Jorge Ramos, Patrícia Pinto, Pedro Pintassilgo, Anabela Resende and Luís Cancela da Fonseca
There is an increasing interest in visiting protected areas in the Algarve (Portugal). Tourists are interested in contact with nature activities. However, protected areas are…
Abstract
Purpose
There is an increasing interest in visiting protected areas in the Algarve (Portugal). Tourists are interested in contact with nature activities. However, protected areas are quite sensitive to human pressure and are limited in their carrying capacity. The purpose of this study is to fill a literature gap concerning which features attract tourists who visit saltpans via a pedestrian tour and what sort of pressure they inflict on waterbirds’ behaviour.
Design/methodology/approach
The tour consists of a predefined path with interpretive boards and guides who provide explanations to visitors. This study is threefold: to find out if waterbirds are disturbed by the presence of tourists, if tourists prefer to learn more about saltpans instead of finding waterbirds and if tourists have any preferred waterbird species. The methods used are direct observations with binoculars of the saltpan area and a short questionnaire. With the data collected, three hypotheses are tested.
Findings
The results show that the occurrence of waterbirds does not vary according to the presence or absence of tourist visits, tourists prefer visiting saltpans rather than watching waterbirds and there is some waterbird species preference.
Practical implications
Few people can visit the saltpan while keeping disturbance of both waterbirds and workers to a minimum. This study gives insights into sustainable ecotourism practices and how to articulate them with saltpan works.
Originality/value
The value of this study can be demonstrated by the interconnection between traditional salt production, waterbirds’ habitat, visitors’ interest and their interaction.
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Gonzalo Reyes Donoso, Magdalena Walczak, Esteban Ramos Moore and Jorge Andres Ramos-Grez
The purpose of this paper is to explore the possibility of producing Cu-based shape memory alloys (SMA) by means of direct metal laser fabrication (DMLF).
Abstract
Purpose
The purpose of this paper is to explore the possibility of producing Cu-based shape memory alloys (SMA) by means of direct metal laser fabrication (DMLF).
Design/methodology/approach
The fabrication approach consists of the combination of laser melting of a metallic powder with heating treatment in a controlled inert atmosphere. Three prospective Cu-Al-Ni alloy compositions were tested, and the effects of laser power, as well as laser exposure time, were verified.
Findings
All the processed materials were found to attain microstructures and phase change transformation temperatures typical of this type of SMA.
Practical implications
Further development of this technique will allow for fabrication of large elements with considerable shape memory effect, which are currently not viable due to high cost of nitinol.
Originality/value
This work showed a proof of concept toward the development of DMLF-based additive manufacturing of near net shape components of Cu-based SMAs from elemental powders.
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Iván La Fé-Perdomo, Jorge Andres Ramos-Grez, Ramón Quiza, Ignacio Jeria and Carolina Guerra
316 L stainless steel alloy is potentially the most used material in the selective laser melting (SLM) process because of its versatility and broad fields of applications (e.g…
Abstract
Purpose
316 L stainless steel alloy is potentially the most used material in the selective laser melting (SLM) process because of its versatility and broad fields of applications (e.g. medical devices, tooling, automotive, etc.). That is why producing fully functional parts through optimal printing configuration is still a key issue to be addressed. This paper aims to present an entirely new framework for simultaneously reducing surface roughness (SR) while increasing the material processing rate in the SLM process of 316L stainless steel, keeping fundamental mechanical properties within their allowable range.
Design/methodology/approach
Considering the nonlinear relationship between the printing parameters and features analyzed in the entire experimental space, machine learning and statistical modeling methods were defined to describe the behavior of the selected variables in the as-built conditions. First, the Box–Behnken design was adopted and corresponding experimental planning was conducted to measure the required variables. Second, the relationship between the laser power, scanning speed, hatch distance, layer thickness and selected responses was modeled using empirical methods. Subsequently, three heuristic algorithms (nonsorting genetic algorithm, multi-objective particle swarm optimization and cross-entropy method) were used and compared to search for the Pareto solutions of the formulated multi-objective problem.
Findings
A minimum SR value of approximately 12.83 μm and a maximum material processing rate of 2.35 mm3/s were achieved. Finally, some verification experiments recommended by the decision-making system implemented strongly confirmed the reliability of the proposed optimization methodology by providing the ultimate part qualities and their mechanical properties nearly identical to those defined in the literature, with only approximately 10% of error at the maximum.
Originality/value
To the best of the authors’ knowledge, this is the first study dealing with an entirely different and more comprehensive approach for optimizing the 316 L SLM process, embedding it in a unique framework of mechanical and surface properties and material processing rate.
