Rod Material Research Articles

Analysis of scoliosis rod deformation after cutting with a surgical rod cutter.

Scoliosis is a complex multi-dimensional deformity of the spine that is common in children and adults. Of the various treatments for scoliosis, one is posterior spinal fusion with instrumentation. The rods typically used are composed of titanium or cobalt-chrome. Rods are cut during surgery, which causes rods to be deformed on the cut end. Inducing rod deformation raises concerns about deformed end influencing the stability of the rod-tulip-set screw interface. This study examines rod deformation from the rod cutter. This study was performed using photogrammetry, a technique allowing the creation of three-dimensional (3D) models from photographs. Rod materials included titanium (Ti) and cobalt chrome (CoCr). Three different diameters, 4.75mm, 5.5mm, and 6.0mm, were analyzed for each rod material. Five rods of each material and diameter were used for these groups, totaling 30 rods for the study. Photogrammetry was used to create a 3D rendering of the cut end of the rods. The parameters measured included local angle of deformation at each mm away from the cut, as well as roundness of the cross section. Means and standard deviations were taken for each measurement. A two-way ANOVA analysis and a Tukey post-hoc analysis were used for statistical analysis. Five rods in each rod group resulted in the analysis of 30 rods. Deformation from the rod cutter resulted in more angular deformation in the CoCr rods than the Ti rods. The CoCr rods also had lower cross-sectional roundness measurements. The 6.0-mm rods had significantly more angular deformation as well as lower roundness measurements compared to the smaller diameter rods. The 4.75-mm and 5.5-mm diameter Ti rods showed deformation up to 4mm from the cut end, while the 6.0-mm Ti rods, and all the CoCr rods, showed deformation 5mm from the cut end. The data from this study offer information about the amount of deformation present at the cut end of spinal rods. There was a difference in the angle of deformation as well as roundness along the length of the rod's cut end. Placing the deformed portion of the rods within a screw tulip theoretically increases the risk of failure of the rod-screw interface. Based on these data, to decrease the risk of construct failure, we recommend leaving at least 4mm of rod between the cut end in 4.75mm and 5.5-mm Ti rods, and 5mm in CoCr rods and 6.0-mm Ti rods.

Numerical study of the fuel rod melting and molten material migration behavior using the MPS method

The catastrophic consequences of nuclear reactor core meltdowns necessitate a comprehensive understanding of fuel rod behavior during severe accidents. This study employs the moving particle semi-implicit (MPS) method to simulate fuel rod melting and molten material migration, capturing complex phenomena such as phase changes, chemical reactions, and fluid dynamics. The developed MPS code integrates models for heat transfer, eutectic reactions, and surface tension, allowing for detailed three-dimensional simulations. Validation of the code is achieved through comparisons with analytical solutions and experimental data from the FROMA experiments. Simulations of Al–Zn substitute material rods show accurate temperature responses and phase transitions, highlighting the impact of radiation heat transfer and molten pool depth on melting behavior. Additional simulations of a single rod and a 2 × 2 rod bundle in a pressurized water reactor under extreme conditions reveal the significant role of atomic diffusion. Mass transfer between the cladding and fuel pellet expands the melting area and facilitates the formation of low-melting-point substances. The high-temperature behavior of the rod bundle demonstrates characteristic patterns, including the downward migration of molten zirconium and the dissolution of unmelted cladding. Analysis of molten UO2 migration within the rod bundle channel illustrates the influence of initial temperature and volume on migration dynamics and Zr cladding dissolution rates. This study offers valuable insights into understanding and mitigating the risks associated with core meltdowns, thereby enhancing nuclear reactor safety.

A Biomechanical Analysis of Instrumentation Constructs During Vertebral Column Resection: Stability When You Need It!

