Average Modulus Research Articles

Nanomechanical Mapping of Three Dimensionally Printed Poly-ε-Caprolactone Single Microfibers at the Cell Scale for Bone Tissue Engineering Applications.

Poly-ε-caprolactone (PCL) has been widely used in additive manufacturing for the construction of scaffolds for bone tissue engineering. However, its use is limited by its lack of bioactivity and inability to induce cell adhesion, hence limiting bone tissue regeneration. Biomimicry is strongly influenced by the dynamics of cell-substrate interaction. Thus, characterizing scaffolds at the cell scale could help to better understand the relationship between surface mechanics and biological response. We conducted atomic force microscopy-based nanoindentation on 3D-printed PCL fibers of ~300 µm thickness and mapped the near-surface Young's modulus at loading forces below 50 nN. In this non-disruptive regime, force mapping did not show clear patterns in the spatial distribution of moduli or a relationship with the topographic asperities within a given region. Remarkably, we found that the average modulus increased linearly with the logarithm of the strain rate. Finally, a dependence of the moduli on the history of nanoindentation was demonstrated on locations of repeated nanoindentations, likely due to creep phenomena capable of hindering viscoelasticity. Our findings can contribute to the rational design of scaffolds for bone regeneration that are capable of inducing cell adhesion and proliferation. The methodologies described are potentially applicable to various tissue-engineered biopolymers.

Shear wave elastography for lower extremity deep vein thrombosis

Aim. To evaluate the potential of shear wave elastography to determine the duration of lower extremity deep vein thrombosis, the effectiveness of direct anticoagulation and patient management strategy.Material and methods. Duplex lower extremity vein scanning, supplemented by shear wave elastography with determination of the average, minimum and maximum Young's modulus, was performed in 98 patients with acute, subacute and chronic thrombosis of the iliac and femoral veins on days 1, 3 and 6 of hospitalization. Based on the coefficient of determination (R2) of the median Young's modulus of a venous thrombus at different stages of thrombosis, the significance of its changes was assessed. Diagnostic information content of Young's modulus was calculated by comparing with the histological data of 17 blood clots removed during surgery.Results. As the age of both iliac and femoral vein thrombus increased, the median of the maximum, average and minimum Young's modulus at all stages of thrombosis steadily increased (R2=0,99). The median of the average Young's modulus at the acute stage was determined to be <17 kPa; at the subacute stage — in the range of 17-32 kPa and chronic — >32 kPa. According to shear wave elastography, in patients with acute and subacute stages of thrombosis, by the 6th day of anticoagulant therapy, the thrombus stiffness increased (R2=0,91-0,96), while in the chronic thrombosis group only a tendency to decrease was observed. The diagnostic information value of studying a thrombus using shear wave elastography relative to its histological examination turned out to be sufficient for use in clinical practice. In acute femoral vein thrombosis, the indication for radical treatment was the average Young's modulus ≤8,1 kPa, the minimum Young's modulus ≤1,7 kPa (sensitivity, specificity, positive and negative predictive values varied in the range of 64,3-88,9%); in subacute — ≤23,0 kPa and ≤11,3 kPa, respectively (55,6-100%).Conclusion. The results indicate that the diagnostic information value of shear wave elastography indicators is sufficient to determine the stage of lower extremity deep vein thrombosis in clinical practice.