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Germán Omar Barrionuevo, Jorge Andrés Ramos-Grez, Magdalena Walczak, Xavier Sánchez-Sánchez, Carolina Guerra, Alexis Debut and Edison Haro
The effect of processing parameters on the microstructure of steel produced by laser-based powder bed fusion (LPBF) is a recognized opportunity for property design through…
Abstract
Purpose
The effect of processing parameters on the microstructure of steel produced by laser-based powder bed fusion (LPBF) is a recognized opportunity for property design through microstructure control. Because the LPBF generates a textured microstructure associated with high anisotropy, it is of interest to determine the fabrication plane that would generate the desired property distribution within a component.
Design/methodology/approach
The microstructure of 316 L produced by LPBF was characterized experimentally (optical, scanning electron microscopy, glow discharge emission spectrometry and X-ray diffraction), and a finite element method was used to study the microstructure features of grain diameter, grain orientation and thermal parameters of cooling rate, thermal gradient and molten pool dimensions.
Findings
The computational tool of Ansys Additive was found efficient in reproducing the experimental effect of varying laser power, scanning speed and hatch spacing on the microstructure. In particular, the conditions for obtaining maximum densification and minimum fusion defects were consistent with the experiment, and the features of higher microhardness near the component’s surface and distribution of surface roughness were also reproduced.
Originality/value
To the best of the author’s knowledge, this paper is believed to be the first systematic attempt to use Ansys Additive to investigate the anisotropy of the 316 L SS produced by LPBF.
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Iván La Fé-Perdomo, Jorge Andres Ramos-Grez, Gerardo Beruvides and Rafael Alberto Mujica
The purpose of this paper is to outline some key aspects such as material systems used, phenomenological and statistical process modeling, techniques applied to monitor the…
Abstract
Purpose
The purpose of this paper is to outline some key aspects such as material systems used, phenomenological and statistical process modeling, techniques applied to monitor the process and optimization approaches reported. All these need to be taken into account for the ongoing development of the SLM technique, particularly in health care applications. The outcomes from this review allow not only to summarize the main features of the process but also to collect a considerable amount of investigation effort so far achieved by the researcher community.
Design/methodology/approach
This paper reviews four significant areas of the selective laser melting (SLM) process of metallic systems within the scope of medical devices as follows: established and novel materials used, process modeling, process tracking and quality evaluation, and finally, the attempts for optimizing some process features such as surface roughness, porosity and mechanical properties. All the consulted literature has been highly detailed and discussed to understand the current and existing research gaps.
Findings
With this review, there is a prevailing need for further investigation on copper alloys, particularly when conformal cooling, antibacterial and antiviral properties are sought after. Moreover, artificial intelligence techniques for modeling and optimizing the SLM process parameters are still at a poor application level in this field. Furthermore, plenty of research work needs to be done to improve the existent online monitoring techniques.
Research limitations/implications
This review is limited only to the materials, models, monitoring methods, and optimization approaches reported on the SLM process for metallic systems, particularly those found in the health care arena.
Practical implications
SLM is a widely used metal additive manufacturing process due to the possibility of elaborating complex and customized tridimensional parts or components. It is corroborated that SLM produces minimal amounts of waste and enables optimal designs that allow considerable environmental advantages and promotes sustainability.
Social implications
The key perspectives about the applications of novel materials in the field of medicine are proposed.
Originality/value
The investigations about SLM contain an increasing amount of knowledge, motivated by the growing interest of the scientific community in this relatively young manufacturing process. This study can be seen as a compilation of relevant researches and findings in the field of the metal printing process.
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Guillermo Zañartu‐Apara and Jorge Ramos‐Grez
The purpose of this paper is to study the effect of different parameters (layer thickness, jetted binder volume per layer and type of binder and temperature) on the mechanical…
Abstract
Purpose
The purpose of this paper is to study the effect of different parameters (layer thickness, jetted binder volume per layer and type of binder and temperature) on the mechanical properties of parts made with an experimental 3D printing (3DP) process. This 3DP device built for this project is based on the spiral growth manufacturing (SGM) device previously introduced by Hauser et al. at The University of Liverpool. It differs from the common 3DP in that it generates the different parts using only one rotating piston instead of two non‐rotating ones.
Design/methodology/approach
Several parts are produced using this device according to an experimental design, repeating each run three times. The experimental machine is able to make every part needed without major issues, demonstrating that it is possible to build a functional device using common and standard components.
Findings
Experimental analysis of the printed parts shows that the layer thickness has the highest effect on apparent density, hardness and fracture strength of the parts made.
Originality/value
Empirical information is provided about mechanical behavior (e.g. apparent density, hardness and fracture strength) of parts made under different processing factors (e.g. binder type, layer thickness, quantity of binder and chamber temperature) using a SGM‐based 3DP experimental device.
