. 1-5, Aug. 2006.
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[5] Y. Fujii and T.Yamaguchi, "Proposal for material viscoelasticity
evaluation method under impact load," Journal of Material Science,
vol.40, no.18, pp.4785-4790, 2005.
[6] T. Yamaguchi and Y. Fujii, "Dynamic analysis by FEM for a
measurement system to observe viscoelasticity using levitation mass
method," International Journal of Advanced Manufacturing and
Technology, vol.46, no.9-12, pp.885-891, 2010.