Increase In Tensile Stress Research Articles

Research on the influences of confining pressure and strain rate on NEPE propellant: Experimental assessment and constitutive model

In order to study the influences of confining pressure and strain rate on the mechanical properties of the Nitrate Ester Plasticized Polyether (NEPE) propellant, uniaxial tensile tests were conducted using the self-made confining pressure system and material testing machine. The stress-strain responses of the NEPE propellant under different confining pressure conditions and strain rates were obtained and analyzed. The results show that confining pressure and strain rate have a remarkably influence on the mechanical responses of the NEPE propellant. As confining pressure increases (from 0 to 5.4 MPa), the maximum tensile stress and ultimate strain increase gradually. With the coupled effects of confining pressure and strain rate, the value of the maximum tensile stress and ultimate strain at 5.4 MPa and 0.0667 s−1 is 2.03 times and 2.19 times of their values under 0 MPa and 0.00333 s−1, respectively. Afterwards, the influence mechanism of confining pressure on the NEPE propellant was analyzed. Finally, based on the viscoelastic theory and continuous damage theory, a nonlinear constitutive model considering confining pressure and strain rate was developed. The damage was considered to be rate-dependent and pressure-dependent. The constitutive model was validated by comparing experimental data with predictions of the constitutive model. The whole maximum stress errors of the model predictions are lower than 4% and the corresponding strain errors are lower than 7%. The results show that confining pressure can suppress the damage initiation and evolution of the NEPE propellant and the nonlinear constitutive model can describe the mechanical responses of the NEPE propellant under various confining pressure conditions and strain rates. This research can lay a theoretical foundation for analyzing the structural integrity of propellant grain accurately under working pressure loading.

Coupled static and dynamic tensile property of granite

The principle of coupled static and dynamic loading is illuminated according to the basic principle of the SHPB, i.e., one-dimensional stress wave propagation and uniformity of the specimen. In the Tianhu area of Xinjiang Province, which is a preselected area for high-level radioactive waste geological disposal, a series of coupled static and dynamic loading was conducted in a borehole. The dynamic tensile strength could reach a maximum level when the axial tensile stress is about 50% of the static tensile strength. Meanwhile, as the axial tensile stress increases, the coupled static and dynamic tensile strength increases obviously, reaching about three times the static tensile stress and about 1.5 times the dynamic tensile strength. The failure model of the coupled test is a tensile failure pattern, which is the same as in the static tension and conventional dynamic loading test. Furthermore, through a series of coupled static and dynamic loadings, the strength of the rock specimen could be obtained under different kinds of axial tensile stress and dynamic loading. Thus, the critical value of the dynamic loading could be confirmed, which is useful for blasting excavation in deep geoengineering.

Experimental Research on Tensile Mechanical Properties of NEPE Propellant under Confining Pressure

AbstractTo study the tensile mechanical properties of the Nitrate Ester Plasticized Polyether (NEPE) propellant under varying confining pressure conditions, uniaxial tensile tests were conducted under different strain rates (from 0.0006667 s−1 to 0.06667 s−1) and confining pressure conditions (from relative atmospheric pressure up 5.4±0.03 MPa) using a new‐designed confining pressure testing machine. Scanning electron microscopy (SEM) was employed to observe the tensile fracture surfaces. The mechanical properties and damage processes of the NEPE propellant under varying confining pressure conditions were studied and analysed. The results indicate that the mechanical properties of propellant materials are remarkably influenced by the varying confining pressure conditions. The ultimate strain and maximum tensile stress increase with increasing confining pressure. Moreover, the maximum tensile stress present a linear‐log relationship with the strain rate under various confining pressure conditions. Yet, the confining pressure has no obvious effect on the initial elastic modulus. The reason for the change of the mechanical properties of the NEPE propellant is that confining pressure delays the initiation and development of damage under the tensile loading. Based on the time‐pressure superposition principle (TPSP), the master curve of maximum tensile strength of the NEPE propellant was constructed. Furthermore, the results can provide a theoretical foundation for the analysis of the structural integrity of propellant grains of a SRM under ignition conditions. Finally, a constitutive model considering compressibility of propellant materials can be constructed.

