To predict the microstructure evolution and reveal the forming mechanism of Ni-based superalloy cylindrical parts during hot power spinning, a finite element method (FEM) model of deformation-heat transfer-microstructure evolution was established using MSC.Marc software. A numerical simulation was then conducted based on the secondary development of user subroutines, to investigate evolution of the microstructure of a Haynes 230 alloy cylindrical part during hot power spinning. The volume fraction of dynamic recrystallization (DRX) and the grain size of Haynes 230 alloy cylindrical parts during hot power spinning were analyzed. The results showed that the DRX of the spun workpiece was more obvious with an increase in the forming temperature, T, and the total thinning ratio of wall thickness, Ψt. Furthermore, the complete DRX microstructure with fine and uniform grains was obtained when T $$ \geqslant$$ 1 100 °C and Ψt $$ \geqslant$$ 56%, but the grain size of the spun workpiece decreased slightly with an increase in the roller feed rate, f. The experimental results conformed well with simulation results.

Bimetal tubes have useful applications in various industries where service conditions demand more different requirements in the tube core than its outside surface. The recent use of electromagnetic forces to deform or join metallic workpieces at high speeds has undergone rapid growth for materials processing. However, to date, no sufficient systematic understanding of the underlying principles of a subsequent high-speed electromagnetic tube bulging process to manufacture bimetal tubes has been gained. In this work, magnetic pulse cladding of Al/Fe clad bimetal tubes was analyzed by finite element modeling (FEM) using ANSYS software. The validity of FEM analyses was first confirmed by experiments in terms of the deformed shape. Second, the effect of cladding parameters (such as axial feeding being the dominant factor in the multi-step process) on the bulging and thinning behavior of the Al clad tube was presented in detail. Both the numerical simulation and experimental results show that no more than 70% of the bulging-coil length is an appropriate amount for the feeding length to prevent defects from being introduced by non-uniform deformation in the transition zone of the Al clad tube. The distributions of the magnetic flux line, magnetic force, and plastic strain in different cladding steps were then analyzed. It was concluded that during the multi-step cladding process, there was an uneven distribution of the magnetic field force along the transition zone. Consequently, inharmonious plastic deformation behavior occurs, which results in a limited acceleration of the transition zone to a certain impact velocity.

The experimental determination of stability lobe diagrams (SLDs) in milling can be realized by either continuously varying the spindle speed or by varying the depth of cut. In this paper, a method for combining both these methods along with an online chatter detection algorithm is proposed for efficient determination of SLDs. To accomplish this, communication between the machine control and chatter detection algorithm is established, and the machine axes are controlled to change the spindle speed or depth of cut. The efficiency of the proposed method is analyzed in this paper.

The first part of this study is devoted to concepts, approaches and some examples of the fourth industrial revolution. The basis of this revolution also well known as Industry 4.0 builds so called cyber-physical systems. They contain the integrated smart software systems including the internet address to enable the communication with environment as for product itself as for means of production and employees. All these enable the next level of efficiency and flexibility for both organizing and controlling of the value-creation chain over the whole lifecycle of products. In the first three chapters several Internet references and documents published by German Federal Ministry for Economic Affairs and Energy were used. Because of multiple cross references in documents, this report is written without detailed references in each paragraph of mentioned chapters. The last three chapters of the research presented undertake the short review of interdependencies between the Industry 4.0 and the well-known approach of computer-supported-cooperative-work established in the late 1980s. Long list of publications can be found in Wikipedia, and in many proceedings of ACM conferences on computer supported cooperative work (CSCW).

Fused deposition modeling (FDM) is an additive manufacturing technique used to fabricate intricate parts in 3D, within the shortest possible time without using tools, dies, fixtures, or human intervention. This article empirically reports the effects of the process parameters, i.e., the layer thickness, raster angle, raster width, air gap, part orientation, and their interactions on the accuracy of the length, width, and thickness, of acrylonitrile-butadiene-styrene (ABSP 400) parts fabricated using the FDM technique. It was found that contraction prevailed along the direction of the length and width, whereas the thickness increased from the desired value of the fabricated part. Optimum parameter settings to minimize the responses, such as the change in length, width, and thickness of the test specimen, have been determined using Taguchi’s parameter design. Because Taguchi’s philosophy fails to obtain uniform optimal factor settings for each response, in this study, a fuzzy inference system combined with the Taguchi philosophy has been adopted to generate a single response from three responses, to reach the specific target values with the overall optimum factor level settings. Further, Taguchi and artificial neural network predictive models are also presented in this study for an accuracy evaluation within the dimensions of the FDM fabricated parts, subjected to various operating conditions. The predicted values obtained from both models are in good agreement with the values from the experiment data, with mean absolute percentage errors of 3.16 and 0.15, respectively. Finally, the confirmatory test results showed an improvement in the multi-response performance index of 0.454 when using the optimal FDM parameters over the initial values.

