Mechanical performance analysis and experimental study of soft-bodied bird-billed pneumatic gripper

Purpose Flexible mechanical gripper has better safety and adaptability than a rigid mechanical hand. At present, there are few soft grippers for small objects on a millimeter scale. Therefore, the purpose of this paper is to design a soft pneumatic gripper for grasping millimeter-scale small and fragile objects such as jewelry and electronic components. Design/methodology/approach By simulating the clamping action of the bird’s mouth and combining the high flexibility of the soft material, the bird’s beak soft pneumatic gripper is designed. First, the internal cavity of the gripping end of the gripper is determined by bending deformation calculation, and the brief manufacturing process of the gripper is outlined. Then, the single finger of the soft gripper is modeled mechanically, and the relationship between air pressure and bending deformation of the single finger is obtained. Finally, the experimental platform of the soft mechanical gripper is built, and the gripping performance of silicone rubber material is tested by comparison test, bending deformation test, stability test, adaptability test and gripping accuracy test. Findings The designed gripper has the advantages of simple structure, convenient operation, easy grasping of different small objects of millimeter-scale and good adaptability. It can grasp the precise dispensing needle with a minimum diameter of 0.19 mm, and its accuracy meets daily use. Originality/value A new type of soft pneumatic, the mechanical gripper is proposed and manufactured. According to the shape of the bird’s beak and the calculation of bending performance, a hollow finger gripper with better bending performance is designed. Various test results show that the gripper has a significant clamping effect on millimeter small objects, which supplements the research field of millimeter small object gripper.

Experimental Study on Restoration of Deteriorated Timber due to Termites by Resin Filling

There are many valuable wooden buildings in the world, because timber has been used all over the world as a building material for a long time. However, there is an issue that timber deteriorates due to various factors. Therefore, in order to preserve these valuable wooden buildings, it is necessary to appropriately repair or reinforce treatment. One of the treatments is the resin filling method. In this method, filling the resin in order to restore the strength into an internal cavity caused by deterioration. It has become clear that it is possible to recover the strength using this method, however, we are still conducting construction based on the rule of thumb. Therefore, authors examined the resin characteristics in order to inject the resin in stable manner and ensure strength recovery. Authors focused on deteriorated timber due to termites, because Japan has a very high amount of such type of timber. Authors reports the following four aspects of the characteristics of resin filling into timber. 1. The Area velocity is determined by the injection pressure, width of the gap, and viscosity of the resin. 2. The resin spreads concentrically in the gap of wood, but there is no regularity in the random gap like deteriorated timber due to termites. 3. Authors proposed a new coefficient for the application, of a theoretical formula to deteriorated timber due to termites. 4. Authors proposed a flowchart of resin filling method to perform stable construction.

Control of extrinsic porosities in linked metal-organic polyhedra gels by imparting coordination-driven self-assembly with electrostatic repulsion

The linkage of metal-organic polyhedra (MOPs) for the synthesis of porous soft materials is one of the promising strategies to combine processability with permanent porosity. Compared to the defined internal cavity of MOPs, it is still difficult to control the extrinsic porosities generated between crosslinked MOPs because of their random arrangements in their networks. Herein, we report a method to form linked MOP gels with controllable extrinsic porosities by introducing negative charges on the surface of MOPs that facilitates electrostatic repulsion between them. A hydrophilic rhodium-based cuboctahedral MOP (OHRhMOP) with 24 hydroxyl groups on its outer periphery can be controllably deprotonated to impart the MOP with tunable electrostatic repulsion in solution. This electrostatic repulsion between MOPs stabilizes the kinetically trapped state, in which a MOP is coordinated with various bisimidazole linkers in a monodentate fashion at a controllable link-er/MOP ratio. The heating of the kinetically trapped molecules leads to the formation of gels with similar colloidal networks but different extrinsic porosity. This strategy allows us to design the molecular-level networks and the resulting porosities even in the amorphous state.

Biomechanical Analysis and Design Method for Patient-Specific Reconstructive Implants for Large Bone Defects of the Distal Lateral Femur

This study aims to develop a generalizable method for designing a patient-specific reconstructive scaffold implant for a large distal lateral femur defect using finite element (FE) analysis and topology optimization. A 3D solid-core implant for the distal femur defect was designed to withhold the femur load. Data from FE analysis of the solid implant were use for topology optimization to obtain a ‘bone scaffold implant’ with light-weight internal cavity and surface lattice features to allow for filling with bone material. The bone scaffold implant weighed 69.6% less than the original solid-core implant. The results of FE simulation show that the bone repaired with the bone scaffold implant had lower total displacement (12%), bone plate von Mises stress (34%), bone maximum first principal stress (33%), and bone maximum first principal strain (32%) than did bone repaired with bone cement. The trend in experimental strain with increasing load on the composite femur was greater with bone cement than with the bone scaffold implant. This study presents a generalizable method for designing a patient-specific reconstructive scaffold implant for the distal lateral femur defect that has sufficient strength and space for filling with allograft bone.

