Mechanical Testing Of Samples Research Articles

Biodegradable polymer composites based on polylactide used in selected 3D technologies

As part of the work, new polymer materials were used in 3D printing, which can be used in three technologies depending on the apparatus used: Fused Filament Fabrication (FFF), Melted and Extruded Manufacturing (MEM), Melt Extrusion Polymers (MEP). As part of the work, the properties of obtained polymer composites were examined. Polylactide (PLA) was used as the matrix, and powdered natural ground fillers were used as fillers: bamboo dust (PB), cork dust (PK) and wood dust (PD). In the first part of the work, filaments were received from the tested composites using the filament preparation line made by METACHEM in Torun for use in 3D printers. Samples for mechanical tests were obtained from the filaments thus received by means of an MEP printer and after granulation by injection molding. In the next part of the work, rheological, mechanical and structural properties of obtained composites were examined. It was found that the addition of natural fillers increased the fluidity of the obtained polymeric materials in the case of composite with addition of PK even by 48.73% compared to unfilled PLA. It was also observed that the composites obtained had lower Charpy impact strength, Rockwell hardness and tensile strength. Observation of the microstructure of the composites using SEM confirmed the even distribution of natural fillers in the polymer matrix, which proves well-chosen parameters of their homogenization in the polymer matrix.

Fracture toughness of a metal\u2013organic framework glass

Metal-organic framework glasses feature unique thermal, structural, and chemical properties compared to traditional metallic, organic, and oxide glasses. So far, there is a lack of knowledge of their mechanical properties, especially toughness and strength, owing to the challenge in preparing large bulk glass samples for mechanical testing. However, a recently developed melting method enables fabrication of large bulk glass samples (>25 mm3) from zeolitic imidazolate frameworks. Here, fracture toughness (KIc) of a representative glass, namely ZIF-62 glass (Zn(C3H3N2)1.75(C7H5N2)0.25), is measured using single-edge precracked beam method and simulated using reactive molecular dynamics. KIc is determined to be ~0.1 MPa m0.5, which is even lower than that of brittle oxide glasses due to the preferential breakage of the weak coordinative bonds (Zn-N). The glass is found to exhibit an anomalous brittle-to-ductile transition behavior, considering its low fracture surface energy despite similar Poisson’s ratio to that of many ductile metallic and organic glasses.

Prediction of geometry deviations in additive manufactured parts: comparison of linear regression with machine learning algorithms

Dimensional accuracy in additive manufacturing (AM) is still an issue compared with the tolerances for injection molding. In order to make AM suitable for the medical, aerospace, and automotive industries, geometry variations should be controlled and managed with a tight tolerance range. In the previously published article, the authors used statistical analysis to develop linear models for the prediction of dimensional features of laser-sintered specimens. Two identical builds with the same material, process, and build parameters were produced, resulting in 434 samples for mechanical testing (ISO 527-2 1BA). The developed linear models had low accuracy, and therefore needed an application of more advanced data analysis techniques. In this work, machine learning techniques are applied for the same data, and results are compared with the previously reported linear models. The linear regression model is the best for width. Multilayer perceptron and gradient boost regressor models have outperformed other for thickness and length. The recommendations on how the developed models can be used in the future are proposed.

Mechanical Properties of Porous Ti-Nb-Zr Alloy Fabricated by Using a Combined Process of Decomposite - Sintering Method in Vacuum Atmosphere

Present research work reports a study on new mechanical phenomenon of the porous Ti-3.5Nb-3.5Zr materials that address for implant materials in dental. The mechanical testing samples were prepared by two-step sintering method with dimension of 10 mm and height of 10mm. The compressive tests were carried on MTS instrument to determine the strain-stress curves. Then mechanical behavior of the materials was analyzed from those curves. For samples after sintering without space holder and binder addition, there were three deformation regions on the curves that were linear elasticity, plateau and densification. The mechanical behavior of materials was modeled, and the main parameters in the model were identified from the strain - stress curve. For sample after sintering with space holder and binder, materials were brittle. The mechanical properties of those samples were also determined. Microstructures of materials before mechanical testing were observed by SEM, and the surface was also analyzed by XRD.

