The 3D-printing revolution is in full swing due to the expiration of a number of pivotal patents causing a proliferation of inexpensive 3D printers. While the 3D printer manufacturers' demonstration objects usually print well, student-designed objects do not, thus causing delays in student projects. This work describes 3D-printing laboratory experiences with unsuccessful prints (based on over 3000 print hours) in an undergraduate engineering 3D-printing lab using inexpensive 3D printers implementing fused deposition modeling (FDM) technology. Unsuccessful prints caused by 3D printer failures and by 3D-printing process failures are classified based on severity (catastrophic, compete, and partial failure types), analyzed, and corrected. The solutions include reprinting the failed objects using different object orientations, changing the printing material, changing the printing platform surface properties, rework by using tools like 3D pens, soldering irons, acetone treatment, etc. Student evaluations show that students understand and accept 3D-printing technology with its capabilities, potentials, and limitations. When dealing with partial failures and time limits, students prefer to correct small defects in complex objects and to reprint simple objects.
IntroductionThe value of experiential learning through laboratory exercises in engineering education and practice is immense and is well established through the Kolb's experiential learning cycle theory 1-3 where active experimentation occupies a prominent role 4-7 . Physical models and prototypes are integral parts of the engineering design process and are also well documented in engineering texts 8,9 and engineering education literature [10][11][12] . 3D printing is a form of rapid prototyping (additive manufacturing) based on material addition as opposed to material removal processes(subtractive manufacturing) such as computer numerically controlled (CNC) machining. 3D printers were used in some engineering programs to create physical models [13][14][15][16][17][18] . These 3D-printed objects were expensive due to the high costs of 3D printers and the materials used. Recently however, a number of new companies started producing inexpensive 3D printers thus enabling their wide use in engineering education 19 . New editions of textbooks started adding chapters on 3D printing and additive manufacturing 20,21 . Now, neither the costs of 3D printers nor the material costs are limiting factors in creating physical 3D objects. This enables students in engineering and engineering technology programs to print a large number of parts relatively quickly while progressing through their iterative designs.
The ionic polymer–metal composite (IPMC) is a new practical engineering material that, it has a wide range of capabilities in both dry and liquid environments. IPMC is a new candidate for diaphragms in micropump devices, micro and Nano robotic applications. IPMCs are regarded as a capable actuator for transportable applications, however, the unique combination of electrochemical and mechanical properties that they possess, such as back-relaxation, restraint their use in real-life applications. There have a lot of attempts to understand and model the IPMCs properties and build a whole prototype that can be used, with certainty, in different robotic, control, and medical applications, yet, till now, it seems that the dehydration and back-relaxation are still not modeled properly.
The Nernst-Plank-Poisson was chosen to be the base model for the IPMC behavior, we were able to create a new model that truly represent the back-relaxation effects that occur in IPMCs, we’ve called the new model as modified NPP model. The modification used captured data from our experimental work Our modified analytical NPP (Nernst-Plank-Poisson) model was the verified using MATLAB & Simulink, which showed that the model, and the controller design for it was able to first compensate the loss of position of the IPMC due to back-relaxation, and then track the desired position input signals with great accuracy. The model and designed controller can be utilized in verity of robotic applications.
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