An Overview of Possible Integration of Green Design Principles Into Mechatronic Product Development Through Product Lifecycle Management

People that work on the development of mechatronic products do not have enough data related to the end of the product lifecycle when making decisions related to the product design. Sustainable design tools in Product Lifecycle Management (PLM) systems could enable more sustainable designs with ‘greener’ decision-making. PLM tools, which are supporting designs of mechatronic products, are lacking more consideration about the product’s overall lifecycle ecological footprint. Most decisions that are made during the design phase are based on costs of materials and processes that are involved in development and manufacturing, not to the service, reuse, recycling and disposal of such products. This study will investigate the possibility of including the data related to the end of the product lifecycle. Integrating green design tools into the PLM systems would help mechatronic engineers to develop more sustainable designs. This paper will investigate the current state of the art in the area of Product Lifecycle Management systems that support design and realization of mechatronic projects. It discusses some ideas that can be used for determining a framework for data capturing of electro-mechanical product related data. This would connect decisions in earlier phases with the ones in final stages of a product lifecycle. This data can be used for the environmental footprint determination.

Numerical Simulation on Nanoparticles Integrated Laser Shock Peening of Aluminum Alloy

In this paper, numerical simulation of nanoparticle integrated laser shock peening of aluminum alloys was carried out. A “tied constraint” was used to connect the matrix and nanoparticle assembly in ABAQUS package. Different particle size and particle volumes fraction (PVF) were studied. It was found that there is significant stress concentration around the nanoparticles. The existence of nanoparticle will influence the stress wave propagation and thus the final stress and strain state of the material after LSP. In addition, particle size, PVF and particle orientation all influence the strain rate, static residual stress, static plastic strain and energy absorption during the LSP process.

A Volume-of-Fluid Based Numerical Simulation of Solidification in Binary Alloys on Fixed Non-Uniform Co-Located Grids

In this paper, the authors present a platform for the modeling of mold filling and solidification of binary alloys with properties similar to Mg alloys. A volume-of-fluid (VOF) based method is used to capture the interface between solid and liquid in binary alloys solidification process on a fixed non-uniform grid, developed for implementation in a colocated finite volume framework. Contrary to other works, to update the volume fraction (of fluid) in the field, a link between source-based type of energy equation and VOF reconstruction algorithm is described and implemented. A new approximation to the pressure gradient is presented to remove all ‘Spurious Currents’ [1] resulting from pressure jumps in the vicinity of the interface. Based upon the work presented, it is concluded that the present combination of the equations are not only computationally straightforward to implement and upgrade to a 3D problem, but also provides an excellent platform to capture the interface between constituents in a die-casting process including solidification and mold filling process. The current framework will be used in future works to characterize the local mechanical properties of Mg alloys by using information from simulation at the dendritic level.

Noise Reduction During Acoustic Monitoring of Laser Welding of High-Strength Steels

During the laser welding process of high-strength steels, different defects, such as a partial weld penetration, spatters, and blow-through holes could be present. In order to detect the presence of defects and achieve a quality control, acoustic monitoring based on microphones is applied to the welding process. As an effective sensor to monitor the laser welding process, however, the microphone is greatly limited by intensive noise existing in the complex industrial environment. In this paper, in order to acquire a clean acoustic signal from the laser welding process, two noise reduction methods are proposed: one is the spectral subtraction method based on one microphone and the other one is the beamforming based on a microphone array. By applying these two noise reduction methods, the quality of the acoustic signal is enhanced, and the acoustic signatures are extracted both in the time domain and frequency domain. The analysis results show that the extracted acoustic signatures can well indicate the different weld penetration states and they can also be used to study the internal mechanisms of the laser-material interaction.

Evaluation of Cooling Potential and Tool Life in Turning Using Metalworking Fluids Delivered in Supercritical Carbon Dioxide

Carbon Dioxide is an industrial byproduct that has been proposed as an alternative metalworking fluid (MWF) carrier with lower environmental impacts and better cooling potential than existing MWFs. This paper investigates the heat removal and tool life effects of rapidly expanding supercritical CO2 (scCO2)-based MWFs relative to MWFs delivered as a flood of semi-synthetic emulsion or as minimum quantity lubrication (MQL) sprays. When cutting both compacted graphite iron (CGI) and titanium, tool wear was most effectively controlled using the scCO2-based MWF compared with the other MWFs. Analysis in this paper suggests that the performance benefit imparted by rapidly expanding scCO2 appears to be related to both the cooling potential and penetration of the sprays into the cutting zone. High-pressure gas sprays have lower viscosity and higher velocity than conventional MWFs. An experiment in which the spray direction was varied clearly demonstrated the importance of spray penetration in tool wear suppression. The type of gas spray is also a significant factor in tool wear suppression. For instance, a spray of N2 delivered under similar conditions to CO2 effectively reduced tool wear relative to water based fluids, but not as much as CO2. This result is particularly relevant for MQL sprays which are shown to not cool nearly as effectively as scCO2 MWFs. These results inform development of scCO2-based MWFs in other machining operations, and provide insight into the optimization of scCO2 MWF delivery.