Water absorption of biomass fillers to impact the degradation of poly(butyleneadipate‐co‐terephthalate) composites

AbstractIn this work, two kinds of biomass fillers including reed and wheat straw with similar sizes at micrometer scale were used as filler and poly(butyleneadipate‐co‐terephthalate) (PBAT) as matrix to prepare high‐performance composite materials and to use for the research of enzymatic degradation. Accordingly, hard PBAT composites with average bending strength and modulus at 12 and 1100 MPa were prepared. With the progress of enzymatic degradation, water absorption of the biomass fillers to promote the degradation of PBAT matrix was clearly revealed. The strong water absorption of biomass filler led to the large degradation rate. During the degradation within 90 days, the mechanical properties of PBAT/biomass fillers composites decreased to 23.7%. This study revealed the important factors of biomass fillers affecting the degradation behavior of PBAT in composite.Highlights• Two different biomass fillers are blended into PBAT to fabricate the composites.• All of the biomass fillers are similarly controlled at the micrometer level.• Water absorption of biomass filler promotes the degradation of the PBAT matrix.• Stronger water absorption induces quicker degradation rate.• After degradation, bending properties of PBAT composites obviously decrease.

Effect of fabrication process on the microstructure and mechanical performance of carbon fiber reinforced PEEK composites via selective laser sintering

Carbon fiber reinforced PEEK (CF/PEEK) composites via selective laser sintering (SLS) are highly promising technologies for the fabrication of polymer-based components with excellent mechanical behavior. In order to further enhance the performance of SLS-CF/PEEK composites, the mixed CF/PEEK powders are designed and CF/PEEK composites are fabricated via SLS under different fabrication process parameters. The effect of laser power, layer thickness, paving speed, fiber weight fraction, and fiber length on the microstructure and mechanical performance along the powder spreading direction is investigated for SLS-CF/PEEK. The results show that the failure strength of 117 MPa is achieved while the layer thickness of 0.08 mm is adopted. Moreover, the fiber weight fraction of 15% is proven to be suited during the fabrication of SLS-CF/PEEK. The maximum failure strength is better than the results of SLS-CF/PEEK with the fiber weight fraction of 10%, and the average elastic modulus reaches 8400 MPa, which is the best result among those published works. In addition, it is found that the correlation between the failure strength and paving speed is non-monotonic, and the higher strength is obtained when the longer carbon fiber is used. Different from the distinct trends in failure strength, the sensitivity of modulus is much less obvious for SLS-CF/PEEK. This work provides guidance for the printing of high-strength CF/PEEK composites.

Effects of average number of platelets through the thickness and platelet width on the mechanical properties of discontinuous fiber composites

In this study, we experimentally and numerically investigate the evolution of the tensile material properties of Discontinuous Fiber Composites (DFCs) with an increasing average number of platelets through the thickness for two different platelet widths.The results show that both the number of platelets and the platelet width have significant effects on the tensile modulus and strength. We find that not only the average mechanical properties but also their coefficients of variation change according to the different DFC mesostructures.To understand the relationship between material morphology at the mesoscale and corresponding material properties, we developed a random platelet mesostructure generation algorithm combined with explicit finite element models. Leveraging the computational tools, we find that moduli and strength increase with increasing average number of platelets through the thickness. The increasing trend continues until reaching an asymptotic limit at about 45 layers through the thickness for the narrow and 27 layers for the square platelets.In the study, we address the importance of having accurate simulations of the mesostructure to match not only the average modulus and strength but also their associated coefficients of variation. We show that it is possible to accurately predict the tensile material properties of DFCs, including their B-basis design values. This is a quintessential condition for the adoption of DFCs in structural applications.

Viscoelastic response of gray matter and white matter brain tissues under creep and relaxation

