On the compact wave dynamics of tensegrity beams in multiple dimensions

This work presents a numerical investigation on the nonlinear wave dynamics of tensegrity beams in 1D, 2D and 3D arrangements. The simulation of impact loading on a chain of tensegrity prisms and lumped masses allows us to apply on a smaller scale recent results on the propagation of compression solitary waves in 1D tensegrity metamaterials. Novel results on the wave dynamics of 2D and 3D beams reveal - for the first time - the presence of compact compression waves in two- and three-dimensional tensegrity lattices with slender aspect ratio. The dynamics of such systems is characterized by the thermalization of the lattice nearby the impacted regions of the boundary. The portion of the absorbed energy moving along the longitudinal direction is transported by compression waves with compact support. Such waves emerge with nearly constant speed, and slight modifications of their spatial shape and amplitude, after collisions with compression waves traveling in opposite direction. The analyzed behaviors suggest the use of multidimensional tensegrity lattices for the design and additive manufacturing of novel sound focusing devices

Control Parameters and Materials Selection Criteria for Rapid Prototyping Systems

Since the introduction ofrapid prototyping technology as a tool for time compression and concurrent engineering in the design and manufacturing process, many enhancements and refinements have been made based on the experience ofusers and manufacturers ofrapid prototyping equipment. These improvements contribute significantly to faster production of quality output from rapid prototyping systems. There are diverse control and material selection parameters that affect prototype models built using the Fused Deposition Modeling (FDM®) process. This paper reviews the role of several ofthese parameters in the process. Data will be presented to help the user choose the appropriate material for specific applications including density, tensile stiffhess, flexural stiffhess, tensile strength, flexural strength, tensile ductility, shock resistance, and hardness.Mechanical Engineerin

Manufacturing Processing and Properties Manipulations of Thick Advanced Performance PEEK Polymer and Composites for Biomedical and Extremely Harsh Environments

This study’s aim is to investigate manipulating the compression molding manufacturing process to influence morphology and mechanical properties of thick wall and tall advanced performance thermoplastic polymers, as well as to highlight the mechanisms that cause property deterioration in those products. Two advanced performance polymer systems, neat poly(etheretherketone) (PEEK) and its composite (CF/PEEK), were considered as model systems to fundamentally understand structure-property relationships in thick wall advanced polymeric materials. An instrumented compression molding setting with thermal control and 3D embedded thermocouples is designed and fabricated to produce thick polymer parts and investigate how altering processing procedures influences properties. A novel hybrid sealing method is invented to enhance compression molding quality and avoid leaking issues associated with this process. The temperature distribution profiles throughout the compression molding and the bushing are collected during heating and cooling processes. The resultant temperature profiles are analyzed to further understand the compression molding process behavior, and thus adjust the processing procedure to enhance products morphology and properties. Crystal structure formation is controlled via templating material manufacturing cooling process. The influence of holding temperature at the crystallization temperature while increasing the hold time is examined by characterizing samples throughout bushings processed using various strategies. Manipulating the cooling is expected to guide the polymer amorphous arrangement toward a uniform crystal structure and grow this structure equivalently throughout the thick cross-section and the extended length of the final product. Remarkable crystallinity improvement with adequate consistency was achieved throughout thick wall and tall compression molded PEEK bushing that improved the compression molding product properties. Carbon fiber reinforcement’s influence on crystal morphology and mechanical properties of thick products is addressed in this dissertation. Different techniques and tests are used to investigate the bushings produced using different processing strategies such as dynamic scanning calorimetry (DSC), dynamic mechanical analysis (DMA), scanning electron microscopy (SEM), wide angle x-ray scattering (WAXS), polarized optical microscopy (POM), compression test, and 3-point bending test. Those techniques assisted in establishing correlation between the morphology modification and the material properties response. Predictive numerical models are developed to simulate the compression molding heating process. Experimental validations provide beneficial tools to predict the heating time required for various thick compression molded materials. The predictive models established in this study can substitute building an expensive thermal control system and performing compression molding with embedded thermocouples to estimate material processing time. These models can provide a great assist for industrial applications. This study highlights an intelligible processing procedure for developing thick compression molding bushing with consistent crystallinity and enhanced mechanical properties. The processing protocol introduced in this study acquired based on analyzing compression molding temperature profiles and studying the possibility of using different methods to control the process during the cooling stage to produce neat and composite polymers with better properties. The produced products can be used for many applications such as aerospace, biomedical, automotive, food processing, oil and gas industry, etc

