The properties of a mechanical material depend not only on its chemical components but also on the micro/nano structures of its surface and interior. Attempts have been made in recent years to develop new surface/material functions through mechanical processes. For example, technologies to control various characteristics, such as friction, water repellency, and optical properties, have been developed by constructing micro/nano periodic structures on the surfaces of materials. Since these properties depend on the geometry of the surface morphology, micro/nano fabrication processes can produce a variety of properties. This indicates that the surface properties and material properties of portions of the materials can be controlled to reach optimal conditions required by machine product design. This technology is expected to lead to the advanced production of products integrating design, manufacturing, and materials in an organic way. Here, we call the materials and surfaces with their properties arbitrarily controlled in accordance with machine design “tailored functional materials and surfaces.”
This special issue features various studies and reports related to tailored functional materials and surfaces, and it includes 12 related papers and a review. They cover processing technologies that create and control various surface functions, such as water repellency, friction, biological and chemical reactions, and optical properties. They indicate the possibilities and future of new precision processing technologies.
We deeply appreciate all the authors and reviewers for their efforts and contributions. We also hope that this special issue will encourage further research on tailored functional surfaces.
Because of their repellent, corrosion-mitigating, anti-icing, and self-cleaning properties, superhydrophobic coatings have numerous applications from windshields to textiles. A superhydrophobic coating is defined as one having a water contact angle (WCA) greater than 150° with a surface sliding angle less than 10°, and very low hysteresis between the advancing and receding angles. Its surface exhibits the so-called “lotus leaf effect,” whereby water bounces and balls up on contact. Here, water droplets run off readily, taking along dirt and dust for a self-cleaning effect that keeps the surface dry. The chemical composition of a surface affects the WCA, which can rise to 120°, but to achieve a WCA greater than 150°, which is considered superhydrophobic, an additional micro- and nanostructural component is needed. This functional hierarchical micro- and nanomorphology is exhibited in nature by plants and insects. A superhydrophobic coating on metallic substrates promises to provide corrosion mitigation by blocking oxygen and electrolytes, which are needed for the initiation of corrosion at the surface and interface. The methods used for preparing functional superhydrophobic coatings include sol-gel processing, layer-by-layer assembly, etching, lithography, chemical and electrochemical depositions, chemical vapor deposition, electrospinning, hydrothermal synthesis, and one-pot reactions. In this work, some research studies conducted to develop robust and durable superhydrophobic coatings are discussed in detail and analyzed for possible corrosion mitigation on the surfaces of metals and alloys. Scientists, engineers, students, and other participants in automotive, aircraft, energy, defense, electronics, and other industries will benefit greatly from this work.
A dispensing nozzle is an essential mechanical element in inkjet, dot, and bioprinting. To improve the printing resolution, the inner diameter of the nozzle outlet must be as small as possible. A droplet dispensed through a hydrophilic stainless steel outlet expands on the whole outlet surface and along the side surface of the nozzle. This issue can be solved by physical surface modifications. In the present paper, a femtosecond laser micro-/nano-texturing method was developed to transform the originally hydrophilic stainless steel surface of a nozzle to a hydrophobic or superhydrophobic one. First, an AISI304 plate was used to demonstrate experimentally that, on its surface, the tailored micro-/nano-patterns were reproduced as micro-/nano-textures, making the surface superhydrophobic. Second, the technique was applied to the physical surface modification of an AISI304 stainless steel nozzle outlet by optimizing the femtosecond laser machining conditions. A high-speed camera was used to take a snapshot of the dispensed droplet from the surface-modified outlet. Finally, a line-printing experiment was performed to characterize the dispensing behavior of the stainless steel nozzles with and without physical surface modification.