Biomechanical Testing. Investigate the optimal construct for stabilization of the spine during vertebral column resection (VCR). VCR is a powerful technique for achieving correction in severe cases of spinal deformity. However, this also creates an unstable spine which requires stable fixation to prevent iatrogenic neurologic injury. It is common practice to place a temporary unilateral rod configuration to achieve this stability during surgery but no study to date has investigated the optimal construct configuration. A unilateral VCR model representing an acute 50° kyphotic deformity with a standardized 30mm resection was created. Three conditions underwent testing: 1) Rod material and diameter, 2) rod configuration, and 3) number of fixation points. Six unique samples were tested in each group in both flexion-extension. Prior to testing a 10N preload and underwent cyclical testing in flexion/extension. System stiffness was calculated and compared across groups. Assessment of rod size and composition using a single screw construct (2 total screws) demonstrated that for Titanium (Ti) rods, increasing rod size significantly increased the construct stiffness (P=0.001). Although Cobalt-chromium (Co-Cr) rods where significantly stiffer than the corresponding sized Ti rods, there was no significant difference between rod diameters for Co-Cr (P=0.98). However, when tested using a dual screw (4 total screws) construct, these constructs were significantly stiffer than the corresponding single screw constructs (P<0.0001). Of the various rod configurations, the dual rod demonstrated the greatest stiffness (34.8±2.1N/mm; P<0.0001). Surgical construct stiffness during a VCR is multifactorial. Larger rod diameter, increased number of fixation points, stiffer rod material, and increased number of rods across the resection site increase the construct stiffness. With minimal points of fixation using Co-Cr rods, increasing rod diameter does not impart greater construct stiffness unless additional fixation points are included.

Electrochemical Oxidation of Glyphosate Using Graphite Rod Electrodes: Impact of Acetic Acid Pretreatment on Degradation Efficiency

The uncontrolled use of herbicides such as glyphosate (GLY) (N-phosphonomethylglycine) in agricultural production has resulted in its presence in water bodies and in negative impacts on the environment and public health. On the frame of understanding the interaction between GLY and graphite rod surfaces, this contribution relies on the study of electrochemical responses of different GLY concentrations by cyclic voltammetry under both open and closed-circuit conditions. Furthermore, the effect of the electrodes’ electrochemical pretreatment with acetic acid on the double-layer capacitance and the subsequent surface functionalization of the graphite rod materials were evaluated. The increment in GLY concentration showed a decrease in the electrochemical oxidation response associated with the adsorption of the contaminant on the surface of the graphite rod electrode and the concomitant blockage of the active sites. Electrochemical pretreatment of the electrodes with acetic acid and GLY concentration play crucial roles in electric double-layer formation due to their ability to interact with both positive and negative electrical charges. By means of optical microscope observations and Fourier Transform Infrared Spectroscopy analysis, it was possible to detect the formation of oxygenated functional groups on the electrode surfaces after the electrochemical pretreatment. Through a 23 factorial design analysis in repetition, the factors significant in the degradation of GLY were identified. The high degradation of GLY with the pretreated electrodes can be attributed to the preferential adsorption of the zwitterionic molecule at the interface, which allowed great direct oxidation of the contaminant on the anode’s surface.

Temperature and Physicochemical Properties of Abnormal Heating Composite Insulators.

Abnormal heating will reduce the insulation performance of composite insulators or even cause insulator fracture, and the abnormal heating phenomenon is more serious under high-humidity conditions. Therefore, in this paper, the voltage withstand test of abnormal heating composite insulators caused by aging and damp sheath, decay-like core rod, and contamination were carried out under different ambient humidity. The heating and discharge of composite insulators were observed by infrared thermal imager and ultraviolet imager, and its temperature characteristics were analyzed from the aspects of heating range, heating shape, and temperature difference. In addition, in order to study the abnormal heating mechanism of composite insulators, the micro-morphology, chemical groups and dielectric properties of the silicon rubber of composite insulators with aging and damp sheath and the decay-like core rod were also measured. It is found that the temperature characteristics of the three types of abnormal heating composite insulators are different, and the temperature difference increases with the increase of humidity. The deterioration of silicone rubber and core rod material is the internal reason for the abnormal heating of composite insulators, and high-humidity conditions will exacerbate the heating phenomenon.