MECHANICAL TESTING AND NUMERICAL MODELLING OF POROUS STRUCTURES IMPROVING OSEINTEGRATION OF IMPLANTS

Implants, such as dental, are ordinary devices in medical care nowadays, even though they are quite expensive. In the present study, the use of trabecular and gyroid structures as external layer of implants is examined. The advantage of porous structures compared to surface modification of compact implants is the possibility to be fabricated by additive manufacturing together with the whole implant. The additive manufacturing also allows us to produce various shapes with controlled porosity for bone ingrowth. The design of 6 types of trabecular and 4 types of gyroid structures is part of the study. The trabecular structures are strut-based, whereas the gyroid structures are based on a wall system. The study is focused on mechanical testing of samples which were 3D printed from the titanium alloy Ti6Al4V. The gyroid structures, which we evaluated as more reliable, were chosen for numerical modelling. Other observed advantages and disadvantages of the structures are also discussed.

Some properties of plywood produced from 10 cultivars of poplar

ABSTRACTThe aim of this paper is to study the possible influence of poplar cultivar and soil on the mechanical properties of plywood produced from 10 cultivars having grown in different soils. For each cultivar, two trees were harvested per station; crosscut into bolts then peeled 1.4 mm thick for one tree and 3 mm thick for the other one: in total, 80 trees were sampled. The veneers were used to make 160 boards using 2 adhesives: polyvinyl acetate (PVAc) and melamine-urea-formaldehyde (MUF). These boards were then cut into standardized samples for non-destructive and destructive mechanical tests. The properties of plywood were characterized by measuring their density, modulus of elasticity and modulus of rupture. The results showed that poplar plywood properties could be influenced by adhesive and veneer thickness. The cultivar and soil effects were never relevant. A tight correlation was found between destructive and non-destructive modulus of elasticity tests.

Investigation of Low Rotational Speeds Effect during Centrifugal Casting on the Mechanical Properties of Polymer Composites Material

In this article, we present our developed and manufactured centrifugal casting machine. We present the results of mechanical testing of samples from polymer composites made on it. At the beginning we give an overview of the main trends in the market of polymer composites. We consider the main factors affecting the mechanical characteristics of polymer composites, and determine the main limitations of using centrifugal casting technology for polymer composites. In conclusion, we give directions for further research. Many industries use polymer composite materials (PMC) to meet production needs. The main advantage of PMC is the possibility of obtaining high strength with relatively low weight, as well as the possibility of obtaining additional necessary properties, such as dielectric, magnetic, etc. The PMC market continues to grow, and now PMC is widely used in aircraft manufacturing, automotive, medicine, etc. [1]. Despite the positive aspects of using PMC, this method has some drawbacks. Firstly, low automation of the process of casting parts from PMC. Many technologies are quite difficult to automate due to their process complexity and constant monitoring. Development in this direction is already underway, and there are practical solutions, such as automatic tape placement (ATL) / automatic fiber placement (AFP) [2]. On the other hand, the cost of these solutions is quite high. Secondly, the high cost of the equipment and tooling manufacturing. Such technologies as pressing, pressing and autoclave molding using prepregs are attached to certain technological equipment and need to organize pressure, maintain temperature, etc. This increases the range of equipment used and overall process complexity. In some technologies using high pressure and heat-cooling such as pressure casting (RTM) [3], it is necessary to use high-strength steels for molds, the processing of which takes a long time and wears the tool. Thirdly, increased knowledge-intensive work and high requirements for staff qualifications [4]. Manufacturing products from PMC requires careful monitoring by the technologist, since the influence of such parameters as: temperature, pressure will affect on the product structure and, accordingly, its characteristics. Fourthly, loss of strength after cutting operations (such as drilling, milling, taping and so on) and further stratification of PMC [5]. This leads us to the fact that used technology should maximally ensure the product geometry with minimization of subsequent post-processing.

Comparing mechanical properties of impact modified polypropylene-copolymer (IMPP) from injection molding (IM) and fused layer modeling (FLM) processes

Purpose The purpose of this study was to produce dimensionally accurate and reliable fused layer modeling (FLM) feedstock composed of an impact modified polypropylene matrix, compounded with a cellulose nanofiber (CNF) reinforcement and coupled by a maleic anhydride coupling agent to produce comparable mechanical properties in comparison to the industry-standard method of injection molding (IM). Design/methodology/approach A spray dried CNF (SDCNF) was compounded with the polymer matrix using a masterbatch method. The composite was diluted with neat polymer and extruded into a filament and then printed into standardized mechanical testing samples. For comparison, the filament was chopped and standardized samples were produced with IM. Findings A loss in mechanical properties of up to 30% was observed in FLM samples. If normalized to reflect improved density from a part consolidation method, losses are reduced to 15% or show improvements in the neat polymer matrix. Originality/value Limited research has been done on producing FLM feedstock, reporting mechanical property results based on standardized testing and comparing the same material with IM.