Micro-actuators are used for mechanical stimulation of cultured cells in regenerative medicine and are critical components of biosensors. In this study, electrochemical polymerization is utilized to fabricate a film of poly-pyrrole (PPy) with a thickness of 10 μm. This film is peeled off from a working electrode substrate and subsequently laminated with a polydimethylsiloxane (PDMS) membrane containing holes of diameter of 5 mm. The assembled PPy film forms a membrane of PPy that can be used as a micro-actuator. This membrane is deflected upward via the application of voltages of −0.2, −0.4, −0.6, −0.8, and −1.0 V for 120 s in either NaDBS solution or cell culture solution. The primary response was an expansion in the in-plane direction with the absorption of ions in the electrolyte solution. The deflection increases with the duration of the applied voltage. Moreover, the maximum deflection that increases with the applied voltage reaches 540 μm at −1.0 V in the NaDBS solution. In the cell culture solution, the maximum deflection is approximately 400 μm for an applied voltage of −1.0 V. When the PPy membrane actuator was used in the culture solution, the time constant was 20 s to reach 63.2% of the maximum deflection. During operation, a voltage with a rectangular form and a period of 40 s was periodically applied. The operation of the PPy membrane actuator was repeated 90 times or more, although the deflection of the membrane had slight attenuation during the cycle of applied voltage. The PPy membrane exhibited adequate adhesiveness for cultured C2C12 cells. They adhered to the PPy surface and stretching of their pseudopods was observed. These cells are additionally cultured on the PPy membrane actuator. When a voltage is applied, the membrane actuator is operable while supporting cultured C2C12 cells. These cells are mechanically and electrically stimulated on the membrane that functions as a cell stimulation device.
Magnesium and magnesium-based alloys are considered ideal materials for implants in orthopedic treatment because their stiffness is close to that of human bones, and they can be absorbed gradually in the human organism. However, a major issue in their actual application is that the corrosion speed of Mg alloys is very high in aggressive environments such as the human fluids. In previous studies, many approaches have been attempted to enhance the corrosion resistance of Mg alloys. In this research, ball burnishing, a mechanical surface finishing process, is applied to improve the corrosion resistance of Mg alloys by changing its surface properties. The influence of the burnishing parameters on the corrosion resistance is investigated, and the corrosion of a treated and non-treated sample are compared. The test material used is the AZ31 Mg alloy. Firstly, a comprehensive review of the effect of burnishing on the final microstructures is reported. The influence of burnishing on grain size, work-hardened layer thickness, crystal orientation, and residual stress of the sample is discussed. Secondly, by conducting an especially designed long-term immersion test, the mass loss and surface evolution of each sample are evaluated. The experimental results indicate that, under proper processing conditions, the mass loss of the treated sample (8.8 mg) can be reduced to 36% of the non-treated one (24.2 mg). To elucidate the mechanism behind corrosion resistance enhancement by burnishing, the samples treated with the optimal processing parameters found are immersed in an aggressive solution for 1, 3, 5, and 7 days. From the results of mass loss measurement and surface structure characterization, it was found that, among pitting, general, and intergranular corrosion, pitting corrosion is the dominant corrosion mechanism. The holes enlarge because pits combine together, representing the greatest portion of mass loss. The main mechanism enhancing corrosion resistance is the size reduction of the grains on the surface induced by ball burnishing, causing a denser distribution of corrosion products in the immersion test. These corrosion products protect the material underneath accelerated corrosion.
This study aims to improve the efficiency of gas sensors with a zinc oxide (ZnO) structure by widening the surface area for reaction and using UV-activation. The silica (SiO2)-ZnO core-shell urchin-like structure is a promising candidate to achieve this aim, due to its broad surface area and electrically insulated formation. The higher resistivity of silica prevents the escape of electrons and recombination during reaction with gas; thus, improving its sensitivity. The structure was fabricated by a two-step process. First, ZnO-silica core-shell structures were produced. ZnO nanoparticles (φ≤ 34 nm) self-assembled to form a shell around a core comprising silica particles (φ5 μm). Gravity sedimentation was then used to obtain the silica particles, while the ZnO particles were obtained by dropping and drying of the suspension. Closely packed structures were obtained due to the meniscus attraction between the particles at the drying stage of the suspension. Second, ZnO urchin-like structures were synthesized on the silica particles using the hydrothermal method, with the originally placed ZnO nanoparticles as the nuclei. The method is a simple material synthesis involving the crystal growth process in a sealed container, in which substrates and precursors are stored and maintained at an elevated temperature. The obtained structure (or morphology) changed depending on the nucleation and growth conditions. The appropriate conditions were clarified through systematic experiments. Finally, the gas sensor performance was examined.