Effects of MgSiO3 on the crystal growth and characteristics of type-Ib gem quality diamond in Fe–Ni–C system* *Project supported by the National Natural Science Foundation of China (Grant Nos. 51772120, 51872112, and 11804305), the China Postdoctoral Science Foundation (Grant No. 2017M622360), and the Project of Jilin Science and Technology Development Plan (Grant No. 20180201079GX).

We report the effects of MgSiO3 addition on the crystal growth and characteristics of type-Ib diamonds synthesized in Fe–Ni–C system. The experiments were carried out with pressure at 5.5 GPa, temperature at 1385 °C–1405 °C, and duration of 23.1 h. As MgSiO3 increases from 0.0 wt% to 3.0 wt%, the diamond growth temperature increases from 1385 °C to 1405 °C, the addition of MgSiO3 and the movement of P–T diagram toward the higher temperature direction result in a series of effects to the Fe–Ni–C system and crystal growth. Firstly, it increases the content of metastable recrystallized graphite and accelerates the competition with the carbon source needed for diamond growth, thus causing the decreased crystal growth rate. Diamond crystals exhibit the combination form of {111}, {100}, {113}, and {110} sectors, the decreased {100} and {113} sectors, dominated {111} sector are all attributed to the higher growth rate in [100] direction caused by the synergy of MgSiO3 and the movement of P–T diagram. The higher growth rate in [100] direction also increases the metal catalyst and graphite inclusions and leads to the increase of residual tensile stress on the crystal surface. Accompanying with the high growth rate, a higher dissolution rate along [100] and [113] directions than [111] direction occurs at the microstructure and forms the significantly developed (111) stepped growth layer. In addition to the movement of P–T diagram, the addition of MgSiO3 poisons the catalyst and increases the nitrogen content of diamond from 120 ppm to 227 ppm.

PHYSICOMECHANICAL PROPERTIES OF COMPOSIT MATERIALS ON BASIS OF COPPER AND POLYOLEFINS

The paper presents the results of a study of the effect of copper concentration on the physicomechanical properties of composites based on high density polyethylene and low density polyethylene. The properties of metal-filled composites, such as ultimate tensile stress, elongation at break, elastic module, melt flow rate, and heat resistance, were studied. Loading of copper into the composition of low density polyethylene contributes to a monotonic increase in the ultimate tensile stress and the elastic module. When copper is loading into the composition of high density polyethylene, on the contrary, a natural decrease in the ultimate tensile stress and elongation at break of the composites is observed. It is shown that when using a compatibilizer, which is polyethylene modified with maleic anhydride, a significant increase in the ultimate tensile stress of high and low density polyethylene composites is observed. A schematic representation of the structure of composites with an interpretation of the probable mechanism of hardening of the material in the presence of a compatibilizer is given. It is shown that the crystallinity of the initial polyethylene has a significant effect on the hardening effect of composites. It is assumed that polyethylene of high density macrochains free of maleic anhydride are involved in the formation of crystalline formations, and small sections of macrosegments containing polar groups are concentrated mainly in amorphous regions and in defects in crystalline structures in the form of passage chains. The concentration of copolymer of polyethylene with maleic anhydride macrosegments in the narrow amorphous space of polyethylene of high density favorably affects the increase in the adhesive forces of interaction on the surface of copper particles, which affects the preservation of the ultimate tensile stress at a relatively high level over a wide range of copper concentrations.

