Vol.:(0123456789) 1 3 https://doi.org/10.1007/s00170-022-09875-w ORIGINAL ARTICLE An experimental investigation on performance of NiTi‑based shape memory alloy 4D printed actuators for bending application Rakshith B. Sreesha 1  · Saiyadali H. Ladakhan 1  · Deepak Mudakavi 1  · Somashekara M Adinarayanappa 1 Received: 17 July 2022 / Accepted: 28 July 2022 © The Author(s), under exclusive licence to Springer-Verlag London Ltd., part of Springer Nature 2022 Abstract The 4D printing technology is gaining immense attention towards developing actuators, soft robots, and sensors, which use Smart Materials (SMs) for their functioning. One of the forefront applications of the 4D printing technique is building actua- tors exhibiting high force of actuation, high stability, and repeatability by using a class of shape changeable SMs termed the Shape Memory Alloys (SMA). The present study is an experimental investigation of the performance of compositionally dif- ferent SMA-based 4D printed actuators built using Ni–Ti, Ni–Ti–Cu, and Ni–Ti–Fe alloys. The evaluation of the performance of the built actuators is carried out through determining the debonding strength of matrix-alloy interface, and the functional capabilities, such as, the force of actuation, residual strain recovery, percentage of displacement reduction. A comparison of both the debonding strength and the functional capabilities for the chosen actuators is carried out, and individual actuators’ parameter-specifc possibilities are reported. Also, the results reaped in the present study act as the baseline data to choose a specifc actuator for a targeted application. Keywords 4D printing · Shape memory alloys · Debonding strength · Force of actuation · Residual strain recovery · Percentage of displacement reduction 1 Introduction 3D printing qualifes as an Additive Manufacturing (AM) technique that involves building static parts in a layer-wise fashion. According to Qunijin et al., the market size of 3D printing considering all the sectors is expected to reach about 36.2 $ Million by 2025 (Compound Annual Growth Rate (CAGR) of about 28.5%) [1]. There is potential to imbibe specifc skills with respect to both the technology and the process in terms of ameliorating the existing soft- ware (slicing) and improving printing consistency of multi- material products (a part of Big Area Additive Manufactur- ing (BAAM)) respectively [2]. An intrinsic limitation of the above technique lies in its inability to develop 3-dimensional (3D) structures involving dynamicity. As a solution, smart materials are employed in conjunction with 3D printed structures in specifc orientations to achieve desired levels of structural transformation when exposed to external stimu- lus. The above integration process fosters a novel technology widely known as 4D printing, where time is considered the 4th dimension. Thus, Fig. 1 illustrates the diference as well as the interrelation of the 3D and 4D printing techniques. Based on the type of the 3D printing technique and the smart material chosen, a specifc type of 4D printed product is developed. This emerging technology is being developed rapidly owing to its wide range of potential applications in the felds of biomedical (Ex. prosthetic limbs), automobile (Ex. Self-actuating air bag system), aerospace (Ex. mor- phing wing), and soft robotics [3–7]. Various 3D printing techniques can be appropriately converted to the correspond- ing 4D printing techniques with inclusion of suitable smart materials. The performance of the established 4D printers can be enhanced by improving the User Interface (Software upgradation, ergonomics enhancement, etc.) [7]. 4D printing is the process used to develop multi-functional dynamic structures that have the ability to change their shape/orientation over time when subjected to external stim- uli, viz., changes in temperature, humidity, stress, electric feld, magnetic feld, etc. [8–12]. Such 4D printed dynamic structures fnd their applications in self-folding containers, * Somashekara M Adinarayanappa somashekara@iitdh.ac.in 1 Department of Mechanical, Materials and Aerospace Engineering, Indian Institute of Technology Dharwad, Dharwad, Karnataka 580011, India / Published online: 2 August 2022 The International Journal of Advanced Manufacturing Technology (2022) 122:4421–4436 Content courtesy of Springer Nature, terms of use apply. Rights reserved.