Accurate measurement of the mechanical properties of brain tissue is of paramount importance for understanding its mechanics-biology relationship. Most published studies on brain viscoelasticity have been conducted using a single relaxation test, without validating the validity of linear viscoelasticity, which is insufficient to establish an accurate constitutive equation for brain tissue. We obtained the creep and relaxation profiles of fresh adult porcine white matter (N = 120) and gray matter (N = 56) under finite step-and-hold uniaxial compression, using a mechanical testing machine, with 16.67 mm/s loading rate and 80 s hold time. These curves were employed to determine viscoelastic properties and demonstrated an excellent fit with a concise power-law function. The average initial modulus for gray matter (GM) was 6.619 kPa, higher than that for white matter under transverse loading (WM-2D) at 5.579 kPa (p < 0.01), yet lower than that for white matter under axial loading (WM-1D) at 6.759 kPa (p = 0.0121). Notably, WM-2D exhibited the highest degree of fluidity (β = 0.216). Our findings reveal that gray matter behaves as a linear viscoelastic material with power-law creep compliance and relaxation modulus. Conversely, the creep and relaxation behavior of white matter deviates from the verification relationship derived from linear viscoelastic theory, indicating its nonlinearity. This fact underscores the inaccuracy of assuming a linear constitutive relationship to characterize the viscoelastic properties of white matter. By combining the power-law function with the experimentally obtained creep compliance and relaxation modulus, we offer a unique approach to determining the viscoelastic characteristics of brain tissue.

Spatio-temporal variation in soil erosion on sloping farmland based on the integrated valuation of ecosystem services and trade-offs model: A case study of Chongqing, southwest China

Mastering the spatio-temporal evolution of soil erosion on regional sloping farmland is crucial for optimizing erosion control planning and carrying out soil quality evaluations. To simulate the potential or net soil erosion on sloping farmland in Chongqing, China, this study analyzed the temporal and spatial variation features of soil erosion using the integrated valuation of ecosystem services and trade-offs (InVEST) model and other models. The InVEST model was applied to calculate the soil erosion modulus on sloping farmland, hotspot analysis was used to identify hot and cold spots of sloping farmland erosion, and the chord diagram visualization model was used to reflect the transformation quantity and flow direction relationship between different erosion levels of sloping farmland transfer processes in different periods. The results showed that soil erosion on sloping farmland in Chongqing presents a distribution pattern of high values of soil erosion in the northeast and low values in the southwest. Very strong and severe erosion is concentrated in the low mountainous hilly areas in the northeast and southeast of Chongqing, while slightly and lightly eroded areas are distributed in the western and central flatter areas. The soil erosion grade of most sloping farmland is light and middle; in addition, the annual average soil erosion modulus shows a decreasing trend. Only in 2000 was it in the middle erosion grade. The areas with strong, very strong and severe erosion showed a downward trend, with the proportion decreasing from 18 % to 11 %. The average erosion modulus with slope > 25° was the largest (7553 t·km−2·a-1) and presented strong erosion. Soil erosion in sloping farmland mainly occurs between 400 and 1600 m of elevation. This research can effectively improve soil erosion control and quality control of sloping farmland and provide a reference for the sustainable development of land use in the region.

Tensile forces in the neurovascular bundle: A contributor to orthodontic relapse?

The aim of this study is to investigate the neurovascular bundle (NVB) as a potential orthodontic relapse factor. The mechanical properties and the forces generated in the NVB after orthodontic extrusion are explored. Six NVBs branching from the inferior alveolar nerve to the apices of the mandibular canines and premolars of mature pigs were harvested. Stress relaxation tests were conducted. A standard linear solid model (SLS) was utilized to simulate the orthodontic extrusion of a single rooted tooth with NVB length and cross-sectional diameter of 3.6 and 0.5 mm, respectively, so the NVB was stretched 10% and 20% of its original length. The maximum force within the NVB was then calculated. Based on our data, the average Young's modulus before relaxation ( ), after relaxation ( ) and the difference between Young's moduli before and after relaxation ( ) were 324 ± 123, 173 ± 73 and 151 ± 52 kPa, respectively. The theoretical force within the NVB stretched to 10% and 20% strain was 3 and 5 mN, respectively. The data from our study indicate that the NVB exhibits stress relaxation, a characteristic trait of viscoelastic materials. SLS model simulation predicted residual forces around 5 mN for elongation up to 20%. We observed strain hardening with additional elongation, which has the potential to cause forces to increase exponentially. Therefore, tensile forces in the NVB should not be ruled out as a contributor to orthodontic relapse, especially in adult patients who may have decreased adaptability of their NVB. Further preclinical and clinical models should be developed to further clarify what is the contribution of the NVB to orthodontic relapse.