The Gibbs free energy change for the hydrogenation of graphene nanoflakes C n (n = 24, 28, 30 and 32) and the C–H bond dissociation energy of hydrogenated graphene nanoflakes C n H m (n = 24, 28, 30 and 32; and m = 1, 2 and 3) are evaluated using density functional theory calculations. It is concluded that the graphene nanoflakes and hydrogenated graphene nanoflakes accept the orth-aryne structure with peripheral carbon atoms bonded via the most triple bonds and leaving the least unpaired dangling electrons. Five-membered rings are formed at the deep bay sites attributing to the stabilization effect from the pairing of dangling electrons. The hydrogenation reactions which eliminate one unpaired dangling electron and thus decrease the overall multiplicity of the graphene nanoflakes or hydrogenated graphene nanoflakes are spontaneous with negative or near zero Gibbs free energy change. And the resulting C–H bonds are stable with bond dissociation energy in the same range as those of aromatic compounds. The other C–H bonds are not as stable attributing to the excessive unpaired dangling electrons being filled into the C–H anti-bond orbital.

Current industrial robotic welding systems cannot achieve automated solutions for multi-layer multi-pass welding of complex joints due to the presence of non-uniform and irregular welding groove geometries. This paper presents an adaptive pass planning approach for robotic welding of such complex joints. The welding groove is first segmented considering both the variation in groove dimension and the reachability of the robot welding torch. For each welding segment, the welding passes are planned to be in accordance with welding practices, viz., keeping the same number of welding passes in each layer while maintaining consistent welding parameters. An adaptive pass adjustment scheme is developed to address the discrepancies between the simulated results and the actual welding deposition after finishing a few layers of welding. Corresponding robot paths are generated and optimized to ensure minimum joint movement subject to three constraints, viz., reachability, collision-free and singularity avoidance. The proposed approach has been simulated with the arc welding of a Y-type joint found typically in offshore structures.

Precision positioning systems driven by linear motors are vulnerable to force disturbances owing to the reduction of gear transmission. The friction, included in the disturbance, can be modeled and compensated to improve the servo performance. This paper proposes a modified Stribeck friction model (SFM) and an optimization algorithm for consistency with the positioning platform. The compensators based on the friction model and disturbance observer (DOB) are simulated. The simulation results show that as compared with the DOB compensator (the velocity recovers by 5.19%), the friction model based compensator (the velocity recovers by 10.66%) exhibits a better performance after adding the disturbance. Moreover, compensation comparisons among the Coulomb friction, traditional SFM, and modified SFM are performed. The experimental results show that the following error with modified SFM compensation improves by 67.67% and 51.63% at a speed of 0.005 m/s and 0.05 m/s, compared with the Coulomb friction compensation. This demonstrates that the proposed model, optimization algorithm, and compensator can reduce the following error effectively.

In this study, an air-bearing capacitive linear variable differential transformer (LVDT)-like contact sensor with a rounded diamond tip was mounted to a desktop machine tool to construct an on-machine (OM) measuring system. The measuring system was capable of decoding the digital signals of linear encoders mounted on the machine tool and acquiring the analog signal of the contact sensor. To verify the measuring system, experimental examinations were performed on an oxygen-free copper (OFC) convex aspheric mold with a diameter of 5 mm and a curve height of 0.46 mm. The acquired signals were processed by the implemented Gaussian regression filter (GRF), removing the tilt of measured profile, and compensating for the radius of probe tip. The profile obtained was compared to that measured using a commercially available device, and a maximum deviation of 14.6 μm was found for the rough cutting. The compensation cutting was then performed according to the form error of OM measurement. As a result, the PV form error compared with the designed profile was reduced from 19.2 μm over a measured diameter of 4 mm to 9.7 μm over a measured diameter of 3.1 mm, or a percentage improvement of 35.4% in form accuracy. Through the examination for aspheric machining, the effectiveness of the implemented OM measuring system was demonstrated, and the technical details of system implementation were presented. Further improvement was suggested to reduce the diameter of probe tip and measuring force.

Three friction welding processes are compared for temperature, stresses and strains, as well as strain rates developed in the early phases of the processes, which are essential in their successful development. These are friction stir welding (FSW), linear friction welding (LFW) and rotary friction welding (RFW). Their common characteristic is the use of friction to generate adequate energy and raise temperature locally in order to create favorable conditions for welding at the interface between two parts. Although the mode of movement is different for each one of them, welds are produced through plastic deformation. The Lagrangian and coupled Eulerian-Lagrangian numerical models developed have produced results which are in qualitative agreement with experiments and have shed a light on the commonalities of these friction welding processes.