Rut Depth Characteristics on Hot Mix Asphalt with Addition Nano Crumb Rubber

The pavement construction is designed by considering the factor of resistance to deformation due to the repetition of wheel loads. Other factors are the influence of the wheel load, the condition of the increase in temperature on the road surface, which is the cause of the decrease in the strength of the road surface layers. The deformation of the road surface due to wheel tracks occurs when an increase in tensile stress at high temperatures due to wheel loads occurs. The relationship between the number of wheel tracks and permanent stresses that occur on the road surface can be known to be analyzed through the wheel tracking test. This study aims to determine the effect of the addition of nano-sized use of rubber tires on increasing the resistance of hot mix asphalt to the effect of temperature due to vehicle wheel loads. This use of tire waste has been processed to nano-sized granules called nano crumb rubber; this material is added to the Asphalt Concrete Wearing Course hot mix asphalt. This material addition of 0%, 1.25%, 2.5%, 3.75%, and 5% of the asphalt content in hot mix asphalt. The Nano Crumb Rubber is added to the aggregate at the mixing temperature 130℃, before mixing the aggregate with asphalt. The optimum asphalt content is obtained through a Marshall standard test; the research is continued by conducting the Wheel Tracking Machine test. The results of the test found that the addition of Nano Crumb Rubber in the asphalt mixture will improve the quality of the mixture, especially at high temperatures, increase the quality of the addition of 1.25% and continue the addition of 5%. However, the addition of Nano Crumb Rubber > 1.25% decreased performance due to high temperatures. The test results at 40&#8451 and 60&#8451 with the addition of 1.25% are the hot mix asphalt with the best performance. The use of Nano Crumb Rubber in hot mix asphalt requires a smaller amount compared to Crumb Rubber.

Fabrication and evaluation of structural, thermal, mechanical and optical behavior of epoxy–TEOS/MWCNTs composites for solar cell covering

In the present study, hybrid organic–inorganic composites were fabricated from epoxy–TEOS (tetraethyl orthosilicate, Si(OC2H5)4) with various ratios (0–10 wt%) of multiwall carbon nanotubes (MWCNTs) as reinforcing nanofillers by the sol–gel method. The effect of the MWCNTs ratios on the structural, optical and mechanical characteristics and the thermal conductivity of the epoxy–TEOS/MWCNTs composites is investigated. The X-ray diffraction (XRD) analysis reveals that the pure epoxy-TEOS is amorphous, while epoxy–TEOS/MWCNTs composites are crystalline with an orthorhombic crystal structure that has an average crystallite size of 3.9 ± 0.15 nm. In addition, thermal stability and thermal conductivity were improved by adding TEOS and MWCNTs, whereas the exothermic peak temperature decreases compared with pure epoxy-TEOS. Similarly, the hardness Shore-D and tensile strength reach the optimum value at 4 wt% MWCNTs content. The significant improvement in the mechanical and thermal properties of the prepared composites could be attributed to the synergistic effect of MWCNTs and epoxy–TEOS which was emphasized by Fourier transform infrared (FTIR) spectroscopy. Moreover, epoxy-TEOS sample has high optical transmittance (T) within the visible region, but the composites samples are transparent at λ < 800 nm and have a lower value of T. The indirect optical band gap decreases from 3.59 to 2.91 eV with an increase in MWCNTs fractions from 0 to 10 wt%, respectively. However, the glass transition reflects the onset of decomposition temperatures was also considerably increased. The acquired outcomes such as a large increase in thermal conductivity and tensile stress coupled with reduced T make the composites readily applicable for a variety of applications.

Influence of laser power and scanning strategy on residual stress distribution in additively manufactured 316L steel

Residual stress control in the metal components by additive manufacturing (AM) has been a major challenge. To mitigate this challenge, proper selection of AM process parameters is of great importance. In this study, we investigate the influence of laser power and scanning strategies on residual stress distribution in 316L steel by a metal AM process, namely, selective laser melting (SLM). Finite element simulation and experimental verification are conducted by using the identical process parameters and part geometry to ensure that the results are indeed comparable and can shed light on the challenging issue of residual stress control. With two levels of laser power (i.e., 160 W and 200 W) and two scanning strategies (i.e., stripe scanning and chessboard scanning), four process conditions are investigated. For all four conditions, both simulation and experiment show that the tensile residual stress in the area of interest (the center area of each layer) tends to gradually increase along the depth into surface. Also, the increase of laser power from 160 W to 200 W and the adoption of stripe scanning (instead of chessboard scanning) generally lead to the increase of tensile residual stress in the area of interest. The trends are also confirmed by both simulation and experiment. In addition, the laser power increase from 160 W to 200 W appears to have more significant effect, compared with the switch of two scanning strategies.