The experimental Young’s modulus of polythiophene nanofibers

The Young’s modulus of polythiophene (PT) nanofibers has not been reported so far. In this paper, PT nanofibers were electrolytically prepared from thiophene monomer with a porous anodic aluminum oxide template. The Young's modulus of individual PT nanofibers was measured using atomic force microscopy. The average Young's modulus of PT nanofibers with diameters around 90 nm was 64.5 ± 5.0 GPa, which is an order of magnitude higher than its bulk value. We attribute the high Young’s modulus of PT nanofibers to the alignment of the molecular chain.

Construction of a dual-component hydrogel matrix for 3D biomimetic skin based on photo-crosslinked chondroitin sulfate/collagen

The main challenge in the field of 3D biomimetic skin is to search for a suitable hydrogel matrix with good biocompatibility, appropriate mechanical property and inner porosity that can support the adhesion and proliferation of skin cells. In this study, photocurable chondroitin sulfate methacrylate (CSMA) and collagen methacrylate (CoLMA) synthesized from chondroitin sulfate (CS) and type I collagen I (CoL) in the dermal matrix were used to construct a photo-crosslinked dual-component CSMA-CoLMA hydrogel matrix. Due to the toughening effect of the dual-component, the CSMA-CoLMA hydrogel improved the intrinsic brittleness of the single-component CSMA hydrogel, presented good mechanical tunability. The average storage and elasticity modulus could reach 3.3 KPa and 30.3 KPa, respectively, which were close to those of natural skin. The CSMA-CoLMA hydrogel with a ratio of 8/6 showed suitable porous structure and good biocompatibility, supporting the adhesion and proliferation of skin cells. Furthermore, the expression of characteristic marker proteins was detected in the epidermal and dermal bi-layered models constructed with the hydrogel containing keratinocytes and fibroblasts. These results suggest that the dual-component CSMA-CoLMA hydrogel has promising potential as a matrix to construct 3D biomimetic skin.

A Study on Damage of T800 Carbon Fiber/Epoxy Composites under In-Plane Shear Using Acoustic Emission and Digital Image Correlation.

In addition to measuring the strain, stress, and Young's modulus of materials through tension and compression, in-plane shear modulus measurement is also an important part of parameter testing of composites. Tensile testing of ±45° composite laminates is an economical and effective method for measuring in-plane shear strength. In this paper, the in-plane shear modulus of T800 carbon fiber/epoxy composites were measured through tensile tests of ±45° composite laminates, and acoustic emission (AE) was used to characterize the damage of laminates under in-plane shear loading. Factor analysis (FA) on acoustic emission parameters was performed and the reconstructed factor scores were clustered to obtain three damage patterns. Finally, the development and evolution of the three damage patterns were characterized based on the cumulative hits of acoustic emission. The maximum bearing capacity of the laminated plate is about 17.54 kN, and the average in-plane shear modulus is 5.42 GPa. The damage modes of laminates under in-plane shear behavior were divided into three types: matrix cracking, delamination and fiber/matrix interface debonding, and fiber fracture. The characteristic parameter analysis of AE showed that the damage energy under in-plane shear is relatively low, mostly below 2000 mV × ms, and the frequency is dispersed between 150-350 kHz.