Longitudinal wave propagation in FG rods under impact force

A well-known fact is that one-dimensional wave analysis is the theoretical basis of the famous Hopkinson bar dynamic testing technique. The current one-dimensional wave theory is mostly confined to the slender rods of isotropic materials. It is not easy to obtain an analytical solution to the wave equation of an anisotropic rod. In this work, rods with both elastic modulus and density graded in the length direction are presented and analyzed. The one-dimensional variable coefficient wave equation corresponding to the functionally graded rod is constructed and converted into a second-order variable coefficient partial differential equation using the Laplace approach. Then, the details of solving the partial differential equation of the second-order variable coefficients are given. It is worth noting that here we construct a variable coefficient equation that satisfies the form of Euler's equation. It is still difficult to obtain analytical solutions for other equations that do not satisfy this form. Subsequently, studies of the wave propagation characteristics of rods with different graded configurations are carried out. The theoretical results show that the wave propagation behavior and post-impact vibration of the rod are significantly influenced by the graded configuration. It is possible to adjust not only the impact response at the end but also the impact response in the middle of the rod by optimizing the design of the rod's graded configuration.

Investigation of Impact Contact Force Testing and Damage Analysis on Potatoes

To investigate the influencing factors and intrinsic relationships between potato impact force and impact damage during potato soil separation, a testing system for potato impact force was established. The impact force test system is composed of a base, a height adjustment device, a simple separation screen, a soil storage tank, an impact force sensor, and so on. By allowing potatoes to fall freely to simulate the collision process, impact force data are collected, and a high-speed camera is used to locate the impact position and analyze the degree of damage. Through the response surface analysis method, the influencing factors and laws of the impact force and impact damage during the collision process between potatoes and rods under soil and no-soil conditions were studied. The results of the response surface analysis indicate that when the screen inclination is within the range of 14.12° to 14.77°, falling height ranges from 453.83 mm to 500 mm, screen rod spacing falls within 36.50 mm to 40 mm, and the screen rod material is rubber. Potatoes can still be at a relatively low damage level when enduring a large impact force. This study has significant implications for reducing potato impact damage during harvesting, enhancing economic benefits in the potato industry, and advancing the technical level of potato harvesting equipment. In the future, based on the results of this study, further exploration can be made to optimize the design of potato harvesting equipment so as to better reduce the damage to potatoes during harvesting and subsequent processing processes and promote the sustainable development of the potato industry.

Investigation on in-situ tensile behaviors of 6061 aluminum alloy fabricated by wire additive friction stir deposition

Rod based additive friction stir deposition (R-AFSD) offers unique advantages for the integrated manufacturing of aluminum alloy near-net-shape large parts. However, the deposition process often faces issues like thick ends of raw material rods and difficulties in continuous feeding. In this study, wire based additive friction stir deposition (W-AFSD) was used for the solid state deposition of 3 mm diameter 6061 aluminum alloy wire. The microstructure evolution and mechanical properties of the deposit along the build direction were systematically characterized, clarifying the recrystallization mechanism and isotropy of the mechanical properties. In-situ scanning electron microscopy (SEM) and electron backscattered diffraction (EBSD) were used to study the deformation behavior of the deposit during in situ tensile testing, revealing a cooperative deformation mechanism involving grain rotation and intragranular slip. Results show that during in-situ tensile testing, the average rotation angle of five selected grains is 6.90°. Additionally, deposits with numerous grain boundaries due to recrystallization can hinder dislocation movement and pin the slip system within the grains during tensile testing. Due to the synergy of these mechanisms, the yield strengths of the longitudinal and transverse samples of the deposit are 183 MPa and 190 MPa, respectively, much higher than previously reported values. This article introduces a new solid state additive manufacturing method, offering new insights for efficient, high-strength continuous additive manufacturing of aluminum alloys and their deformation mechanisms.

Investigation on the influence of electrospark deposited 718 alloy coating on the penetration performance of 93 W rod

A ballistic experiment on a semi-infinite RHA target impacted by two thicknesses clade 93 W rods (200 μm 718 alloy and 400 μm 718 alloy) with an impact velocity of 1500 ± 50 m/s is conducted to investigate the influence of 93 W surface deposited coating on penetration performance. Moreover, the findings are compared with those of an unclad 93 W rod. This study aims to provide a comprehensive microstructural overview of the penetration process, including the solid-state penetrator flow and the exchange interaction mode of rod and target (R.T.) materials, using optical metallography and electron microscopy. Results indicate that the coating area is composed of approximately equiaxed or short columnar cellular crystals. Furthermore, a metallurgical fusion layer is formed between the substrate and the coating, ensuring excellent bonding strength of the coating. No significant difference in the rheological mode is found between the interfaces of the 200 μm 718 alloy and 93 W R.T. materials, while the 400 μm 718 alloy forms a barrier mix zone at the interface between the R.T. This phenomenon alters the exchange mode of the target material and affects the interface flow mechanism. The barrier mix zone also acts as a solid-state lubricant at the interface, reducing the resistance to the rod's penetration. The average penetration depth of the 400 μm clad rod is 6.89 % higher than that of the 93 W rod. This finding reveals the clad material enhances the rod's performance and provides self-lubricating characteristics.