Study on Mechanical Properties of Main Girder of Continuous Box Girder Bridge Strengthened By A Cable-Stayed System

The local stress concentration of the main girder during the tensioning construction of the continuous box girder bridge strengthened by the cable-stayed system is more prominent, which may lead to the sudden damage of the structure. Therefore, this paper studies the key section stress and deformation of the main girder in combination with the real bridge test. The results show that the maximum tensile and compressive stress increase of the main girder appears at the root floor and midspan floor; The tensile action strengthens the compressive stress between the anchorage point of the long cable and the anchorage point of the short cable to the top of the pier, which releases some of the compressive stress across the mid-slab, improves the stress state of the main girder, and improves the shear load of the main girder ability; With the increase of the cable force, the main tensile stress of the web in the anchoring area first increases and then decreases. The lifting amount of the midspan section of the main girder accounts for 20.06% of the total deflection, and the effect of the cable-stayed system on improving the deflection of the main girder is obvious.

Study of bandgap property of a bilayer membrane-type metamaterial applied on a thin plate

This work is aimed to study the bandgap property of a thin plate structure with periodically attached bilayer membrane-type resonators. An analytical method based on the Plane Wave Expansion (PWE) method combined with the Rayleigh method, is proposed to predict the bandgap property of bilayer membrane-type metamaterials. The accuracy of the proposed method is verified by the finite element analysis, and a parametric analysis is conducted to reveal the effect of parameters on the bandgap performance. It is found that such a metamaterial can generate two separated bandgaps through the contribution of its two layers of membranes. It is observed that the increase of membrane tensile stress or the magnitude of attached mass can lead to the broadening of bandgaps, whilst the change of unit cell's periodicity has the opposite effect. In addition, if compared with the corresponding single layer membrane-type metamaterials, it is shown that the bilayer membrane-type's first bandgap is suppressed while the second one is extended. However, by applying proper membrane tensile stress and mass magnitude, the suppression of the first bandgap can be weakened whilst allowing the tuning of the bandgap location. These characteristics reveal the benefits of using bilayer membrane-type metamaterial as it possesses higher agility in bandgap tuning. The proposed method can provide an effective tool for the bilayer membrane-type metamaterial design and optimisation.

Carbon dots: Fluorescence active, covalently conjugated and strong reinforcing nanofiller for polymer latex

This paper reports a unique approach to the synthesis of rubber nanocomposites in which functionalized carbon dots (cdots) are covalently bonded to functionalized rubber latex. In this approach, the cdots are functionalized with amine (-NH2) groups that are capable of chemically binding with the carboxylated styrene butadiene rubber (XSBR) latex possessing acid (-COOH) groups. Pristine cdots are characterized using powder X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area analysis, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), fluorescence spectroscopy, ultraviolet–visible (UV–Vis) spectroscopy and high resolution transmission electron microscopy (HRTEM). The -COOH groups of XSBR latex has been covalently appended with the -NH2 groups of cdots using N-hydroxysuccinimide (NHS) and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (EDC) mediated amide coupling. FTIR spectroscopy and XPS endorse the covalent conjugation of cdots with XSBR latex. Remarkable increase in the maximum tensile stress and elongation at break of XSBR has been observed by addition of very less amount cdots. XSBR containing 0.8 parts per hundred of rubber (phr) of cdots shows a maximum tensile stress value which is around 235% higher in comparison to neat XSBR. Dynamic mechanical analysis (DMA) shows the reduction in the tan δ peak height and increase in the tan δ peak temperature of XSBR by incorporation of cdots. Also, XSBR containing 0.8 phr of cdots shows an elastic modulus (E’) value which is around 70% higher in comparison to neat XSBR. The maximum degradation temperature (Tmax) and the onset of degradation temperature (Ti) of XSBR containing 1 phr of cdots is around 10 °C and 8 °C higher when compared to neat XSBR. The prominent improvement in the overall properties of XSBR latex by addition of cdots has been attributed to the enhanced cross-linking introduced by the covalently conjugated cdots in XSBR matrix. XSBR-cdots nanocomposite has also been found display good photoluminescence properties due to the presence of cdots, which are confirmed by UV–Vis spectroscopy and fluorescence spectroscopy studies. Morphology of XSBR-cdots nanocomposites has been studied using HRTEM and atomic force microscopy (AFM).

