Mechanic of Advanced and Smart Materials

Abstract In this research, the impact properties of epoxy biocomposites reinforced with nano cellulose and nano rosemary plant extract from Lorestan are investigated. The samples were made in 4 different weight percentages (pure, .5% by weight, 1% by weight, 1.5% by weight, 2% by weight) for uniform explanation and the quality of the construction was checked by scanning electron microscope. The results of this investigation show that the distribution of all types of nanoparticles is completely uniform up to 1.5% by weight, and after that, lumpiness of the particles is observed. In the next step, the samples are subjected to the Izod impact test, which obtains the most absorbed energy for all types of reinforcements in 1.5% by weight of nanoparticles, and after that, in the 2% by weight sample, this value significantly decreases. It starts to decrease. This trend can be due to the agglomeration of nanoparticles in epoxy, which has caused a decrease in mechanical properties. In the last step, in order to check the accuracy of the obtained results, for all types of samples of uniform distribution, modeling was done using the finite element method and with the help of software, and the modeling results were compared with the laboratory results.

Abstract Drilling is one of the most common surgical methods performed on human bones to stabilize fractured bones and hold them together. Due to the complexity of the machined material and the sensitivity of the process, it is considered one of the most significant mechanical techniques in biomedical engineering. Polymethyl methacrylate (PMMA), due to its mechanical properties similar to bone tissue, is regarded as a suitable alternative for bone in medical implants. However, increased drilling forces can damage bone tissue or implants, leading to severe and irreparable issues. Therefore, studying the factors influencing drilling forces in such materials is of utmost importance.

In this study, the sensitivity analysis and optimization of axial force in the orthopedic drilling process using tools coated with a nanostructured titanium nitride (TiN) coating applied via physical vapor deposition (PVD) have been investigated. The primary objective of this research is to enhance the performance and efficiency of the process by optimizing parameters such as tool rotational speed, feed rate, tool diameter, and the use of the titanium nitride coating. Sensitivity analysis was also conducted by analyzing experimental data. The results indicate that using coated tools can significantly reduce drilling forces.

Abstract This study proposes an innovative method for harvesting energy from vehicles as they pass over speed bumps by leveraging piezoelectric materials. The core aim is to harness mechanical vibrations produced by vehicle motion and convert them into electrical energy, which can then be used to power low-energy urban infrastructure, such as traffic sensors and street lighting. To simulate this process, a cantilever beam model fitted with a piezoelectric patch was utilized, with excitation through non-contact magnetic force. The equations of motion were formulated based on the Euler-Bernoulli beam theory and subsequently solved numerically using MATLAB. Experimental validation was carried out by testing the system at two distinct velocities of the passing mass and three varying distances between the mass and the beam. The results show a good correlation between the mathematical model and the experimental data, confirming the model's reliability. Analyses indicate that increasing the velocity of the passing mass causes a decrease in the output voltage, and increasing the distance of the object from the magnet also leads to a decrease in the magnetic force and a drop in the generated voltage. Moreover, the findings suggest that, when optimized, the system can deliver a promising level of efficiency in generating power.

Abstract In various industries, structures are made by connecting parts with similar or dissimilar materials. Among these, adhesive bonding is one of the methods for permanently joining structures and creating a cohesive assembly.The single-lap adhesive joint is one of the most commonly used joints in various industries, and its different aspects have been examined in previous studies. However, no research has simultaneously investigated the effects of all mechanical properties of the adhesive and its geometry.This study aims to examine the impact of both mechanical and geometric properties of adhesives using Abaqus software and numerical simulations, which have been validated against numerical and experimental results from a reference paper. For the Statistical Analysis, Minitab software and the Taguchi method were employed, examining eight parameters including elastic and shear modulus, tensile and shear strength, mode I and II fracture toughness of the adhesive, adhesive thickness, and the elastic modulus of the substrate. The results showed that with the increase in mode I fracture toughness, increase in mode II fracture toughness, increase in shear strength, increase in tensile strength and increase in the elastic modulus of the substrate, the strength of the joint increases. Among the adhesive properties, the mode I fracture toughness has the highest effect on the joint strength with a contribution percentage of 28.28. Following that, tensile strength has a contribution percentage of 20.28, mode II fracture toughness has 13.24, shear strength has 8.14, and the elastic modulus of the substrate has a contribution percentage of 4.37 in the joint strength.