PROFILING THE SURFACE OF THE PIN HOLE IN THE PISTON BODY

Minimization of the mass of the piston kit, which consists of three main parts - piston, pin and connecting rod, is connected, among other things, with the possibility of reducing the diameter of the steel pin. On the other hand, a decrease in its diameter inevitably leads to an increase in stresses in the piston pin hole (PPH) and possible destruction. It is known that reducing the mass of the piston set from 5 to 20% leads to an increase in the output parameters of the internal combustion engine - torque and power by 1% to 4.5%. The purpose of the study is to determine the possibility of reducing the stresses in the bearing due to the profiling of its surface while reducing the diameter of the piston pin. The research algorithm is presented, which consists of building a geometric model of the piston assembly, loading with excessive pressure taking into account the plasticity of the material, modifying the geometry of the PPH and checking the stresses of the loaded state. The conventional piston model has the following geometry: diameter – 80 mm; height – 60 mm; compression height – 30 mm; the diameter of the finger hole is 18 mm; the distance between the bumps is 28 mm. Piston material – aluminum-based alloy – AISI 2014-0, pin and connecting rod material – AISI 1020 steel. Pressure loading conditions: taking into account plasticity – nonlinear, harmonic, 2 cycles, maximum amplitude – 8 MPa; test - static, 6.5 MPa. A crumpling zone with residual deformations was detected in the PPH, the maximum final deformation practically does not differ in the first and second load cycles (0.0081 vs. 0.0084). Residual deformations occur 1/3 of the length from the inner edge of the head. The absolute residual deformations are given in the form of a sweep of the change in the PPH radius. The maximum value is about 0.04 mm. This result is the basis for modifying the geometry of the surface of the finger hole. The modified geometry of the PPH is obtained by boring the cylindrical surface with a profile modeled by the appropriate spline on the geometric model. The boring axis is offset by 0.02 mm from the PPH axis. Verification modeling showed that the averaged loads on the edge of the model are 143 MPa for the cylindrical and 107 MPa for the modified PPH (-25% for the modified profile).

COOLING OF CONTROL RODS AND SPECIFICATION OF CRITICAL TEMPERATURES TO JUSTIFY SAFE OPERATION

The paper analyzes the cooling conditions of the control rods in the mixed core of the WWER-1000 reactor containing fuel assemblies of different vendors (TVSA, WFA/RWFA). The coolant heat-up in the guide thimbles due to own energy release in control rod materials and control rod temperatures required to justify safe operation were calculated for the most conservative case, when the core consists only of TVSAs with a standardized guide thimble inlet plug of NCCP. The energy release was obtained using the calculation method for the boron carbide absorber (B4C), dysprosium titanate (Dy2O3·TiO2), control rod cladding (42CrNiMo), water gap between the cladding and the guide thimble and in the guide thimble (zirconium alloy), fully immersed and 70% immersed RCCA 10th control group. The highest calculated energy release will be observed in fully immersed control rods with boron carbide material at the height position corresponding to the zone of maximum neutron fluence and will be 43.8 W/cm3. The maximum energy release of the 70% immersed (from the bottom of the core) 10th control group is 29.4 W/cm3 for fresh B4C. For the condition of the reactor facility at which the temperatures in FA guide thimbles are maximum, for a "fresh" control rod characterized by maximum energy release in the neutron-absorbing material, the maximum coolant heat-up in the guide thimbles does not exceed 28.9 °C, with the maximum coolant heat-up in FAs being 44 °C, and the maximum control rod cladding temperature not exceeding 335.6 °C at a coolant saturation temperature of 345.8 °C, which indicates that there will be no coolant boiling in the guide thimbles under operation. The maximum temperature typical for the central part of the control rod absorber and for the most conservative calculation for a "fresh" absorber is 529.6 °C, which is significantly lower the melting point of boron carbide, which is ~2350 °C. The maximum calculated temperature in the contact zone of the B4C absorber with control rod cladding is 348 °C. The performed calculations and further analysis of the results confirm that during operation of the RCCA control rods with both “fresh” and “burned-up” B4C, there will be no boiling of the coolant and melting of the absorber in the central part of the control rod. This means that the VVER-1000 core with TVSAs and WFAs/RWFAs and the RCCA rods are reliably cooled.