Achieving High Excipient Efficiency with Elastic Thermoplastic Polyurethane by Ultrasound Assisted Direct Compression

Ultrasound assisted compression (USAC) is a manufacturing technique which applies thermal and mechanical energy to the powder bed, producing tablets with improved characteristics compared to the direct compression process. This technology is ideal for thermoplastic materials, as polyurethanes, whose particles usually undergo a sintering process. Thermoplastic polyurethanes are widely used in sustained drug release systems but rarely seen in tablets due to their elastic properties. The aim of this work is to investigate the ability of USAC to manufacture sustained release matrix tablets based on elastic thermoplastic polyurethanes (TPU), overcoming the limitations of direct compression. The technological and biopharmaceutical characteristics of the TPU matrices have been evaluated, with special focus on the porous structure due to the implications on drug release. For the first time, USAC has been successfully employed for manufacturing elastic thermoplastic polyurethanes-based matrices. TPU tablets show an inert character with a sustained drug release governed by a diffusional mechanism. Initial porosity of matrices was similar in all batches studied, with no influence of drug particle size, and a fractal nature of the pore network has been observed. SEM microphotographs show the continuum medium created by the sintering of the polymer, responsible for the high excipient efficiency.España, Ministerio de Economía y Competitividad Grant MAT2016- 77345-C3-3-PEspaña, Junta de Andalucía Grant 2017/0000043

Reliability Assessment of a Packaging Automatic Machine by Accelerated Life Testing Approach

Industrial competitiveness in innovation, the time of the market introduction of new machines and the level of reliability requested implies that the strategies for the development of products must be more and more efficient. In particular, researchers and practitioners are looking for methods to evaluate the reliability, as cheap as possible, knowing that systems are more and more reliable. This paper presents a reliability assessment procedure applied to a mechanical component of an automatic machine for packaging using the accelerated test approach. The general log-linear (GLL) model is combined based on a relationship between a number strains, in particular mechanical and time based. The complete Accelerated Life Testing - ALT approach is presented by using Weibull distribution and Maximum Likelihood verifying method. A test plan is proposed to estimate the unknown parameters of accelerated life models. Using the proposed ALT model, the reliability function of the component is evaluated and then compared with data from the field collected by customers referring to 8 years of real work on a fleet of automatic packaging machines. The results confirm that the assessment method through ALT is effective for lifetime prediction with shorter test times, and for the same reason it can improve the design process of automatic packaging machines

Adoption of integrated cattle and oil palm farming system in Malaysia

Malaysian government had encouraged the adoption of integrated cattle and oil palm farming system (ICOFS) since the year 1998. This is due to large areas of land suitable for ICOFS in Malaysia that can be well utilised. Rising up the participation in ICOFS is one of the effort in facing the increasing demand of meat nationwide and growing dependency on imported meat. Apart from that, Malaysia needs to increase the self�sufficiency level of national meat production to 32.7% by 2020 as stated in the National Agri-Food Policy 2011-2020. Despite this, only a small number of farmers have adopted ICOFS in Malaysia and less is known so far about the farmer's attitudes towards the ICOFS in Malaysia. Therefore, this study aimed to explore the current practice as well as factors affecting and constraints to the adoption of ICOFS in Malaysia. Interviews of four selected experts in ICOFS were held to examine the current practice of ICOFS in Malaysia. Results from the interviews and literature review have been cross-compared to develop questionnaire instruments. Then, the survey questionnaire was carried out to 153 adopters and non-adopters of ICOFS in Johor, Malaysia to identify the key factors that influence the adoption of ICOFS. The study found that information and know-how and availability of skilled labour are the significant factors that encourage farmers to adopt ICOFS. On the other hand, government support and policy constraint and production and on-farm constraint are the significant constraints hindering the adoption of ICOFS. Based on the findings of this study, one of the measure to increase the rate of adoption of ICOFS are by helping the farmers to hire extra labour and to have skills needed. Furthermore, rate of ICOFS could also be increase by helping the farmers to have better control on weed, pest and diseases on farm as well as not interrupting their oil palm production. In addition, it is suggested to provide them with more opportunity towards incentives, training and technical support from the field officers. It is suggested for future research to explore the effect of factors affecting adoption and constraints to adoption on other attitudinal and psychological outcomes such as satisfaction, successfulness, involvement and degree of use