Abstract The simultaneous enhancement of impact resistance and reduction of structural weight presents a key challenge in engineering applications, particularly in aerospace and automotive industries. This study aims to develop lightweight high-performance structures by optimizing the internal cellular geometry of 3D-printed components. Polylactic acid (PLA) specimens were fabricated using fused filament fabrication with three cellular patterns (circular, decagonal, and hexagonal), and two orientation schemes (linear and diagonal). The impact behavior of each configuration was evaluated through both experimental Charpy impact tests and finite element simulations. A systematic analysis was performed to assess the influence of cell geometry and orientation on energy absorption, weight reduction, and fracture characteristics. The results revealed that hexagonal cell configurations yielded the highest energy absorption, with up to a 62% increase in impact strength despite a 36% reduction in mass compared to baseline designs. Diagonally oriented cells significantly prolonged fracture duration, showing a 575% increase in time to failure, attributed to the formation of additional plastic hinges and inclined crack paths. These findings demonstrate that strategic internal cell design can substantially improve mechanical performance without additional material usage.

Abstract In this investigation, the influences of cancer illness and related treatments on the mechanical specifications of rat healthy and cancerous (C6) brain cell were studied using nanoindentation by AFM. Chemotherapy as the first treatment was done by Cisplatin anti-cancer drug. The ideal concentration of Cisplatin was found by MTT assessment and supposing IC50 cell viability concentration for 24- and 48-h cultures. The results showed that Young’s modulus of healthy cell was decreased due to cancer and reached from 17.79 kPa to 2.446 kPa (0.139 times). By chemo treatment the Young’s modulus increases from 2.446 kPa to 3.482 kPa (1.423 times) and 38.38 kPa (15.691 times) for 24 and 48-h culture times. The second treatment was plasma treatment and was done for 30 and 60 s for 24 and 48-h culture times. The outcomes showed that applying the plasma treatment raises rapidly the cell rigidity for 48-h culture time. The results displayed that the width of rat healthy brain cell was larger than C6 (1.744 times). In the next section, theoretical and experimental methods were used to obtain the resonant frequencies and amplitude of the frequency response function of the AFM beam’s motion by supposing cells as specimens. The outcomes displayed that rising the specimens’ rigidity increases the resonant frequency. As the result, the resonant frequency of treated cells is bigger than untreated cell. Finally, the FEM and experimental results were evaluated. The comparison displays good agreement.

Abstract Nowadays, the separation of carbon dioxide (CO2) from other gases such as nitrogen (N2) and methane (CH4) is considered one of the main environmental challenges and has received much attention. Compared to different gas separation technologies, membrane technology has attracted much attention due to its many advantages such as modularity and low cost over other technologies. The correct selection and design of membrane materials is the most important and effective factor in its final performance. Nowadays, the use of nanoparticles with different morphologies has been investigated to prepare high performance mixed matrix membranes (MMMs). In this research, a new mixed matrix membrane (MMM) based on polyimide (PI) and metal-organic frameworks (MOF) with specific morphology was prepared. MMMs were prepared using solution casting-solvent evaporation method and their performance in CO2/CH4 and CO2/N2 separation was investigated. The results showed that the presence of particles with ellipsoidal morphology increased the rate of CO2 diffusion and as a result increased membrane performance. The membrane containing 8 wt.% of filler showed the best performance in CO2 permeability and CO2/CH4 and CO2/N2 selectivities at 2 bar and 25°C, which were about 1079.12 barrer, 56.96 and 53.88, respectively. The performance of synthesized membranes in CO2/CH4 separation exceeds Robeson's upper limit and is placed on it for CO2/N2, which can be recognized as a suitable option for industrial CO2 gas separation.

Abstract This research explores the potential of biomimetic geometries derived from natural leaf shapes to study flow-induced vibrations (FIV) and energy harvesting through experiments in a wind tunnel. Five real tree leaves (grape, fig, silver maple, hawthorn, and Norway maple) were selected, their 2D profiles extracted, and converted into physical test models. Each model was mounted on a flexible beam inside a wind tunnel and equipped with piezoelectric strips to measure electrical signals generated from oscillations. Simultaneously, a high-speed camera tracked the transverse displacement of each model throughout the test. Among all cases, the fig leaf geometry exhibited the highest vibration amplitude and frequency stability, resulting in the maximum harvested power. The grape leaf followed in performance, combining strong vibration responses with reasonable energy output. Although the silver maple showed limited response at lower wind speeds, it performed efficiently at higher speeds. In contrast, the hawthorn and Norway maple models produced smaller vibrations and lower frequencies, resulting in lower harvested power. These findings clearly demonstrate the crucial role of geometry in optimizing vibration-based energy harvesting performance.