Calibrating a composite material model for analysis and design of bamboo structures

This paper proposes a methodology to develop a material model for bamboo culms to use it in a more rigorous structural analysis and design. The study presented here is part of a broader research with the aim of exploiting the mechanical properties of bamboo in lightweight structures that may transfer predominantly axial compressive forces. The methodology is based on theoretical analysis and experimental tests. Composite material theory has been adopted to describe the mathematical model that can realistically reproduce the behaviour of bamboo culms. The composite material model is linear elastic and describes the axial and flexural stiffness, and the stress distribution across the culm wall thickness. For this study a series of experimental tests of the bamboo species Moso (Phyllostachys Pubescens) were devised to obtain the Modulus of Elasticity � under axial compressive loads. Establishing suitable test methods to determine material properties is not an easy task due to the difficulty of working with a non-isotropic and variable material. Experimental tests were based on two different codified methods (JG/T 199-2007; ISO 22157-2004) with the aim of reviewing the differences in the results of small coupons and full culm specimens, as well as emphasising the issues related to the measurement of strains in a material with through-thickness gradient fibre distribution under axial compression. In order to model the variability across the culm wall, the volume fraction of the fibres was calculated by image analysis. In addition, assessment of through-thickness strain distributions of small coupons using digital image correlation (DIC) was carried out and is discussed in this paper. The validation process for the composite material model is ongoing

T-violation in Kμ3K_{\mu3} decay in a general two-Higgs doublet model

We calculate the transverse muon polarization in the $K^+_{\mu3}$ process arising from the Yukawa couplings of charged Higgs boson in a general two-Higgs doublet model where spontaneous violation of CP is presentComment: 6 pages, latex, accepted for publication in Phys. Rev.

Digital analysis of the geometric variability of Guadua, Moso and Oldhamii bamboo

The implementation of sustainable building materials is currently one of the principal global challenges faced by the construction industry. Natural bamboo culms are a potential alternative to tackle this challenge due to its favourable environmental credentials as well as affordability. However, the organic geometry of bamboo culms is one of the barriers that prevents them from being implemented in formal design procedures. This work presents the details of a new digitisation workflow to systematically capture the geometry of bamboo culms through the application of 3D scanning technologies and reverse engineering principles. This workflow is applied to carry out a comprehensive analysis of the geometric variability of Guadua angustifolia kunth (Guadua), Phillostachys pubescens (Moso) and Bambusa oldhamii (Oldhamii) to identify potential correlation patterns. This geometric analysis showed a wide variation in the geometric properties of all species and no particular pattern was found which could be adopted for a potential visual grading system. These results highlight the challenges that the use of bamboo culms pose for the traditional design and fabrication processes developed for manufactured structural elements. The proposed reverse engineering methodology adopted for this study can be used to quantify and manage the geometric variability of bamboo culms to support the development of new formal design and fabrication processes for this natural structural element

Determination of the physical and mechanical properties of moso, guadua and oldhamii bamboo assisted by robotic fabrication

The large-scale urbanisation taking place in the developing world requires the construction industry to adopt alternative non-conventional renewable materials to reduce the unsustainable level of greenhouse gas emissions associated with the production of industrialised building materials. Bamboo is one of the most promising non-conventional building materials endemic to most developing countries, but there is still insufcient consistent information on the physical and mechanical properties of the numerous species suitable for construction. This study shows the potential of robotic fabrication to accelerate testing programmes on small clear samples of bamboo required to compare physical and mechanical properties across diferent species and difering plantation management practices. This fabrication method is applied on an experimental testing programme to determine the characteristic values of density, compressive strength, elastic modulus and shear strength of Phyllostachys pubescens (moso), Guadua angustifolia Kunth (guadua) and Guadua angustifolia (oldhamii). The efcient development of comprehensive experimental datasets of clear samples of bamboo is fundamental to inform the development of future design guidelines for bamboo as a construction material

Implementing TPM supported by 5S to improve the availability of an automotive production line