Structural Optimization of a Giant Magnetostrictive Actuator Based on BP-NSGA-II Algorithm

This study introduces an integrated structural optimization design method based on a BP neural network and NSGA-II multi-objective genetic algorithm. Initially, a two-dimensional axisymmetric finite element model of the Giant Magnetostrictive Actuator (GMA) was established, and the coupling simulation of the electromagnetic field, structural field, and temperature field was conducted to obtain the GMA’s performance parameters. Subsequently, the structural parameters of the GMA magnetic circuit, including the magnetic conducting ring, magnetic conducting sidewall, magnetic conducting body, and coil, were used as inputs, and the axial magnetic induction intensity, uniformity of axial magnetic induction intensity, and coil loss on the Giant Magnetostrictive Material (GMM) rod were used as outputs to establish a back propagation (BP) neural network model. This model delineated the nonlinear relationship between structural parameters and performance parameters. Then, the BP-NSGA-II algorithm was applied to perform multi-objective optimization on the actuator’s structural parameters, resulting in a set of Pareto optimal non-dominated solutions, from which a set of optimal solutions was obtained using the entropy weight method. Finally, simulation analysis of this optimal solution was conducted, indicating that under a 5 A power supply excitation, the maximum axial magnetic induction intensity on the optimized GMM rod increased from 0.87 T to 1.12 T; the uniformity of axial magnetic induction intensity improved from 93.1% to 96.5%; and the coil loss decreased from 7.79 × 104 W/m3 to 4.97 × 104 W/m3. Based on the optimization results, a prototype actuator was produced, and the test results of the prototype’s output characteristics proved the feasibility of this optimization design method.

Fully Consolidated Deposits from Oxide Dispersion Strengthened and Silicon Steel Powders via Friction Surfacing

Abstract The objective of this work is to study the ability of friction surfacing to deposit metal alloys that are difficult to process with traditional methods. Creep and neutron irradiation resistant oxide dispersion strengthened (ODS) materials cannot be produced via conventional casting route due to insolubility of the oxidic and metallic alloy constituents, causing unintended inhomogeneous oxide dispersion and material behavior. Increasing silicon content of Iron-Silicon (Fe-Si) improves electromagnetic properties but embrittles the material significantly and the fusion based manufacturing methods unable to process this steel. The solid-state nature of the friction surfacing process offers a potential alternative processing route to enable wider usage of difficult to process alloy systems. Both ODS and Fe-Si materials are available in powder forms. While the existing literature in friction surfacing focuses on depositing composites by incorporating small quantities powders through holes in consumable rod, this is a first study that shows a large charge of powder can be converted to a homogeneous fully consolidated deposit in friction surfacing. A novel methodology is used that incorporates the high portion of powder feedstock into hollow consumable friction surfacing rods (up to 35% volume fraction). It was found that fully consolidated deposits can be produced with powder feedstocks using proposed methodology. A recrystallized, homogeneous, equiaxed microstructure was observed in Fe-Si 6.8 wt% and a new generation FeAlOY ODS alloy deposits processed with hollow stainless-steel friction surfacing rods. Both powder and rod material plasticize and deposit without bulk intermixing.

Stress Wave Propagation in a Rayleigh-Love Rod with Sudden Cross-Sectional Area Variations Impacted by a Striker Rod.

This paper presents an in-depth study of the stress wave behavior propagating in a Rayleigh-Love rod with sudden cross-sectional area variations. The analytical solutions of stress waves are derived for the reflection and transmission propagation behavior at the interface of the cross-sectional area change in the rod, considering inertia and Poisson's effects on the rod material. Examples solved using the finite element method are provided to verify the correctness of the analytical results. Based on the forward analysis of Rayleigh-Love wave propagation in a rod impacted by a striker rod, an impact-echo-type nondestructive testing (NDT) method is proposed to conduct defect assessment in rod-type structural components with sudden cross-sectional area changes within a cover medium. This proposed NDT method can identify the location, extension, and cross-sectional area drop ratios of an irregular zone in the rod to be inspected.