Micromechanical Characterization of Continuous Fiber Date Palm Composites

ABSTRACT Date palm fiber composites with aligned, continuous fibers and epoxy matrix were prepared and mechanically characterized using micromechanical models. A hydrothermal process with microwave heating was utilized to extract the date palm frond (midrib) fibers, making the process eco-friendly as opposed to the commonly reported chemical extraction method. Single fibers were then characterized and found to have an average elastic modulus and ultimate tensile strength of 17.1 ± 1.5 GPa and 333 ± 27.4 MPa, respectively. Interfacial shear strengths ranging between 6 and 12 MPa were determined using a single-fiber pull-out test. Fibers were aligned to make uniaxial tensile samples with volume fraction ranging from 11% to 56%, elastic modulus ranging from 1.72 GPa to 9.52 GPa and ultimate tensile strengths ranging from 16.9 MPa to 43.8 MPa. All the results were found to obey “Rule of Mixtures” theory. The composite’s mechanical properties are similar to or exceeding those of the commercially available wood products such as medium density fiberboard, oriented strand board, thick particle board, hard fiber board, and plywood, making the hydrothermal approach with microwave heating as a promising approach for preparation of date palm composites and further opens up similar process pathway for other natural fibers.

Microstructure and mechanical properties of cold spray additive manufactured and post heat treated high-entropy alloys with mixed CoCrFeNi and Ti powders

Solid-state cold spray additive manufacturing has the potential to fabricate high-strength bulk high-entropy alloys (HEAs). Through systematic experiments, this study examined the microstructure and mechanical properties of cold spray fabricated bulk HEAs with mixed CoCrFeNi and Ti powders and explored the effects of Ti content in 4 and 7 at% and post-heat treatment at 800 °C/6 h and 1000 °C/6 h. It is found that the bulk HEAs are highly densified and remain nearly defect-free after the post-heat treatment. The addition of Ti serves as an mixing powder effect to further densify the alloys. Moreover, the addition of Ti and post-heat treatment promote the formation of fine precipitates, including Fe2Ti, Co2Ti, CrFe, CoTi2, and Ni3Ti, which contributes to the strengthening of the alloys. Furthermore, post-heat treatment improves the cohesion of the alloys and yields fine and relatively uniform grains by stimulating static recovery and recrystallization. These synergistic effects improve the hardness, elastic modulus, strength, and ductility properties. The average hardness and elastic modulus of the bulk alloys are as high as 377.6 HV and 94.8 GPa, respectively; the best ultimate tensile strength and elongation to failure are 626.7 MPa and 22.1 %, respectively. Synchrotron X-ray diffraction validates the complex precipitates formed and confirms that there is no phase change during tension. The study offers insights into the microstructure and mechanical properties of cold spray additive manufactured HEAs and the effects of mixed powders and post-heat treatment on tuning microstructure and properties.

Mechanical behavior and microstructure of porcine brain tissues under pulsed electric fields.

Pulsed electric fields are extensively utilized in clinical treatments, such as subthalamic deep brain stimulation, where electric field loading is in direct contact with brain tissue. However, the alterations in brain tissue's mechanical properties and microstructure due to changes in electric field parameters have not received adequate attention. In this study, the mechanical properties and microstructure of the brain tissue under pulsed electric fields were focused on. Herein, a custom indentation device was equipped with a module for electric field loading. Parameters such as pulse amplitude and frequency were adjusted. The results demonstrated that following an indentation process lasting 5s and reaching a depth of 1000 μm, and a relaxation process of 175s, the average shear modulus of brain tissue was reduced, and viscosity decreased. At the same amplitude, high-frequency pulsed electric fields had a smaller effect on brain tissue than low-frequency ones. Furthermore, pulsed electric fields induced cell polarization and reduced the proteoglycan concentration in brain tissue. As pulse frequency increased, cell polarization diminished, and proteoglycan concentration decreased significantly. High-frequency pulsed electric fields applied to brain tissue were found to reduce impedance fluctuation amplitude. This study revealed the effect of pulsed electric fields on the mechanical properties and microstructure of ex vivo brain tissue, providing essential information to promote the advancement of brain tissue electrotherapy in clinical settings.