Fatigue properties of titanium alloy custom short stems fabricated by electron beam melting

The fatigue properties of titanium alloy short-stems with four different lengths, manufactured by electron beam melting (EBM) technology, were investigated by in vitro test and finite element (FE) analysis. FE simulation results indicate that the maximum tensile stress concentrates at the lateral side of the stem body. The magnitude of the concentrated tensile stress increases and the corresponding area of the axial section decreases with increasing of stem length. Results from fatigue tests demonstrate that fatigue cracks mainly initiate from the rough surface of the stem where the maximum tensile stress concentrates. The fatigue strength decreases with the increase of stem length, which is attributed to the higher stress concentration on the longer stem surface. In addition, it is found that post EBM treatment via hot isostatic processing (HIP) is able to enhance the fatigue properties of the stems, since the pores generated during EBM are mostly closed during HIP. Our work also demonstrates that the stress concentration on the stem surface can be effectively mitigated and the corresponding fatigue properties of the EBM-fabricated titanium alloy short stem can be considerably improved by optimizing the design in the stem length.

Influence of silicon content on mechanical properties of IADI obtained from as cast microstructures

ABSTRACT This study investigates the mechanical properties of Intercritically Austempered Ductile Iron (IADI) obtained after the heat treatment of ductile irons having different as-cast microstructures and Si concentrations. Tensile strength, impact strength and hardness are measured. The results show that it is possible to obtain acceptable IADI microstructures starting from different as cast microstructures, obtaining similar mechanical properties than those obtained starting from fully ferritic matrices. Tensile strength, yield stress and hardness increase when the silicon content in the melt increases and with the amount of ausferrite present in the microstructure. Particularly, IADI achieved on 3.1% Si DI showing approximately 50% of ferrite and 50% of ausferrite have the best combination of mechanical properties. The IADI samples obtained using different chemical compositions and heat treatment parameters allowed to satisfy every grade specified in ASTM A536 standard for ductile iron showing improved elongation at failure.

Stress evaluation induced by wiggling silicon nitride fine pattern using Raman spectroscopy

We evaluated the residual stress of the silicon nitride (SiN) fine pattern structure in order to quantitatively predict the occurrence of wiggling, which causes device failure. UV Raman spectroscopy showed an increase of tensile stress in Si substrate with increasing etching time, and the tensile stress in Si substrate was caused by the enhancement at the very edge of the fine pattern and the increase in the amount of over-etching. It was also confirmed that the edge enhanced effect can be obtained by using a UV laser for fine patterns, so that the Raman intensity from Si (amorphous and crystal) increased significantly with the etching time of the pattern. Furthermore, using water-immersion Raman spectroscopy, we evaluated the anisotropic biaxial stress applied to the fine patterns and showed occurrence of strain relaxation. The wiggling, therefore, occurs due to the huge anisotropic stresses induced in the Si substrates.

Numerical investigation of micro-cracking behavior of brittle rock containing a pore-like flaw under uniaxial compression

Pore-like flaws, which are commonly encountered in brittle rock, play an important role in the engineering performance of structures constructed in or on rock. Experimental and numerical investigations of micro-cracking mechanism of rock containing a pore-like flaw can enhance our knowledge of rock damage/failure from a microscopic view. In this study, the influences of a two-dimensional circular pore-like flaw with respect to its diameter and position on the strength and micro-cracking behavior of brittle rock under uniaxial compression are numerically investigated. The results reveal that the strength and elastic modulus are significantly affected by the diameter and position in the pore. The uniaxial compressive strength and elastic modulus of the numerical model with a pore diameter of 15.44 mm located in the center of the model are found to decrease by 58.6% and 56.4% respectively when compared with those of the intact model without a pore. As the pore position varies while the porosity remains unchanged, the simulated uniaxial compressive strength and elastic modulus are also found to be generally smaller than those of the intact model without a pore. When a pore-containing numerical model is loaded, the micro-cracks are found to mostly initiate at the top and bottom of the pore, due to the local tensile stress increase. The simulation results of the early-stage micro-cracking process and stress distribution are in a generally good agreement with the analytical solution obtained from the Kirsch equations. The grain-based model used in this study can not only study the crack initiation on the boundary of the pore but also provide a convenient means to analyze and visualize the temporal and spatial micro-cracking process after the crack initiation, which accounts for the variations in the simulated strength and modulus satisfactorily from a micro-cracking view.