In this paper, we propose a new polishing method for diamond-like carbon (DLC) coatings using a carbon fiber brush (CFB). Surface finishing is an important process for DLC coating applications. A lapping process is widely used for attaining tetrahedral amorphous carbon (ta-C) coatings, which are a type of DLC coating containing many droplets, to obtain fine flat surfaces. The lapping process removes protuberant parts of droplets rather than the entire droplet. In this paper, we propose a new polish brush material made of carbon fiber, called CFB. Carbon fiber has both mechanical strength due to its hard carbonaceous material and flexibility due to its fiber structure. In polishing tests, CFB removed droplets from ta-C coatings and the removal effect increased with the shortening of the brush length. The surface profiles of the polished surfaces indicated that a shorter brush length yielded deep scratch marks on ta-C surfaces. Consequently, the arithmetic average surface roughness of the polished ta-C surfaces, Sa, had almost the same value as that of a non-polished surface. Here, we show the ability of CFB to remove the droplets without an increase in the surface roughness. The CFB with the longest brush length in the present study (12 mm) showed a ten-point average roughness SZJIS= 75 nm and Sa= 4.7 nm, which were 59% and 22% lower than those of the non-polished surface, respectively. Furthermore, the longest CFB removed the entire droplets whereas a shorter CFB merely removed the protuberant part of the droplets. The result indicates that CFB polishing can remove entire droplets, which result in abrasive wear or deterioration. From other polishing tests, the optimum polishing distance was determined. Shorter polishing distances could not remove droplets sufficiently whereas longer polishing distances caused deep scratches on ta-C surfaces due to the material transferred to the CFB. Accordingly, the polishing distance of 600 m showed the best surface finishing with SZJIN= 25 nm and Ra= 0.43 nm, which were 86% lower than and similar to those of the non-polished ta-C surface, respectively.
Micro-embossing using plasma printed micro-punch was proposed to form micro-groove textures into the copper substrate for plastic packaging of hollowed GaN HEMT-chips. In particular, the micro-groove network on the copper substrate was optimized to attain uniform stress distribution with maximum stress level being as low as possible. Three-dimensional finite element analysis was employed to investigate the optimum micro-grooving texture-topology and to attain the uniform stress distribution on the joined interface between the plastic mold and the textured copper substrate. Thereafter, plasma printing was utilized to fabricate the micro-punch for micro-embossing of the micro-grooving network into the copper substrate as a designed optimum micro-texture. This plasma printing mainly consisted of three steps. Two-dimensional micro-pattern was screen-printed onto the AISI316 die surface as a negative pattern of the optimum CAD data. The screen-printed die was plasma nitrided at 673 K for 14.4 ks at 70 Pa under the hydrogen-nitrogen mixture for selective nitrogen supersaturation onto the unprinted die surfaces. A micro-punch was developed by mechanically removing the printed parts of die material. Then, fine computer numerical control (CNC) stamping was used to yield the micro-embossed copper substrate specimens. Twelve micro-textured substrates were molded into packaged specimens by plastic molding. Finally, gross leak testing was employed to evaluate the integrity of the joined interface. The takt time required to yield the micro-grooved copper substrate by the present method was compared to the picosecond laser micro-grooving; the former showed high productivity based on this parameter.
In this study, we propose a new surface generation model for carbon fiber reinforced thermoplastics (CFRTP) manufactured by the long fiber thermoplastic-direct (LFT-D) method. CFRTP are considered to be a next-generation structural material because of their high productivity as well as high mechanical strength and lightness. Conversely, CFRTP have a rough surface, which does not meet the automotive outer panel standard of a “class A surface.” In the present study, we establish a surface roughness generation model based on a thermal shrinkage mismatch of thermoplastic resin to carbon fiber and non-uniform carbon fiber distribution. Furthermore, we construct a surface roughness estimation formula based on the model. In the calculation, a cross-sectional image of CFRTP is divided into many vertical segments. Subsequently, the thermal shrinkage of each segment is calculated with a standard deviation, an average, and a probability density of the amount of carbon fiber in each segment. The surface roughness of the manufactured CFRTP was measured using a surface profilometer. The result showed that the arithmetic surface roughness increased with the volume fraction of carbon fiber. We applied the surface roughness calculation to cross-sectional images of the specimens. Consequently, the estimated surface roughness showed the same tendency, in which the surface roughness increased with the volume fraction of carbon fiber. The slope of a regression line of the estimated surface roughness with respect to the volume fraction was 0.010, which was almost the same (0.011) as the slope of a regression line of the measured surface roughness. Furthermore, the estimation formula using a thermal shrinkage effective depth of 395 μm was able to estimate the surface roughness within a 3% average error. Using the estimation formula, it was predicted that the surface roughness increased with the standard deviation of the amount of carbon fiber in a segment. To confirm the reliability of the model and the formula, we measured the standard deviation of the amount of carbon fiber in CFRTP specimens, showing that the trend for CFRTP specimens matched the estimated values.