Surface Energetics Effects on Mechanical Strength of Fibre Reinforced Polymer Matrix

Surface energetics effects on the mechanical strength of fibre reinforced polymer matrix been studied employed the manual scraper mechanism in extracting fibre from plantain pseudo-stem and was treated with nine different treatments. Cylindrical shape mould was prepared for mechanical test samples with continuous and unidirectional aligned fibres. Two probe liquids; water and glycerol were used in contact angle measurement for all the treated and untreated samples. The contact angle data was used for the interfacial energetics computations using Neumann and Fowkes models and the mathematical analysis were carried out using Matlab software tools. van der Waals notion of particle-particle interaction was employed to explain the physiochemical properties such as the surface interfacial energies. The average value for the interfacial free energy of adhesion for fibre-water and fibre-glycerol are -10mJ/m2 and -16MJ/m2 respectively signifying attractive van der Waal forces. The tensile test results unveil that the average value for treated fibres is greater than the average value of 171.29N/mm2 for untreated fibre except for potassium permanganate and phosphoric acid. These results reveal that an increase in tensile strength leads to an increase in the interfacial surface energy of adhesion. The treated fibres show a significant increase in interfacial surface energy and change in free energy of adhesion which suggests a better bonding mechanism of interaction between the fibre and matrix except for phosphoric acid which reveals otherwise, it may be as a result of the chemical chopped off the fibre during the treatment. The average strain rate of about 0.003 per seconds, 0.002 per seconds and 0.005 per seconds were deduced from the treated Mercerization, Acetone and MEKP respectively which reveals the lower strain rate as compared to the untreated fibre of 0.008 per seconds. The negative strain rate for the potassium permanganate and phosphoric acid was found to be -0.002 and -0.001 respectively reveals that the treatments will debond faster than other treated fibres..

Reuse of petroleum industrial waste as reinforcement in aluminium matrix for enhancement of mechanical properties

The impelling quest for new materials that can be eco-friendly and results in remarkable properties step up worldwide. Aluminium metal matrix composites are inevitable in diversified fields of production industries as it turned up to have superior mechanical properties. In this current investigation, a new metal was synthesized with pure aluminium as the matrix metal and the petroleum industrial waste as the reinforcement material. The exhausted waste from the petroleum industries are available in tonnes across the world. The elements present in the industrial waste was the main cause that it is chosen for producing aluminium composite. The purpose of research was to reuse the petroleum industrial waste in manufacturing the new composite by stir casting. The proportions of industrial waste were varied such as 0%, 5%, 10% & 15%. The mechanical testing of samples was done and results were compared with pure Aluminium. The hardness of the synthesized composites was greater than pure aluminium. The tensile strength was increased for the new Aluminium Industrial waste composites than pure Aluminium. The composite with 10% industrial waste resulted to be the best composition with enhancement of 45% hardness and 14% tensile strength amongst as the samples. The morphological study of cast composites was analysed by Scanning Electron Microscope and it revealed the even distribution of industrial waste in aluminium matrix. The composition of the composites was observed by the Electron Dispersion Analysis. Aluminium metal matrix composite with improved properties can be manufactured by using petroleum industrial waste without causing negative impact to the environment.

Strength Improvement of Metals Produced by Selective Laser Melting of Powders

Standard samples for mechanical tests have been produced by selective laser melting (SLM) of metal powders of various chemical compositions. It has been determined that strength properties of all SLM samples are higher than those of solid samples of the same chemical composition. It has been established that the factors of strength improvement are vapor condensed nanoparticles above the melting zone and ultrafine grain structure formed at the stage of crystallization.

A comparison study on mechanical properties of virgin and recycled polylactic acid (PLA)

Huge usage of Polylactic Acid (PLA) has contributed to the high wastes which mainly come from the worn parts. Recycling of the wastes is seen to be a permissible solution to reduce the quantity of wastes in the landfills. This work aims to compare the mechanical properties of virgin and recycled PLA. The recycled material is collected from the waste produces from the injection molding process. The mechanical testing samples for both virgin and recycled materials are prepared using an injection molding process. The results show that the mechanical properties of recycled PLA lower than the virgin PLA. The tensile strength of recycled PLA decreases by 11% as compared to virgin PLA. On the other hand, TRS is also observed drop by 5% for recycled PLA compared to virgin PLA. A similar trend is found in the impact strength and hardness of properties where its impact strength drops by 50% of recycled PLA. For hardness property, it is noted that the hardness decreases by 4% of the recycled PLA. The decreasing value of the mechanical properties is due to thermal degradation of the PLA molecular chain during the injection molding process which has consequently affected the mechanical properties of the recycled PLA.