A comprehensive micro-nano investigative approach to study the development of aluminosilicate gel in binary blends of lithium slag geopolymer

This study extensively investigates the formation of aluminosilicate gel in binary blends of lithium slag geopolymer (LSG) containing fly ash and silica fume. A comprehensive analysis of the aluminosilicate gel was performed at the micro-nano scale, employing techniques such as mineralogical, crystallographic, micromorphological, and micromechanical analysis. C-(N)-A-S-H and N-(C)-A-S-H gels were found between Si/Al ratios of 2.41–3.04 and 3.88 to 4.33, respectively. Fly ash incorporated LSG at 45% alkaline activator yielded the highest average nano-indented modulus of 22.54 GPa. Statistical Gaussian deconvolution was employed to categorize mineral phases in nano-indentation of LSG, revealing substantial distinctions indicated by the low p-values. Carbonation in silica fume incorporated LSG was affirmed by selected area electron diffraction (SAED) patterns of calcite crystallites. The microstructure of LSG containing fly ash was stiffened by the growth of needle crystals of hydroxy-sodalite and aluminosilicate gel. Thus, the formation of C-(N)-A-S-H gel and hydroxy-sodalite governs the strength development of LSG binary blends.

Investigation of Ti alloying for microstructural evolution and strengthening mechanism: Avoiding Al4C3 formation in SiCp/Al composites via laser directed energy deposition

The near-net-shape characteristics of Additive Manufacturing offer significant advantages in fabricating SiCp/Al composite components. However, the high-temperature melt pool during the deposition process promotes an interface reaction between SiC and Al, forming Al4C3. Al4C3 shortens the service life of SiCp/Al composite structural components, so it is critical to avoid its formation when preparing SiCp/Al composites via laser-directed energy deposition. This study prepared SiCp/Al composite components through coincident wire powder laser-directed energy deposition with Ti alloying, effectively preventing the formation of Al4C3 in AMC. Furthermore, it investigated the effect of Ti atoms on the microstructural evolution and strengthening mechanism. The results showed that the formation of large flake-like Al4C3 was avoided without generating excess Al3Ti only when using an appropriate amount of Ti (Ti: SiC = 3: 10). After introducing Ti, Ti atoms in the melt pool migrated towards the SiC surface and reacted with C atoms (from the dissolution of SiC) and formed TiC. The resulting TiC enclosed the SiC particles in a thin film, preventing the further dissolution of SiC and inhibiting the generation of Al4C3. Additionally, some TiC nanoparticles dispersed within the matrix, serving as heterogeneous nucleation sites for Al, reducing the average equivalent circular grain radius from 38.10 µm to 7.20 µm. After Ti alloying, the average modulus and yield strength of AMC both increased. This increase was attributed to the load transfer energy of SiC particles, grain refinement of the matrix, and the dispersion-strengthening effect of TiC nanoparticles. An intrinsic relationship between the SiC-Al-Ti interfacial reaction and the mechanical properties of SiCp/Al composites has been established to provide theoretical guidance for eliminating Al4C3 phases in SiCp/Al composites prepared by laser-directed energy deposition, ensuring performance comparable to traditionally fabricated products.

The suitability of common reed (Phragmites australis) for load-bearing structural materials

Besides wood, the most widely used natural structural material, dicotyledonous fibre plants such as flax or hemp, and monocotyledonous grasses such as cereal straw or bamboo have been shown to be suitable for application in materials. Common reed is a less well-characterised plant resource in this regard. Therefore, common reed stems were characterised in uniaxial tension in the present study, aiming at acquiring basic information about the mechanical characteristics of this material. Furthermore, laboratory-scale composite beams were manufactured and tested in bending. Compared to wood species with similar density, common reed stem walls showed a comparable average modulus of elasticity of 8 GPa and a very good average tensile strength of 150 MPa. After a mild alkali pre-treatment, reed showed excellent adhesive bonding, enabling the manufacture of high-density composite beams with roughly 130 MPa bending strength and 12–13 GPa modulus of elasticity. Same as untreated common reed stem walls, also reed biocomposite beams compared very favourably with established wood-based materials of similar structure, density, and adhesive content. In summary, it was thus demonstrated that common reed is a highly suitable raw material for bio-based load-bearing structural materials.

