Development and validation of an automated FEM-based design optimization tool for continuum compliant structures

Suat Coemert,Vincent Bott,Yilun Sun,Baturay Yalvac,Tim C Lueth

doi:10.1007/s10999-020-09506-w

Abstract

This paper presents a design optimization method for continuum compliant structures. The developed optimization tool enables automated design, analysis and optimization of the compliant structures in a single simulation environment. The associated algorithm used automatically analyses the stress distribution occurring under certain loading and deformation conditions of initial designs defined by the user, adjusts a uniform stress distribution among individual flexure hinges by automated dimensioning and finalizes the design by integrating mechanical stops automatically matched with the kinematic capacity of individual hinges. In order to prove the advantages of the proposed optimization method, validation tests were performed under static and dynamic loading conditions. Results of the experiments showed that, compared to the non-optimized ones, optimized structures with the developed tool exhibit more uniform curvatures which indicate more even stress distribution among the individual hinges; up to 25% value increase in terms of maximum bearable load and maximum permissible deflection angle; less plastic deformation in case of overloading and up to 100% increased fatigue life.

Highlights

1.1 BackgroundMinimally invasive surgery (MIS) has established itself in many surgical applications as a standard procedure due to its minimal access methods through small incisions or natural orifices (Oh et al 2014)
It can be noticed that simulation and experimental results are in good agreement, as the deviation in the deflection angles of individual hinges is in the range of ± 0.5° for about 85% of the cases
In order to maximize the benefits of minimally invasive surgery and extend its application to wider spectrums, there is a need for small and strong flexible surgical instruments, since rigid instruments sometimes are too limited in terms of reachability in complicated anatomies

Summary

Introduction

1.1 BackgroundMinimally invasive surgery (MIS) has established itself in many surgical applications as a standard procedure due to its minimal access methods through small incisions or natural orifices (Oh et al 2014). There is still a substantial need for small and flexible instruments for particular applications where rigid instruments reach their limit in terms of optimal accessibility due to anatomical constraints (Schneider et al 2013) One example of such an application is the endoscopic frontal sinus surgery, where the rigid instruments cannot reach the pathologies more lateral than lamina papyracea (Conger et al 2014). Another example is the transurethral bladder surgery, where rigid instruments cannot provide retroflexion to reach the tumors around the bladder neck (Herrell et al 2014) In such situations either open surgery becomes the preferred choice or the acceptance of the pathology is chosen over the risk presented by surgery. The development of novel small and flexible instruments is of crucial importance

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Discussion

Conclusion