УПРУГОПЛАСТИЧЕСКИЙ ИЗГИБ

Within the framework of the planar cross-section hypothesis, the construction of calculation formulas for determining stresses and deformations in cross- sections of an elastoplastic member under conditions of planar transverse bending is considered. The rod material works according to a bilinear tensile pattern and resists both tension and compression equally. The cross-section of the member, which is constant along its length, has one vertical spine of symmetry. The condition of ultimate equilibrium of an elastoplastic rod is recorded. Calculation formulas for normal stresses on platforms in the cross-sections of the member, for shear stresses, for normal stresses on horizontal platforms when loading a member with a distributed load are given. curvature of the curved axis of the rod on the elastic and elastoplastic sections of the rod is determined. Differential equations of the curved axis of the rod on the elastic and elastoplastic sections of the rod are given. The residual normal and shear stresses are determined after the member has been completely unloaded. The differential equations of the curved axis of the member after it has been completely unloaded are recorded. The obtained design relations can find practical application in the design of an elastoplastic member from both the strength condition and the stiffness condition.

The Influence of Insertion Depth of Inorganic Materials on Solidification Microstructure and Segregation of 2.5-ton 42CrMo Ingot

In this work, a novel internal heat absorption technology using inorganic material rods is employed during the solidification process of steel ingots, aiming to control their solidification and improve the quality of the final product. The study investigates the effect of the insertion depth of inorganic materials on the solidification microstructure and macrosegregation of 2.5-ton 42CrMo ingots. The mechanical properties of samples from the product are also tested. A numerical simulation model for casting 2.5-ton ingots is established and implemented in Ansys Fluent fluid simulation software, with inorganic material rods set at different preset depths. The simulation explores the physical processes of the melting and floating of inorganic materials in molten steel, as well as their effects on the temperature and flow fields of the material. The results show that deeper insertion of inorganic materials (200 mm from the hot top) reduces the tendency for macrosegregation compared to that at the insertion depth of 100 mm. Specifically, the positive segregation area decreases by 10.35%, while the negative segregation area decreases by 15.32%. Moreover, deeper insertion results in a significant refinement of the solidification microstructure, ultimately enhancing the mechanical properties of the products machined from the ingots (i.e., the yield strength increased by 4.7%). The numerical simulation results indicate that as the placement depth of inorganic materials in the ingot mold increases, the cooling effect becomes more significant, the flow area of molten steel initiated by the inorganic materials expands, and the linear velocity of the double-circle flow increases. This further explains why the solidification quality of the ingots improves with the increasing placement depth of inorganic materials.

Temporal Shape Changes of Pedicle Screw-rod Constructs After Lumbar Interbody Fusion.

Retrospective multicenter study. To examine the shape change of screw-rod constructs over time after short-segment lumbar interbody fusion and to clarify its relationship to clinical characteristics. No study has focused on the shape change of screw-rod constructs after short-segment fusion and its clinical implications. One hundred eight patients who had single-level lumbar interbody fusion with pedicle screws and cages were enrolled. Three-dimensional (3D) images of screw-rod constructs were generated from baseline CT on the day after surgery and follow-up CT and were superposed on the right and left side, respectively, using the iterative closest point algorithm. The shape change was quantitatively assessed by computing the median distance between the 3D images, which was defined as the shape change value. Among the 5 time-course categories of follow-up CT (≤1, 2-3, 4-6, 7-12, and ≥13 months), the shape change values were compared. The relationships between the shape change values and clinical characteristics, such as age, CT-derived vertebral bone mineral density, screw and rod materials, and postoperative interbody fusion status, cage subsidence, and screw loosening, were evaluated. A total of 237 follow-up CTs were included (≤1 [34 scans], 2-3 [33 scans], 4-6 [80 scans], 7-12 [48 scans], and ≥13 months [42 scans]) because many patients underwent multiple follow-up CTs. There were significant differences in shape change values among the time-course categories ( P <0.001 in Kruskal-Wallis test). Most shape changes occurred within 6 months postoperatively, with no significant changes observed at 7 months or more. There were no significant relationships between the shape change values and each clinical characteristic. The temporal shape changes of screw-rod constructs following short-segment lumbar interbody fusion progressed up to 6 months after surgery but not significantly thereafter.