Determination of the dislocation-based mechanism(s) responsible for the anomalous ductility of a class of B2 intermetallic alloys

A class of stoichiometric, ordered MR alloys (where M denotes a metal and R either a rare earth or group IV refractory metal) with B2 (CsCl) crystal structure, were discovered to possess anomalous ductility by researchers at Ames Laboratory in the early 2000’s. Despite active research on the topic for over 15 years, a holistic explanation for the anomalous ductility of these metal alloys has not yet been accepted by the scientific community. The reason for this appears to be a failure to account for all relevant length scales. Researchers either focus on the atomistic length scale relevant to dislocation core structures, the microscopic length scale of dislocations and dislocation ensembles, the mesoscopic length scale of grains and their interactions, or the macroscopic scale of mechanical testing samples with millimetre dimensions or larger. Focused studies at each of these length scales have provided essential, but insufficient information to provide a complete answer to the question. The insight provided by in-situ diffraction studies, along with crystal plasticity modelling as an interpretive tool, and a novel grain-by-grain line profile analysis technique for assessing dislocation densities in polycrystals is highlighted. In addition to the primary <100> dislocations, which are most easily activated in all of these anomalous MR alloys, the results show that dislocations with large Burgers vectors (e.g., <110> and <111>) are present in large numbers beyond a transition in the strain hardening response. The motion of these large Burgers vector dislocations is experimentally observed to occur at stress levels consistent with atomistic modelling predictions of the Peierls resistance and simultaneously provides a satisfying explanation for the anomalous ductility and other experimental results.

The research of the features destruction of the of oxide coatings on aluminum alloy by using the method of acoustic emission

The influence of oxidizing the aluminum product 6070 with different times of micron exposure on the registration of acoustic emission signals (AE) during mechanical testing of samples was investigated. The results of microstructural studies after mechanical tests confirm the mechanism for generating AE signals associated with the destruction of coatings and the effects of plastic deformation on microarc oxidation, the newly formed surfaces of the substrates.

Structural and thermal degradation behaviour of reclaimed clay nano-reinforced low-density polyethylene nanocomposites

In this study, a novel reclaimed clay nanofiller was used to manufacture low-density polyethylene (LDPE)/Oil based mud filler (OBMF) nanocomposites by a melt compounding process. The mechanical testing samples were manufactured using injection moulding. The effect of reclaimed clay minerals influencing the crystallinity and the dispersion characteristics of this clay in LDPE matrix affecting the structural and thermal properties of the nanocomposites was investigated. It was observed that OBMFs were compatible with LDPE matrix which implies a strong interfacial interaction between the clay layers and polymer and that the influence of clay minerals present in OBMFs formed chemical bonds within the microstructure of the nanocomposites. The char yields of nanocomposites increased with OBMFs content. The TD5% and TD50% (onset degradation temperature at 5 wt% loss and 50 wt% loss, respectively) of the LDPE nanocomposite with 10.0 wt% OBMFs was the highest (27 °C higher in TD5% and 54 °C higher in TD50%) among the nanocomposites. Viscoelastic analysis data showed a sharp decrease in the storage modulus of OBMFs reinforced LDPE nanocomposites. The tan δ spectra presented a strong influence of the filler contents on the relaxation process of LDPE and its nanocomposites. An enhancement of mechanical properties of composites was identified which showed a gain of 14% Young’s modulus and a gain of 18% tensile strength at 10.0 wt% OBMFs loading compared to those properties of neat LDPE. The effect of filler dispersion in LDPE polymer matrix in relation to thermal stability was investigated and heat capacity data is employed to characterise changes in thermal characteristics relating to the nanomorphology of the materials.