Interaction between β-lactoglobulin and EGCG under high-pressure by molecular dynamics simulation

The binding between β-lactoglobulin and epigallocatechin gallate (EGCG) under the pressure of 600 MPa was explored using molecular docking and molecular dynamics (MD) simulation. EGCG bound mainly in two regions with site 1 in internal cavity of the β-barrel and site 2 on the surface of protein. 150 ns MD was performed starting from the structure with the optimal binding energy at the two sites in molecular docking, respectively. It was found that the protein fluctuated greatly when small molecule bound to site 2 at 0.1 MPa, and the protein fluctuation and solvent accessible surface area became smaller under high-pressure. The binding of small molecules made the protein structure more stable with increasing of α-helix and β-sheet, while high-pressure destroyed α-helix of protein. The binding energy of small molecules at site 1was stronger than that at site 2 under 0.1 MPa, with stronger van der Waals and hydrophobic interaction at site 1 while more hydrogen bonds were present at site 2. The binding energy of both sites weakened under high-pressure, especially at site 1, causing the binding force to be weaker at site 1 than that at site 2 under high-pressure.

Pressure Adaptations in Deep-Sea Moritella Dihydrofolate Reductases: Compressibility versus Stability

Proteins from “pressure-loving” piezophiles appear to adapt by greater compressibility via larger total cavity volume. However, larger cavities in proteins have been associated with lower unfolding pressures. Here, dihydrofolate reductase (DHFR) from a moderate piezophile Moritella profunda (Mp) isolated at ~2.9 km in depth and from a hyperpiezophile Moritella yayanosii (My) isolated at ~11 km in depth were compared using molecular dynamics simulations. Although previous simulations indicate that MpDHFR is more compressible than a mesophile DHFR, here the average properties and a quasiharmonic analysis indicate that MpDHFR and MyDHFR have similar compressibilities. A cavity analysis also indicates that the three unique mutations in MyDHFR are near cavities, although the cavities are generally similar in size in both. However, while a cleft overlaps an internal cavity, thus forming a pathway from the surface to the interior in MpDHFR, the unique residue Tyr103 found in MyDHFR forms a hydrogen bond with Leu78, and the sidechain separates the cleft from the cavity. Thus, while Moritella DHFR may generally be well suited to high-pressure environments because of their greater compressibility, adaptation for greater depths may be to prevent water entry into the interior cavities.

Explainable Graph Neural Networks for Organic Cages

The development of accurate and explicable machine learning models to predict the properties of topologically complex systems is a challenge in material science. Porous organic cages, a class of polycyclic molecular materials, have potential application in molecular separations, catalysis and encapsulation. For most applications of porous organic cages, having a permanent internal cavity in the absence of solvent, a property termed “shape persistency” is critical. Here, we report the development of Graph Neural Networks (GNNs) to predict the shape persistence of organic cages. Graph neural networks are a class of neural networks where the data, in our case that of organic cages, are represented by graphs. The performance of the GNN models was measured against a previously reported computational database of organic cages formed through a range of [4+6] reactions with a variety of reaction chemistries. The reported GNNs have an improved prediction accuracy and transferability compared to random forest predictions. Apart from the improvement in predictive power, we explored the explicability of the GNNs by computing the integrated gradient of the GNN input. The contribution of monomers and molecular fragments to the shape persistence of the organic cages could be quantitatively evaluated with integrated gradient. With the added explicability of the GNNs, it is possible not only to accurately predict the property of organic materials, but also to interpret the predictions of the deep learning models and provide structural insights to the discovery of future materials.

Optimization Design of the Lower Rocker Arm of a Vertical Roller Mill Based on ANSYS Workbench

The lower rocker arm is an important part of the vertical roller mill and its lightweight design is of great significance for reducing the mass and production cost of the roller mill. Firstly, the strength and deformation distribution of the lower rocker arm under working load were analyzed by ANSYS Workbench to determine the maximum stress and maximum deformation. The parts with large strength margin were used as the basis for the optimal design. During the analysis, firstly, the arm body of the lower rocker arm was determined part of the lightweight design. Secondly, the mass of the lower rocker arm was taken as the optimization target, the stress and displacement generated by the load of the lower rocker arm were taken as the constraint conditions, the structural size of the internal cavity of the lower rocker arm was taken as the optimization design parameter, and the mathematical model of the optimization design was established. Finally, the structural size of the internal cavity of the lower rocker arm was optimized by using the response surface optimization module and multi-objective genetic algorithm in ANSYS Workbench. The optimum results show that, compared with the original design model, the lower rocker mass was reduced by 346.3 kg and the decrease was about 5.29%, while the strength and deformation were nearly unchanged. Therefore, by optimizing the design, the material is saved and the cost is reduced, which can provide a reference basis for the design and light weight of the lower rocker arm.

COMBINED EXTRUSION OF GLASSES WITH A CONICAL BOTTOM. METHODOLOGY FOR CALCULATING TECHNOLOGICAL PARAMETERS OF THE TRADITIONAL PROCESS OF CONSTRAINED EXTRUSION

The methodology for calculating the energy-power and deformation parameters of the traditional process of constrained extrusion of glasses with a conical bottom part, including preliminary obtaining by molding the outer conical section of the bottom part of the product and the subsequent reverse extrusion of the glass with an internal cavity of the required geometry, is presented. The extrusion of both non-hardening and hardening material is considered. In the latter case, the account of the hardening of the extruded material is described in detail. The above formulas allow us to determine such important parameters of the stamping process as total and specific deforming force, maximum pressure on the die wall, and an increase in the yield stress.