18Ni300/Inconel 625 alloy gradient materials fabricated by directed energy deposition

Functionally graded materials (FGMs) exhibit high fusion, which offer a potential solution to the issue of performance degradation caused by the inconsistency of thermal expansion coefficient and elastic modulus of different materials. As an advanced additive manufacturing method, directional energy deposition is widely used in the preparation of FGMs. This work focuses on characterizing the microstructure and compressive strength of 18Ni300/Inconel 625 gradient materials with varying composition ratios in the as-built state, prepared using powder directed energy deposition technology. The microstructure of the 18Ni300/Inconel 625 gradient materials includes columnar grains and cellular grains, and the phase mainly includes martensite (α-Fe) and γ-Ni. FGMs have a maximum hardness of 348 HV0.2 and a minimum coefficient of friction of 0.2588. Compared with the single materials, the mechanical compression performance of the gradient materials were basically consistent in three different orientations, with a maximum compression modulus of 3165.14 MPa of OD orientation. The average compressive moduli of FGMs is 2957.89 Mpa. The design and preparation of high-performance functionally graded materials provides an in-depth mechanistic understanding of improving the fusion of different materials.

Biochar reinforced PLA composite for fused deposition modelling (FDM): A parametric study on mechanical performance

Rice husk biochar was added to polylactic acid (PLA) to create a biocomposite filament suitable for the extrusion-based 3D printing process of fused deposition modelling (FDM). Taguchi L16 was used for experiment design, and the significance of process parameters was determined using variance analysis (ANOVA). For a 0.3-mm layer thickness, the addition of 5 wt.% biochar resulted in ultimate tensile strength and a modulus of elasticity of 36 MPa and 1103 MPa, respectively. The addition of biochar had a negative influence on flexural strength. The maximum flexural modulus was obtained with 3 % biochar, 100 % infill density, and 0.1 mm layer thickness. Particularly, 1 % biochar resulted in a considerable increase in impact strength, while a subsequent rise in biochar resulted in a decrease, probably due to the agglomeration effect. For 3D printed neat PLA, the average tensile strength, tensile modulus, flexural strength, flexural modulus, and impact strength observed were 19 MPa, 550 MPa, 54 MPa, 1981 MPa, and 25 KJ/m2, respectively. Additionally, considering the output of each test, a multicriteria decision-making model, namely, TOPSIS, has been utilized for ranking the mechanical performance. In order to optimise the mechanical properties of three-dimensional printed objects, the study suggests a layer thickness of 0.2 mm, an infill density of 100 %, and raster angle of 0° as the FDM process parameters.

The Utilization of Coconut Fiber and Marble Waste with Mechanical Tests

The area of coconut plantations in South Aceh Regency was 6839 Ha, out of the total number of sub-districts in South Aceh. South Kluet District was the area with the largest coconut plantation area compared to other districts, reaching 1433 Ha. Coconut coir fiber was usually used for household equipment, such as floor brooms, doormats and rope. Coconut farmers rarely process coconut husks, and after harvest, they just leave the coconut husks piled up under the coconut trees until they rot. In this research, coconut fiber waste was used as reinforcing fiber for composite materials. The aim of this research was to be determined the mechanical strength of marble waste composites mixed with resin and reinforced with coconut fiber. The composition tests carried out were: 85 : 10 : 5, 80 : 10 : 10, 90 : 7.5 : 2.5, and 80 : 12.5 : 7.5. The test carried out on each test specimen composition was a tensile test. From the results of the tests carried out on the test specimens, the maximum stress was found in the composition: (85: 10: 5) 85% Resin, 10% Marble, 5% Coconut Fiber with an average maximum stress value of 29.44827586 N /m2 and the average modulus of elasticity is 0.2415123283 N/m2.