During the turning process, cast iron is directly shattered to become particles. This mechanism means the surface roughness cannot be predicted using the kinematic equation. This paper provides surface roughness predictions using two methods, the multiple regression model (MRM) and artificial neural network (ANN). Cutting parameters and vibration signals are considered input variables in both methods. This work also overcomes the common sensor position limitation (tool shank) and provides a safe and efficient solution. The prediction values from MRM and ANN show accurate results compared to the measured surface roughness, with the average error of less than 8%. Furthermore, the proposed sensor position, at the turret bed, also exhibits similar prediction accuracy to a sensor at the tool shank, hence promising feasible industrial application.
In this paper, a chemical lift-off process using acetone ink was examined to attain the easy fabrication of metallic nano/microstructures. This process consists of five steps: cleaning of the substrate, chemical stamping, metal film deposition, coating with glue, and selective peeling. Details of the hot embossing process for the cycloolefin polymer (COP) film mold fabrication and the selection of the organic solvent ink for the chemical stamping are also explained. The fabrication of several kinds of metallic nano/microstructures, such as Au line and space structures, Au square film arrays, and Au dot arrays, is demonstrated. It is shown that metal films coated on the stamped region peeled off with the glue, and a metal film shaped in the stamp’s negative pattern remained on the substrate. Acetone is effective for reducing the surface energy of the substrate and the bonding strength, resulting in selective peeling of the coated metal film.
Surface microstructures can provide various functionalities, and wettability is a typical surface property that can be controlled by the surface textures. This study attempted to fabricate hierarchical microstructures through ultrasonic-assisted face milling (UAFM) to change the surface functionality by specifically focusing on the wettability. The fabrication involved the use of an ultrasonic generating spindle and a self-designed diamond tool. The locus of the tip of the diamond tool was computed based on the equation of motion, and the micro- and macrostructures are illustrated in this paper. The structures were confirmed through observations using a white-light interferometer. The wettability on six zones of the processed area was measured, and the results indicated that the central zone of the UAFM surface became hydrophobic, whereas the edge zone became hydrophilic.
Functional films with multi-directional wavy microgrooves can be applied to reduce fluid drag in turbulent flow applications. For high-efficiency mass production of functional films through polymer imprinting, it is necessary to machine wavy microgrooves on the surfaces of metal roll molds. When wavy grooves are cut, to reduce the follow-up errors of machine tools, a very low cutting speed is normally used, but the mechanism of this cutting is still unclear. In this study, microgrooving experiments were conducted on three different workpiece materials: brass, oxygen free copper, and aluminum alloy, and their cutting mechanisms were investigated. Distinct differences in chip formation behavior and machined surface integrity were identified among these materials. Aluminum alloy was chosen as the most suitable material for roll mold fabrication. Two-directional wavy microgrooves with form accuracy on 1 μm level and surface roughness of less than 10 nm Ra were obtained.
The effects of negative rake angles on the ductile mode cutting of soda glass and sapphire were studied. In addition, the machining mechanism was studied using a groove-cutting model based on the orthogonal cutting theory. It was found that the specific cutting forces in ductile mode cutting increase on both the soda glass specimen and on the sapphire specimen when the rake angle of the tool becomes negative. The difference between the experimental data and theoretical data of the specific cutting forces becomes large when the tool has a high rake angle on the negative side. This is attributed to effects of the roundness of the edge, the effects of the roundness of the nose, and the plowing mechanism, which causes plastic flow of the work material to both sides of the groove. The specific cutting force of sapphire depends on the cutting direction against the crystal orientation. The specific cutting force of sapphire depends on the cutting direction in terms of the crystal orientation. The anisotropy of the cutting force of sapphire also depends on the rake angle of the tool.