Deployment verification of large CFRP helical high-gain antenna for AIS signals

Deployment verification of large CFRP helical high-gain antenna for AIS signal

Material Issues of the Metal Printing Process, MPP

The metal printing process, MPP; is a novel Rapid Manufacturing process under development at SINTEF and NTNU in Trondheim, Norway. The process, which aims at the manufacturing of end-use products for demanding applications in metallic and CerMet materials, consists of two separate parts; The layer fabrication, based on electrostatic attraction of powder materials, and the consolidation, consisting of the compression and sintering of each layer in a heated die. This approach leads to a number of issues regarding the interaction between the process solutions and the materials. This paper addresses some of the most critical material issues at the current development stage of MPP, and the present solutions to these.Mechanical Engineerin

Continuous direct compression as manufacturing platform for sustained release tablets

This study presents a framework for process and product development on a continuous direct compression manufacturing platform. A challenging sustained release formulation with high content of a poorly flowing low density drug was selected. Two HPMC grades were evaluated as matrix former: standard Methocel CR and directly compressible Methocel DC2. The feeding behavior of each formulation component was investigated by deriving feed factor profiles. The maximum feed factor was used to estimate the drive command and depended strongly upon the density of the material. Furthermore, the shape of the feed factor profile allowed definition of a customized refill regime for each material. Inline NIRs was used to estimate the residence time distribution (RTD) in the mixer and monitor blend uniformity. Tablet content and weight variability were determined as additional measures of mixing performance. For Methocel CR, the best axial mixing (i.e. feeder fluctuation dampening) was achieved when an impeller with high number of radial mixing blades operated at low speed. However, the variability in tablet weight and content uniformity deteriorated under this condition. One can therefore conclude that balancing axial mixing with tablet quality is critical for Methocel CR. However, reformulating with the direct compressible Methocel DC2 as matrix former improved tablet quality vastly. Furthermore, both process and product were significantly more robust to changes in process and design variables. This observation underpins the importance of flowability during continuous blending and die-filling. At the compaction stage, blends with Methocel CR showed better tabletability driven by a higher compressibility as the smaller CR particles have a higher bonding area. However, tablets of similar strength were achieved using Methocel DC2 by targeting equal porosity. Compaction pressure impacted tablet properties and dissolution. Hence controlling thickness during continuous manufacturing of sustained release tablets was crucial to ensure reproducible dissolution. (C) 2017 Elsevier B.V. All rights reserved

Making automation pay - cost & throughput trade-offs in the manufacture of large composite components

The automation of complex manufacturing operations can provide significant savings over manual processes, and there remains much scope for increasing automation in the production of large scale structural composites. However the relationships between driving variables are complex, and the achievable throughput rate and corresponding cost for a given design are often not apparent. The deposition rate, number of machines required and unit production rates needed are interrelated and consequently the optimum unit cost is difficult to predict. A detailed study of the costs involved for a series of composite wing cover panels with different manufacturing requirements was undertaken. Panels were sized to account for manufacturing requirements and structural load requirements allowing both manual and automated lay-up procedures to influence design. It was discovered that the introduction of automated tape lay-up can significantly reduce material unit cost, and improve material utilisation, however higher production rates are needed to see this benefit