The bicycle helmet has a significant role in reducing and preventing impact because of reducing the deceleration of the skull, spreading the area over which the forces of the impact reach them and preventing direct contact between the skull and the impacting object. Honeycomb structure, due to its elastic properties, extends the energy absorption time of the whole structure and also increases the ability of the whole structure to absorb energy. Therefore, it can be used in the liner designing of a helmet to reduce velocity, energy, and acceleration in impacts. In this paper, intending to identify the minimum stress transmitted to the helmet during an impact, we used Rhino software to model a helmet with honeycomb liner and outer shell and then analyzed it in Abaqus software. Due to the fact that the size of various parts of the head is different in people, so for more comfort and safety, the use of customized-helmet is emphasized. To design and make a customized-helmet, the materials used in designing the helmet are ABS and PETg filaments, which can be used in 3D printing. These two materials have been analyzed with four compositions for the liner and the shell of the helmet. The results show that the best combination of the helmet with Minimum stress transmission and appropriate plastic strain due to impact is the helmet case with honeycomb liner of PETg and a shell made of ABS. پرونده مقاله

Nowadays, disposable injection pumps are widely used in hospitals and home care settings to provide various therapies such as chemotherapy, antimicrobial, analgesic, and anesthetic treatments, as well as for postoperative pain control and chronic pain control. Since the accuracy of the injection is very important in infusion pumps based on the flow rate, it is therefore important to reduce the error in this device. In this study, the basic design principles of these pumps and the design problems of the sample appearance available in the market were investigated. Since one of the vital problems of this type of pump is their inaccuracy, because they are unable to inject a certain amount of drug for a certain period of time, so one of the main objectives of this study is to improve the accuracy of the injection. Also, as this device is available to the patient for a long time at the time of injection, ease of use is one of the design goals. Finally, this paper ends with a design and prototype which is better in the shape of the device and a big improvement in the accuracy. پرونده مقاله