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Quasi-Static Response of Serial Flexible-Hinge Mechanisms
Published in Nicolae Lobontiu, Compliant Mechanisms, 2020
In order to transfer motion, compliant mechanisms rely on connecting rigid links (that confer rigidity and stability to the mechanism) to flexible links (hinges) that, through their elastic deformation, enable the adjacent rigid links to undergo relative displacements. Such connections of multiple rigid links with flexible hinges result oftentimes in serial chains, like the lever sketched in Figure 5.7a, which is subjected to in-plane external forcing (actuation and payload) and undergoes in-plane displacements.
A Smart Microfactory Design: An Integrated Approach
Published in Wasim Ahmed Khan, Ghulam Abbas, Khalid Rahman, Ghulam Hussain, Cedric Aimal Edwin, Functional Reverse Engineering of Machine Tools, 2019
Syed Osama bin Islam, Liaquat Ali Khan, Azfar Khalid, Waqas Akbar Lughmani
A five-axis micromilling machine based on PC control system is presented in [29], the machine is designed from microstages in market, control board that can be installed in PC, and available air spindle. Stepping motors drive each stage; therefore stages have high-speed resolution. Another five-axis micromilling machine based on PC control system is proposed in [30]; the machine tool is supported throughout with aerostatic bearings, and in addition these bearings are further assisted by squeeze oil-film. Diamond tool is proposed for cutting the job. There are shortcomings of these conventional technologies: high cost effect, low natural frequencies, friction, low control, and low accuracy, which can be overcome through use of flexure-based compliant mechanisms. Different advantages can be accrued by using these mechanisms like cost effectiveness, frictionless joints, removal of backlash as in case of gears, and compatibility to vacuum. A compliant mechanism can be described as a uniform shape structure whose working depends on its flexible material’s deflection. It should be ensured that the compliant mechanism should work in elastic domain without inducing any plastic deformation by manipulating its structural parameters [31]. A 3-DOF compliant micropositioning stage was presented in [32], which is developed using notch flexures. Three piezoelectric (PZT) actuators are used for actuation and are placed at 120° apart in a symmetrical manner because of which large yaw motion can be achieved. A 2-DOF translational parallel micropositioning stage was presented in [33]. The degrees of freedom for each stage are achieved by serially connecting different types of compound flexures. PZT actuation is used for micropositioning/nanopositioning. The results showed good tracking and positioning performance. A simple idea of flexures to be used as control devices for linear stages was presented in [34] for the MEMS accelerometer design. A unique design where the flexures are used for controlling the rotation of rotary stage was presented in [35].
Design for energy absorption using snap-through bistable metamaterials
Published in Mechanics Based Design of Structures and Machines, 2023
Andrew Montalbano, Georges M. Fadel, Gang Li
The structure investigated in this paper is a compliant mechanism that features two unique properties: bistability and snap-through. Bistability is when a system stores and releases energy to have two distinct stable states (Camescasse, Fernandes, and Pouget 2014). Snap-through is a geometric condition (Qiu, Lang, and Slocum 2004) that refers to when a system rapidly transitions between its stable states. A compliant mechanism exhibits advantages over partially compliant and mechanisms: it eliminates friction, increases efficiency, and eases manufacturing (Gou and Chen 2018). One such structure with both of these properties is a curved beam (Qiu, Lang, and Slocum 2004; Hussein et al. 2015). A previous study has shown that a periodic metamaterial consisting of bistable curved beams made from an elastic material produces a structure that exhibits hysteretic energy loss (Debeau, Seepersad, and Haberman 2018).
3.5 mm compliant robotic surgical forceps with 4 DOF : design and performance evaluation
Published in Advanced Robotics, 2023
D. S. V. Bandara, Ryu Nakadate, Murilo M. Marinho, Kanako Harada, Mamoru Mitsuishi, Jumpei Arata
One of the important design considerations in compliant mechanisms is to avoid the breakage and fatigue failure during cyclic motion. This can be achieved by maintaining the deformation within the maximum yield strain of the material. Furthermore, the geometry of the design and thickness of the material affect the stress distribution and deformation. In a similar manner, the thickness of the material and geometry of the structure also affect the range of motion and output of the final design. Therefore, the dimensions of the elastic structure need to be selected by compromising all three factors: range of motion, output, and stress distribution. Moreover, despite the thin structure, due to the larger bending radii by default, the compliant mechanisms also have some limitation in designing structures for further miniaturized surgical robots. In addition, surgical instruments generally need to be bio-compatible, sterilizable, and robust against electrical noise. To this end, this sudy introduces robotic forceps that enable the strain concentration to remain locally in the flexible structure [27], while realizing the bending motion with a shorter radius.
Design of compliant constant-output-force mechanisms using topology optimization
Published in Engineering Optimization, 2022
Qi Chen, Qi Wen, Xianmin Zhang, Yong Yang, Guangming Xie
Compliant mechanisms are flexible mechanisms that achieve force, motion or energy transmission partly through elastic deformation. Compliant constant-force mechanisms (CCFMs) are compliant mechanisms that provide nearly constant forces over a prescribed deflection range. Because of this mechanical property, CCFMs are useful in various fields. CCFMs can be used to perform constant-force operations on arbitrary objects, such as microinjection (Wang and Xu 2017), microgripping (Ye et al. 2021) and non-destructive picking of vulnerable fruits (Miao and Zheng 2020). CCFMs can also be used to limit the maximum contact force and maintain contact between two surfaces, such as in cardiac ablation catheter equipment (van de Sande et al. 2021) and fitness equipment (Sanchez-Salinas et al. 2019). Moreover, CCFMs can be applied in conjunction with ultralow frequency vibrations, such as in energy harvesting and wave attenuation (Zhou et al. 2021).