Propriedades de painéis aglomerados produzidos com madeiras de Ligustrum lucidum e Pinus taeda

Este trabalho teve por objetivo avaliar as propriedades físicas e mecânicas de painéis aglomerados produzidos com madeira de Ligustrum lucidum W.T. Aiton, pura ou com Pinus taeda, e comparar as propriedades desses painéis com os requisitos normativos e com os produzidos somente com Pinus taeda. Os painéis foram produzidos com adesivos uréia-formaldeído e tanino-formaldeído na proporção de 10% de massa de sólido sobre a massa seca de partículas. Para a confecção dos painéis, foi estabelecida massa específica nominal de 0,75 g cm-³, pressão específica de 3,92 MPa, temperatura de 160 °C e tempo de prensagem de 8 min para o adesivo uréia-formaldeído e 10 min para tanino-formaldeído. Após o período de climatização dos painéis, foram confeccionados os corpos de prova destinados aos ensaios físicos e mecânicos. Verificou-se que apenas madeira de Ligustrum lucidum com adesivo tanino-formaldeído, bem como a combinação de madeiras e adesivo uréia-formaldeído, proporcionou aos painéis melhores propriedades físicas e mecânicas. Esses tipos de painéis atenderam aos requisitos normativos de propriedades mecânicas e demonstraram que L. lucidum tem potencial para uso na produção de painéis aglomerados.

Rolling contact fatigue of hot-deformed powder steels with calcium microadditives

Fatigue damage of the surface layers of metal is a characteristic cause of failure of rolling bearings, gears and a number of other machine parts operating under cyclically repeated contact loads. Resistivity to the development of contact damage of steels obtained by hot forging porous blanks is determined by the presence of cohesive bonds between the particles of the base powder, as well as by the presence of non-metallic inclusions and grain size. The possibility of increasing the contact endurance of hot-deformed powder steels due to micro-doping with calcium has been studied. Iron powders with various content of impurities, as well as atomized powder of low-alloyed chromium-molybdenum steel were used as the basis for preparation of the blends. Calcium was doped as calcium carbonate. Mixing was performed in a planetary centrifugal mill. Samples for mechanical testing were obtained by hot forging porous blanks. After hot forging the samples were carburized to compensate for the loss of carbon in the surface layer. It has been established that doping calcium microadditives is favourable for increasing the energy content of damage under the conditions of exposure to contact-fatigue and bending loads. This is due to a decrease in the size of austenite grains at the expense of inhibition of their growth during the adsorption of calcium at the grain boundaries. Microalloying with calcium changes the localization of seats of contact fatigue damage. In samples-witnesses without microadditives of calcium cracks originate near non-metallic inclusions of sharp-angled shape in the near-surface zone. In microalloyed specimens the cracks are located in the subsurface layer in the area of Hertz maximum shear stresses.

Acoustic emission that occurs during the destruction of coatings applied by microarc oxidation on an aluminum alloy

Abstract The paper presents the results of the analysis of acoustic emission (AE) parameters recorded during mechanical testing of samples with oxide coatings deposited on the surface by microarc oxidation. The results of microstructural studies after mechanical testing confirm the mechanism of the AE signals generation associated with the destruction of the coating and the plastic deformation of the material on the newly emerged surfaces.

Evaluation of Mechanical Properties of Orange Peel Reinforced Epoxy Composite

Abstract The mechanical behaviour of orange peel reinforced with epoxy composites is investigated by increasing the percentage of the orange peel reinforcement mechanical properties in the developed composite. Composite having 10%, 20% and 30% weight fraction of orange peel was made using hand layup method. Samples for different mechanical testing were prepared according to ASTM standards to check the hardness, tensile strength and density. Experiments were conducted on prepared samples and orange peel epoxy composite with the finding that 20% fibre percentage is optimum.

Strontium Oxide Deposited onto a Load-Bearable and Porous Titanium Matrix as Dynamic and High-Surface-Contact-Area Catalysis for Transesterification.

Strontium oxide (SrO) deposited onto a porous titanium (Ti)-based scaffold (P-Ti) is a promising and novel approach for high-throughput transesterification. Notably, a highly porous and calcinated scaffold provides a load-bearable support for a continuous process, while the calcinated SrO catalyst, as it is well distributed inside the porous matrix, can extend its surface contact area with the reactant. In this work, the formation of transesterification reaction with the conversion and production of olive oil to biodiesel inside the porous matrix is particularly examined. The as-designed SrO-coated porous titanium (Ti)-based scaffold with 55% porosity was prepared via a hydrothermal procedure, followed by a dip coating method. Mechanical tests of samples were conducted by a nanoindentator, whereas the physical and chemical structures were identified by IR and Raman Spectroscopies. The results implied that SrO catalysts can be firmly deposited onto a load-bearable, highly porous matrix and play an effective role for the transesterification reaction with the oil mass. It is promising to be employed as a load-bearable support for a continuous transesterification process, such as a process for batch or continuous biodiesel production, under an efficient heating source by a focused microwave system.