The maintenance management is a topic of strategic importance for automotive manufacturers. In fact, an effective maintenance process and a preventive maintenance (PM) procedure can significantly reduce the risk of equipment failures that can lead to downtime on the production lines. However, due to the complexity of an automotive production system, the risk of failure on a crucial piece of the production equipment cannot be entirely avoided. The study made in this paper aims at improving the availability of a critical production line through the total productive maintenance (TPM) methodology and supported by Lean Maintenance tools. An analysis is made of the initial condition of the line where the main problems are identified by employing several tools for this purpose, such as Mean Time between Failures (MTBF), Mean Time to Repair (MTTR), Overall Equipment Efficiency (OEE) and Availability (A). In response to the identified problems, an action plan is developed and implemented in order to find the root cause of the high number of malfunctions and faults in one of the line’s equipment with the use of 5S tools, visual management, and maintenance progress, as well as the development of a training program to increase operators’ skills. The results of such actions were positive as the line became more organized, the value of the MTBF increased, the MTTR value decreased, and consequently the overall availability increased.info:eu-repo/semantics/publishedVersio

Additive manufacturing: exploring the social changes and impacts

Despite the myriad of possibilities and applications of additive manufacturing (AM) technology, knowledge about the social impacts of this technology is very scarce and very limited in some areas. This paper explores how factors generated by the development of AM technology may create social impacts, affecting the health and social well-being of people, quality of life, working conditions, and the creation of wealth. This paper presents the results of an exploratory multiple case study conducted among four Portuguese organizations that use AM technology, aiming to determine their perceptions regarding the social impacts of AM, its effects, and causes. The results confirm that AM technology is mainly seen to create positive impacts on health and safety (regarding physical hazards), on expectations for the future, on leisure and recreation, on low disruption with the local economy, on economic prosperity, on the professional status, and on innovative employment types. Nevertheless, a negative impact was also found on health and safety (concerning hazardous substances), as well as several mixed and null impacts. The main limitations of the research arise from the use of a case study methodology, since the results can be influenced by contextual factors, such as the size of the organizations in the sample, and/or social, cultural, technological, political, economic, and ecological factors. This study gives an up-to-date contribution to the topic of AM social impacts and social changes, an area which is still little-explored in the literature.info:eu-repo/semantics/publishedVersio

Power Series Solution for Solving Nonlinear Burgers-Type Equations

Power series solution method has been traditionally used to solve ordinary and partial linear differential equations. However, despite their usefulness the application of this method has been limited to this particular kind of equations. In this work we use the method of power series to solve nonlinear partial differential equations. The method is applied to solve three versions of nonlinear time-dependent Burgers-type differential equations in order to demonstrate its scope and applicability

Influence of textile cord tension in cap ply production

The deep knowledge about manufacturing processes, as well as their optimization, present themselves as indispensable factors in the search for the best product quality. It is this point of view of continuous improvement that makes companies in profitable and sustainable way. This paper presents a study about unwinding tension of textile cords in the cap ply manufacturing process, using machines called cap-strips for production. In this work, tension can be understood as the tensile force exerted on the cord. This study determines the influence of unwinding tension on the physical and shrinkage properties of the cord, as well as on the properties of cap ply, namely green adhesion and peel adhesion. Furthermore, the impact of cord tension on tire uniformity and the manufacturing process itself was also studied. All conclusions are based on the performed experiments and the execution of statistical tests. This work allows to conclude that the unwinding tension of the textile cords have some impact on the cap ply properties but have no influence on the tire uniformity.info:eu-repo/semantics/publishedVersio

Development of a suitable project management approach for projects with parallel planning and execution

30th International Conference on Flexible Automation and Intelligent Manufacturing (FAIM2021) -15-18 June 2021, Athens, GreeceIn a big company, project management (PM) is always present. Traditional predictive PM approach is concerned with planning everything in advance and then controlling and adjusting if necessary, throughout the project timeline. This may work well when the requirements are well established, but for maintenance projects brings inherent uncertainty. When the subject is aircraft maintenance, it is almost impossible to plan everything at the beginning and expect that it will occur as planned because however a scheduled maintenance plan exists, according to statistics 60% of the aircraft total failure can only be found with ground inspection which means, that even if a plan is established before receiving the aircraft, it will most certainly need to be significantly changed. This requires a big effort from the planning team to plan everything right and ensure that all tools and resources are available to perform the required tasks. To solve this issue, in this paper we propose a hybrid project management approach developed to a case study company from the aircraft repair sector, to enable a faster planning while taking into account the priorities and dependencies of the inherent project tasks with the available resources.The authors would like to acknowledge financial support from Fundação para a Ciência e Tecnologia (Grants: UID/EMS/00667/2019 and UID/UIDB/CPO/04058/2020).info:eu-repo/semantics/publishedVersio