In the last three decades, smart materials have become popular. The piezoelectric materials have shown key characteristics for engineering applications, such as in sensors and actuators for industrial use. Because of their excellent mechanical-to-electrical and vice versa energy conversion properties, piezoelectric materials with high piezoelectric charge and voltage coefficient have been tested in renewable energy applications. The fundamental component of the energy harvester is the piezoelectric material, which, when subjected to mechanical vibrations or applied stress, induces the displaced ions in the material and results in a net electric charge due to the dipole moment of the unit cell. This phenomenon builds an electric potential across the material. In this review article, a detailed study focused on the piezoelectric energy harvesters (PEH’s) is reported. In addition, the fundamental idea about piezoelectric materials, along with their modeling for various applications, are detailed systematically. Then a summary of previous studies based on PEH’s other applications is listed, considering the technical aspects and methodologies. A discussion has been provided as a critical review of current challenges in this field. As a result, this review can provide a guideline for the scholars who want to use PEH’s for their research.

Incremental sheet forming (ISF) is an emerging metal-forming technology in which the tool motion is controlled numerically. The process is economical to form complex parts in small to medium batches and provides a short and inexpensive way of forming products having a relatively simple but interesting shape. In this article, a review of the present state-of-the-art technologies and the potential applications of incremental sheet metal forming are presented in brief. This article seeks to address the approaches and methods that are prevalently applied. Furthermore, the article also seeks to guide researchers for future work, by identifying inadequacies of the current approaches and potential for valuable contributions in the field of incremental forming.

With the breadth of applications and analysis performed over the last few decades, it would not be an exaggeration to call piezoelectric materials “the top of the crop” of smart materials. Piezoelectric materials have emerged as the most researched materials for practical applications among the numerous smart materials. They owe it to a few main reasons, including low cost, high bandwidth of service, availability in a variety of formats, and ease of handling and execution. Several authors have used piezoelectric materials as sensors and actuators to effectively control structural vibrations, noise, and active control, as well as for structural health monitoring, over the last three decades. These studies cover a wide range of engineering disciplines, from vast space systems to aerospace, automotive, civil, and biomedical engineering. Therefore, in this review, a study has been reported on piezoelectric materials and their advantages in engineering fields with fundamental modeling and applications. Next, the new approaches and hypotheses suggested by different scholars are also explored for control/repair methods and the structural health monitoring of engineering structures. Lastly, the challenges and opportunities has been discussed based on the exhaustive literature studies for future work. As a result, this review can serve as a guideline for the researchers who want to use piezoelectric materials for engineering structures.

The features of the incremental sheet forming (ISF) process allow it to meet a wide array of customer preferences. In this paper, the variation of surface roughness (SR) in a negative ISF process was systematically studied. The variation was investigated by means of four different process parameters, namely, the vertical step size, forming tool diameter, spindle speed, and feed rate. By using Taguchi analysis with the help of design of experiment and analysis of variance (ANOVA), the effects of the above four process parameters have been studied to optimize parameter levels to realize minimum SR. The results illuminated which parameters have the greatest effect on SR variation, namely, tool size and vertical step size. The confirmation test also showed that the response tables and graphs from Taguchi analysis and ANOVA constitute effective and efficient methods for determining each design parameter's optimal level to produce the minimum value of the SR.