Cutting Simulation of Laser Assisted Milling of Silicon Nitride Ceramics Using PFC2D

Since laser assisted milling (LAMill) exhibits complicated characteristics in ceramic machining, this paper applies a distinct-element code, PFC2D (Particle Flow Code in Two-Dimensions), to conduct cutting simulation of laser assisted slab milling and explore its machining mechanism. The microstructure of a β-type silicon nitride ceramic (β-Si3N4) is modeled at grain scale. Clusters are used to simulate the rod-like grains of β-Si3N4. Parallel bonds are employed to represent the connection between intergranular glass phase and grains. A temperature-dependent PFC specimen is created for simulation of LAMill. A special milling cutter is designed for improving the computing efficiency. Simulation results show that the cutting force is strongly related to crack formation and propagation. The specific cutting energy decreases as the cutting temperature increases.

Algal Cell-Surface Interaction: An Overview and Preliminary Test

Five methods, namely adsorption, covalent binding, encapsulation, entrapment, and cross-linking, for algae immobilization were briefly reviewed in this article. The immobilization capabilities of four solid carrier materials (polystyrene, polyurethane, polyethylene, and cross-linked polyethylene) with two algal species (Nannochloropsis oculata and Scendesmus dimorphus) were tested. After 14 days of immobilization, polystyrene foam showed the best cell attachment and was covered by algae cells not only on the outer surface but also inside the porous spaces of the carrier. The cross-linked polyethylene also showed good attachment and growth of algae cells. Between the two algae species, N. oculata showed better cell attachment than S. dimorphus on all four materials indicating that cell characteristics played an important role in cell-surface interactions. The Derjaguin & Landau and Verwey & Overbeek (DLVO) theory was applied to understand the interaction mechanism and predicted attachment trends were found qualitatively accurate in matching the experimental results.

Dead Time Compensation for a Novel Positioning System via Predictive Controls and Virtual Intermittent Setpoints

Predictive control and intermittent setpoints are proposed to overcome the dead time that problem occurs in a new class of high precision position sensor for manufacturing equipment. In place of a rotary encoder or linear glass scale, a combination of a digital camera and a Liquid Crystal Display (LCD) screen is used to actively monitor two dimensional position changes on an XY table. In order to achieve precise spatial resolution, an actively-controlled planar pixel matrix is used as the tracking target for the system. A digital camera senses the location of the moving image displayed on the LCD screen and provides 2 dimensional position feedback. Thus, the timing and the quality of the visual feedback to the controller are the significant factors to determine the accuracy of the system. Due to the long image processing time, the vision feedback of the actual position of the stage is delayed. At the same time, with the slow frame capturing rates of the camera, dead time occurs between consecutive acquisitions of feedback signals from the vision system to the motion controller, which is detrimental to the performance of the system. Hence, studies and detailed analysis on different dead time compensation strategies and path planning algorithms have been performed to select the optimal strategy to address these challenges. Based on simulation results, a proposed method for integrating predictive control with virtual intermittent setpoints algorithm to mitigate dead time problem is presented in the final section of the paper.

Automatic Characterization of the Material Removal Rate in Laser Manufacturing of TiAl6V4 and Inconel 718

In this paper a system for the automatic determination of the material removal rate during laser milling process is presented. “Laser milling” can be defined as an engraving process with a strictly controlled penetration depth. In industrial applications, when a new material have to be machined or a change in the system set-up occur the user has to perform a time-consuming experimental campaign in order to determine the correlation between the material removal rate and the process parameters. In these cases the numerical models present some limits due to the elevated calculation time requested to simulate the laser milling of industrial features. In the proposed system, based on a regression model approach, the empirical coefficients, that provide the material removal rate, are automatically generated by a specific software according to the different materials that have to be processed. A description of the automated method and the results obtained in engraving TiAl6V4 and Inconel 718 superalloy with a fiber laser are presented. The system can be adapted to every combination of material/laser source.

Modeling and Simulation of Process and Structure Interactions Considering Turning Operations

A consideration of the dynamic interaction between the machine tool structure and the cutting process is required for the prediction and optimization of machining tasks through simulation. This paper outlines a modular, analytical cutting force model applicable to common turning processes. It takes into account the dynamic material behavior and nonlinear friction ratios on the rake face as well as heat transfer phenomena in the deformation zones. In order to overcome simplifying assumptions in analytical cutting force descriptions and to incorporate the chip formation process into the analysis, specific input variables are determined in a metal cutting simulation based on the Finite Element Method (FEM). On the machine tool structure side, the setup of a parametric FEM model is presented. The accuracy of both the machine tool and cutting force models was verified experimentally on a turning center.