The design of machine tools strongly depends on the materials chosen. Increasing requirements on machine tools require the joint optimization of material and design and thus also drive the development of new materials in this field. Digital technologies finally creating a digital shadow of the machine in development also enable the required co-development taking into consideration dynamic, thermal and long term influences and behavior, enabling state and health monitoring to increase the performance of the machine tool to the maximum possible. The choice of material for the different components of machine tools is today even more difficult than ever. The recent review paper by Möhring et al.  sheds light on the vast field of properties and decision opportunities of combining materials at hand with design features. In former times, cast iron was the predominant material for machine bodies and has left its footprints on the design of machine tool bodies lasting still up to now. Because massive machine bodies have been the wealth of good properties, high accuracy, stiffness, good material damping properties have been attributed to cast iron design, then with increasing strength requirements higher strength cast irons came into fashion having much less material damping and finally lead to welded frames. Today requirements of dynamics and thermal behavior change the scene again. The goal is to achieve high productivity with high accuracy, which typically is a contradiction. But increasing dynamics requires distinguishing between moving bodies and their non-moving counterparts, and opens the floor for multimaterial design. For moving parts, which have to move with high dynamics meaning, high speed, high acceleration, high jerk, light weight design prevailed with the utilization of standard materials. Because manufacturability plays a major role, the bionic structures have to be degraded to thin walled rib structures as demonstrated in Fig. 1, while in future additive manufacturing will remove that restriction and enable some real bionic structures.
Furthermore material choice has a huge impact on inertia savings which opens the door for CFRP, which becomes especially interesting, when the anisotropy of this material is exploited as shown in Fig. 2. From the manufacturability truss structures then result shown in Fig. 3.
For the nonmoving elements, the base body, cast iron, welded steel, polymer cast, and concrete are typical materials chosen. Also aluminium structures are discussed despite the fact that aluminium has only one third of the stiffness of steel, but it offers much better thermal conductivity equalizing temperature differences faster and thus reduces the warp of the structure, which typically causes larger errors than an isotropic thermal expansion. For the choice of materials no generalizable guideline exists. The question which material is the better choice is not answerable in generality, because design follows material, which means that a sound comparison requires completely new design approaches for the different materials, where the difference between metal and polymer concrete or CFRP is really large, offering different potentials. As an example, a design of a fast moving bridge of a gantry machine might be considered. The guiding of a support on this bridge with roller guidings imposes severe problems to the design due to the material mix and different thermal expansion coefficients. Thus the choice of CFRP for the bridge necessarily must be followed up by a decision of the guiding principle, where in this case aerostatic bearings were considered as the most promising possibility. Also the potentials for function integration into the material are of major interest for the material choice, as this is easily possible for low temperature castings like for mineral cast, CFRP, or concrete. This integration of functionalities actually …
Nanofibers of polypropylene were produced by a modified melt-blowing method. The manufacturing method and thermal characteristics of fabricated nonwoven-fabric nanofibers were studied. Apparent thermal conductivity was measured as an evaluation of adiabatic properties, and a prediction model was developed with computational fluid dynamics (CFD) based on a one-dimensional computer-aided engineering method. In addition, we attempted to evaluate true thermal conductivity in consideration of lateral heat dissipation during measurement by thickness. Consequently, we determined the influence of the fiber diameter and thickness of the nonwoven fabric on the thermal conductivity and demonstrated that the proposed CFD model was effective for estimating the characteristics of the thermal conductivity of the nonwoven fabric.
This paper presents the dynamic characteristics of a hybrid guideway system that employs sliding guides as the primary support and rolling guides to decrease the friction force and improve servo response. A drive table with a linear motor was fabricated, and the dynamic responses of the proposed hybrid guideway to command input and disturbances were measured. The results indicate that the developed guideway system provides high dynamic stiffness without sacrificing the accuracy of servo response. Furthermore the floating action of the table influenced the dynamic compliance of the guide in the horizontal direction.
Plastic gears are light and can be used without any lubricant, but they have low strength and an adverse effect on the environment. Therefore, a new gear that maintains these advantages while mitigating the disadvantages has been proposed. The development of sustainable and reproducible natural materials is desired to address these environmental problems. Therefore, in this study, a method was devised to extract high-quality and precise bamboo fibers using a machining center. Then, the hot press method was used to produce a novel spur gear made from only bamboo fibers, which is a green and organic machine element with a complicated shape. The present paper describes the characteristics of the proposed bamboo fiber gears, considering experimental results, including the hot press molding conditions, and the influence of fiber length on tooth bending strength, root strain, and vibration due to meshing teeth.
Spindle is one of the most important component of machine tools because spindle’s performance including thermal property and dynamic property greatly influences the accuracy and productivity in machining process. This study investigates the effect of the application of carbon fiber reinforced plastic (CFRP) to the spindle shaft on the performance of machine tool spindles. CFRP and steel spindle shafts with the same geometry were developed for fair comparison. Thermal and dynamic properties of the developed shaft and spindle unit were evaluated and compared. The experimental and simulation results showed that the CFRP spindle shaft improved the axial thermal displacement and dynamic stiffness. The axial thermal displacement was decreased to 1/3 of that of the steel spindle. The compliance was also decreased to 1/2. The design of the thermal displacement distribution around the bearing should be an important issue in the CFRP spindle for the thermal stability of the dynamic property.