3D-printed tool for creating standardized burn wounds in ex vivo skin tissues

IntroductionThe development of biomaterials and medical devices for burn wound treatment necessitates thorough investigation through in vitro/ex vivo models before transitioning to animal studies. Establishing a standardized and high-throughput burn wound model in ex vivo skin presents a considerable challenge. Our objective was to address this challenge by developing a practical and cost-effective 3D-printed burn wound tool capable of uniformly inducing burns in 12 skin samples simultaneously. Material and methodsUtilizing Autodesk Inventor software, we designed a 3D model comprising a plate-base component (PBC) and a rod-base component (RBC). The design was exported as a Standard Triangulation Language (STL) file, processed through "Slicer" software to generate a G-code file tailored for 3D printing. ResultsThe Rod-Base component underwent iterative design modifications to optimize weight, airflow, and material consumption, resulting in a final design featuring a unique star shape for enhanced airflow. Simultaneously, the Plate-Base component design evolved to enable easy and secure plate placement, demonstrating compatibility with 12-well plates. The average production time for the model was 14.5 h, with a production cost of approximately $20 (USD), covering printing material and steel rods. ConclusionIn conclusion, this study provides valuable insights into the required equipment and software, empowering researchers to efficiently produce their accurate and cost-effective 3D-printed tool for controlled and reproducible burn wound creation in ex vivo viable skin tissues.

Research and Validation of CF/PEEK-Based Truss Rod Crimping and Pultruding Process for On-Orbit Isoform Forming.

A crimping and pultruding forming process for truss rods using Carbon Fiber (CF)/Polyether-Ether-Ketone (PEEK) prepreg tape as the raw material is proposed to address the problem of continuous manufacturing of space trusses on orbit. The proposed process provides material rods for continuous truss manufacturing. Through numerical simulation and experimental verification, the effects of relevant parameters on the forming process are determined, an efficient method of rod curl pultrusion, in-rail, equal material forming is proposed, and the structural configuration of the rod curl pultrusion forming mold is determined. The equivalent macroscopic mechanical properties of unidirectional CF/PEEK prepreg strips are considered, and the rod-forming process is investigated. Rod samples with different process parameters are prepared, and several tests are conducted on them. The results show that the forming load pull is negatively correlated with the temperature at the same forming speed, and forming speed is positively correlated with the forming load pull at a certain temperature. Temperature and speed affect the surface quality of the rod, the density of the material filling, and the mechanical properties of the rod. The optimal forming process parameters are determined through numerical simulation and experimental verification. The developed molding technology has the advantages of high efficiency, low energy consumption, and high integration. It reduces manufacturing costs and improves manufacturing efficiency, so it can serve as a new and effective solution for the manufacturing of high-performance truss rods in the aerospace field.

Microstructure, mechanical properties, and strengthening mechanisms of ultra-high strength Al-Zn-Mg-Cu alloy prepared by continuous extrusion forming process

In recent years, the strategy of obtaining ultra-high strength bulk Al-Zn-Mg-Cu alloys materials through implementing severe plastic deformation (SPD) has emerged as the prominent trend in structural lightweight development in aerospace and transportation fields. However, the inherent poor formability makes the SPD process of high-alloying Al-Zn-Mg-Cu alloys a great challenge. In the present work, a continuous SPD process named the Conform, utilizing a rotational speed of 4 rpm and a mold preheating temperature of 300 °C, was performed on the high-alloying 7055 Al alloy and prepared rod materials with excellent mechanical properties. The results indicated that violent shear deformation accompanied by rapid temperature rise contributes to the specific grain refinement mechanism of continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX). The grain configuration formed by this cooperative mechanism is advantageous for the alloy's compatible deformation capability. As a result, a synergistic improvement in the strength and ductility of the Conformed 7055 Al alloy was obtained. Additionally, the strengthening mechanisms induced by the Conform process were quantitatively calculated, revealing that solid solution strengthening and dislocation strengthening were the primary reasons for the enhanced strength of processed alloys.