XXX-X-XXXX-XXXX-X/XX/$XX.00 ©20XX IEEE Piezoelectric Force Sensor-based Measurement System for Recoil Force Analysis Ibrahim Sami Ilter Mechatronics Engineering Department Istanbul Gedik University İstanbul, Turkey isilter@outlook.com Savaş Dilibal Mechatronics Engineering Department Istanbul Gedik University İstanbul, Turkey savas.dilibal@gedik.edu.tr Harun Zengin Industrial Engineering Department Marmara University İstanbul, Turkey harunzengin@marun.edu.tr Abstract—In this study, a piezoelectric force sensor-based experimental recoil force analysis was performed via examining the formation and effects of recoil forces after overviewing the related experimental studies in the literature. The experimental measurement and the analysis of the recoil forces of the selected shotguns were carried out systematically after selecting the accurate piezoelectric force sensor for the dynamic performance of the recoil mechanism. The experimental setup required for the measurement was built via integrating the selected piezoelectric force sensor, signal conditioner, data acquisation card with a software developed in Visual Basic .NET software language. A developed measuring apparatus was designed to measure the dynamic recoil forces of different shotgun system. The selected piezoelectric force sensor can detect the recoil forces with 36 kHz measurement capacity. All of the data were recorded in real-time. The recorded data were examined, and analyzed comparatively. The collected measurement results are evaluated according to the recoil mechanisms, barrel lengths, weights, and other effective parameters that may affect the recoil forces in the experimental analysis. It was observed that the shotgun that spreads the recoil force over time reduces the peak point and has minimum total recoil energy among the gas cycle, inertia and hybrid shotguns with 71cm barrel length and included 12GA caliber. Keywords—recoil force, experimental analysis, piezoelectric force sensor I. INTRODUCTION Humans have used shotguns as one of the significant defense tools for centuries. These instruments are also used in shooting competitions in Olympic games. The advances in shotgun recoil absorber mechanisms dramatically accelerated with the support of detailed engineering background via nonlinear modeling and experimental analysis [1]. Recoil force is the result of the momentum change with the acceleration of the projectile and the pressurized gases generated via combustion [2]. The exit of the gunpowder gas from the barrel accelerates the movement of the shotgun with applied force. When the recoil force cannot be controlled well it can cause some injuries during the shots with shotguns and other light weapons. Additionally, the recoil force can affect the user's performance. The sequence of shotguns’ recoil force occurred inside of the barrel can be analyzed via measuring the applied force of a shotgun using high-speed sensor systems. The accurate measurement of the recoil force can unveil the dynamic performance of the system. Many studies have been made on the dynamic performance of recoil mechanism considering total recoil time and recoil length [3-4]. Different recoil absorber systems were used to reduce the maximum recoil force transmitted to the recoil segment via compansator system. The spring segments, fluid viscous dampers, muzzle brakes are the most common passive recoil compensator mechanisms. In addition to the passive recoil absorber, the magnetorheological (MR) [5] and electrorheological (ER) [6] smart fluid damper systems have been proposed in the literature as novel effective recoil absorber mechanisms with dynamic yield strength. Recent studies have considered the use of shape memory alloys (SMA) as alternative damping elements [7] for many potential applications in industry with their unique superelastic response and shape memory characteristics. They can work in different smart systems in two-way [8] or antagonistic manner [9-12]. According to the Newton's third law, the felt recoil force by the shooter from the shotgun is equal and opposite to the force the shooter applies on the shotgun. Thus, the magnitude of the recoil force and the magnitude of the applied force by the shooter with the time histories are directly related to many parameters, such as shooting style and shotgun operation mechanism [1]. The sensor selection process is an important phase to detect the applied dynamic peak forces in the experimental studies. The selected sensor should offer high resolution for measuring the recoil force in a real-time experimental system. In terms of the operation mechanism, the shotguns have mainly gas-operated, inertia, and hybrid operating systems. These are the most preferred semi-auto shotgun operating systems by hunters, shooters, and manufacturers. In this study, the measured recoil forces of three different semi-automatic shotguns with different operating systems were compared. Semi-automatic shotguns can be fired via throwing the empty cartridge after each trigger pull, loading a new cartridge into the chamber from the magazine, and pulling the trigger again. Shotguns with different operating systems provide the required energy to dispose of the empty cartridge after firing and to replace it with a new cartridge with different methods. Gas-operated semi-automatic shotguns perform these operations using the pressurized gas in the barrel during firing process. As shown in Fig. 1, the gas-operated semi-automatic shotguns allow them to cycle by transferring some of the gunpowder gas behind the bullet onto the bolt through the gas port.