Most machine tools comprise a combination of square blocks and plates for each body structure, which is not fully optimized. One reason for the nonoptimal design is that machine tool designers face difficulty in introducing curved structures to fulfill functional requirements. In this paper, completely new structures of the surface profile grinding machine have been developed, pursuing the ideal structure by defying fundamental design rules as well as by utilizing topology and shape optimization methods. The combination of fundamental techniques and state-of-art techniques enables lightweight structures that can achieve two-times higher resonance frequency, 40–50% space-saving, and 60–100% productivity improvement, compared to those with the conventional design.
Carbon fiber reinforced polymer (CFRP) utilization meets the requirements of stiffness, damping, and light weight for enhanced performance of machine tools. Stamping presses are expected to function for billions of cycles, resulting in the fatigue of the employed materials and parts. High-speed stamping presses, such as the Bruderer BSTA-200, should fulfil the increasing customer requirement of enhancing both quality and quantity of the delivered parts. Among the quickest presses currently available in the market, these BSTA presses can reach speeds up to 2000 strokes per minute (spm) with a stroke of 8 mm and still continue operating for many decades. For this project, new requirements were defined: a 25% increase of the stamping speed reaching up to 2500 spm, while maintaining the same stroke of 8 mm. The ram was redesigned by making use of CFRP, and because of its high stiffness and strength, it enabled a weight reduction of 65%. Owing to the stamping force of 200 kN and the impact of the stamping process, the material of the ram is highly strained. A major concern in utilizing CFRP in machine tools is the fatigue and change in material properties with increasing stress cycles. Therefore, the fatigue behavior of CFRP had to be validated in the very high cycle fatigue (VHCF) range. This was performed using a newly developed fatigue test bench. To complete 109 cycles within a few weeks, the testing occurred at the specimen’s resonance frequency with a constant and controlled strain of 0.1%. Aspects such as resonance frequency testing, heating of the specimen, and an accurate measuring system were considered. The specimens had to be designed and optimized for this type of testing, thus resulting in a cylindrical tube shape with a unidimensional (UD) arrangement of the fibers in longitudinal and transverse direction.
Taking into account the growing demand for sophisticated cutting tools in terms of their performance, new approaches, besides the development of the tool’s cutting edge, have to be investigated and validated by physical tests. In this study, methods of topology optimization and hybrid design are adopted for cutting tools. After a quick overview of its motivations, reduction of mass, the design of load paths, and beneficial functions within tool bodies, a structured method and its application on a long shell end mill for metal cutting is described as part of a holistic approach at the system and component levels. The manufacturing of the resulting geometry is examined for additive manufacturing. The optimized structures reduce the spindle power required, especially for acceleration to the desired speed; this, in turn, decreases the energy consumption of the process. Besides bearing static and dynamic loads, composites provide the adjustable option in process-stabilizing damping. In the field of wood cutting, the cutting forces are lower than those in the machining of metals. Here, we describe a planing tool with a large overhang and the first step in its development. The finite element analysis within the software Ansys Workbench and CompositePrep/Post (ACP), the special tool for modeling reinforced structures, are utilized for preparing the layout of the tool. To ensure the structural integrity of fiber reinforced plastic (FRP), the failure criteria proposed by Puck are applied. The overhanging planing tool is clamped on one side. It shows the principles for the development of a prototype and forms the basis for tools with even larger diameters and benefits. The underlying concept of the planing tool prototype is an innovative sandwich concept, wherein sleeves are used to join metal with carbon fiber reinforced plastic (CFRP) in a micro-forming process. Besides the abovementioned advantages, the reduction of acoustic emissions in the very noisy field of wood machining is a promising application.
In this work, an adaptive sliding mode fault-tolerant controller is proposed for a class of uncertain systems with time delay. The integral term is added to the traditional sliding surface to improve the robustness of the control system, and then a type of special sliding surface is designed to cancel the reaching mode based on global sliding mode method. Without the need for fault detection and isolation, an adaptive law is proposed to estimate the value of actuator faults, and an adaptive sliding mode fault-tolerant controller is designed to guarantee the asymptotic stability of sliding dynamics. Finally, the presented control scheme is applied to the position control of a Qball-X4 quad-rotor UAV model to verify the effectiveness.