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Cristobal Arrieta, Sergio Uribe, Jorge Ramos‐Grez, Alex Vargas, Pablo Irarrazaval, Vicente Parot and Cristian Tejos
In medical applications, it is crucial to evaluate the geometric accuracy of rapid prototyping (RP) models. Current research on evaluating geometric accuracy has focused on…
Abstract
Purpose
In medical applications, it is crucial to evaluate the geometric accuracy of rapid prototyping (RP) models. Current research on evaluating geometric accuracy has focused on identifying two or more specific anatomical landmarks on the original structure and the RP model, and comparing their corresponding linear distances. Such kind of accuracy metrics is ambiguous and may induce misrepresentations of the actual errors. The purpose of this paper is to propose an alternative method and metrics to measure the accuracy of RP models.
Design/methodology/approach
The authors propose an accuracy metric composed of two different approaches: a global accuracy evaluation using volumetric intersection indexes calculated over segmented Computed Tomography scans of the original object and the RP model. Second, a local error metric that is computed from the surfaces of the original object and the RP model. This local error is rendered in a 3D surface using a color code, that allow differentiating regions where the model is overestimated, underestimated, or correctly estimated. Global and local error measurements are performed after rigid body registration, segmentation and triangulation.
Findings
The results show that the method can be applied to different objects without any modification, and provide simple, meaningful and precise quantitative indexes to measure the geometric accuracy of RP models.
Originality/value
The paper presents a new approach to characterize the geometric errors in RP models using global indexes and a local surface distribution of the errors. It requires minimum human intervention and it can be applied without any modification to any kind of object.
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Antonio Amado‐Becker, Jorge Ramos‐Grez, María José Yañez, Yolanda Vargas and Luis Gaete
The purpose of this paper is to present results of an investigation, where the elastic tensor based on the engineering constants of sinterized Nylon 12 is characterized and is…
Abstract
Purpose
The purpose of this paper is to present results of an investigation, where the elastic tensor based on the engineering constants of sinterized Nylon 12 is characterized and is modeled considering a transversely isotropic behavior as a function of apparent density (relative mass density).
Design/methodology/approach
The ultrasound propagation velocity measurement through the material in specific directions by means of the pulse transmission method was used, relating the elastic tensor elements to the phase velocity magnitude through Christoffel's equation. In addition conventional uniaxial tensile tests were carried out to validate the used technique. Laser sintering of Nylon 12 powder (Duraform PA) has been performed at different laser energy densities, fabricating cube‐shaped coupons as well as dogbone flat coupons, using an SLS 125 former DTM machine.
Findings
Correlations for each one of the Young moduli, Shear constants and Poisson's ratios, presenting an exponential behavior as a function of the sintering degree, were generated. In addition, as the apparent density reaches a maximum value of 977 kg/m3 at an energy density of 0.032 J/mm2, the material behaves in an almost isotropic form, presenting average values for the Young modulus, Shear modulus and Poisson's ratio corresponding to 2,310 MPa, 803 MPa and 0.408, respectively.
Research limitations/implications
The research is limited only to one type of material within the elastic range. Validation of the Young modulus measured along one direction only is performed using a tensile test machine, due to the difficulties in evaluating Poisson's ratios and Shear moduli using conventional tests.
Practical implications
The results presented can be applied to virtual design and evaluating processes such as finite element analysis.
Originality/value
The paper incorporates detailed information regarding the complete elastic characteristics of Nylon 12, including additional measurements of the Shear moduli and Poisson's ratios not studied previously.
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Keywords
Kriti Dhingra and Kanika Dhingra Sardana
Introduction: Sustainability and Industry 4.0 have recently influenced the global economy. With the Industrial Revolution 4.0, there has been a significant focus on digital…
Abstract
Introduction: Sustainability and Industry 4.0 have recently influenced the global economy. With the Industrial Revolution 4.0, there has been a significant focus on digital sustainability in enterprises. Micro, small and medium enterprises (MSMEs) are the most vulnerable sections regarding new transformations.
Purpose: Even during the COVID-19 pandemic, when all businesses had no option other than to adopt digitisation, MSMEs faced tremendous issues to make this shift. Despite the immense focus on digital sustainability, some deterrents exist to its adoption in MSMEs. Contemporary research focuses on determining the critical deterrents to digital sustainability in MSMEs.
Methodology: This chapter employs the interpretive structural modelling technique, and Matrice impacts Croises Multiplication Appliqué a classement (MICMAC) analysis to identify and further classify the deterrents to digital sustainability in MSMEs.
Findings: Legal barriers and firms’ economic conditions are identified as the major deterrents. Eliminating these deterrents would help minimise the minor ones too. To deliver global sustainability goals, digital sustainability must be duly adopted everywhere.