The Dynamic Mechanical Properties for Recycled Aggregate Concrete under Tensile-Compressive States

The experiments under biaxial tensile-compressive (T-C) complex stress were carried out for two kinds of substitution percentages of recycled coarse aggregate (RCA) on biaxial proportional loading (α = σ1:σ3 =1:0, 0: −1, 0.05: −1, 0.1: −1, 0.25: −1, 0.5: −1, 1: −1 and−1: −1) and four loading deformation rates of 10−5/s, 10−4/s, 10−3/s, and 10−2/s. The research was completed in the static-dynamic true triaxial machine. The experimental phenomena indicate the tensile failure appears in these specimens of recycled aggregate concrete (RAC) under biaxial T-C stress states. The dynamic mechanical behavior for RAC under biaxial T-C loadings was affected by the strain rates, stress ratios and its substitution percentages of RCA. Accompanied by the increase of strain rates, its strength of RAC is improved. As the tensile stress increases, its compressive strength decreases. The T-C strengths for RAC under biaxial T-C states are less than its corresponding uniaxial T-C strengths at a certain identical strain rates, respectively. Considering the effect of loading rates, a new tensile-compressive failure criterion is established under complex stress states.

Effect of tensile stress on the hydrogen permeation of MS X65 pipeline steel under sulfide films

The effect of the tensile stress on the hydrogen permeation of MS X65 pipeline with sulfide films was investigated through measuring the steady-state hydrogen permeation current (I∞), permeability (J∞L) and apparent diffusivity (Dapp) and quantitatively analysing the hydrogen-permeable resistance factor (HPRF) of single tensile stress HPRF (stress), single sulfide film HPRF (film) and the two together HPRF (stress-film). The results indicated that J∞L and sub-surface hydrogen concentration (co) greatly increase and that Dapp decreases as the elastic stress increases. When applying plastic stress, J∞L and Dapp all reduce, while co continues to increase without the film but decreases with the film. While single tensile stress can promote hydrogen permeation, with the sulfide film, the value of HPRE (stress-film) is not a simple addition of the value of the HPRE (stress) and the HPRE (film), and the interaction results in the blocking effect of hydrogen permeation. The surface morphology of the sulfide films changes caused by tensile stress should be responsible for the HPRE (stress-film) reducing as tensile stress increases but increasing with plastic tensile stress.

Hygrothermal Creep and Stress Redistribution Analysis of Temperature and Moisture Dependent Magneto-Electro-Elastic Hollow Sphere

In this article, the time-dependent stress redistribution analysis of magneto-electro-elastic (MEE) thick-walled sphere subjected to mechanical, electrical, magnetic and uniform temperature gradient as well as moisture concentration gradient is presented. Combining constitutive equations of MEE with stress-strain relations as well as strain-displacement relations results in obtaining a differential equation in which there are the creep strains. At the first step, discounting creep strains in the mentioned equation, an analytical solution for the hygro-thermo-magneto-electro-elastic behavior is achieved at the initial state. After that, the creep stress rates can be achieved by keeping only the creep strains in the differential equation for the steady-state condition. The analysis is done by applying the Prandtl-Reuss equations as well as Norton’s law in creep behavior modeling. Finally, the history of stresses, displacement as well as magnetic and potential field, at any time, is achieved using an iterative method. Results show that the increase in tensile hoop stress resulted from creep progress must be considered in design progress. Also, the effect of hygrothermal loading is more extensive after creep evolution.

Microstructure, Oxidation Resistance and Mechanical Properties of Nb–Y–N Films by Reactive Magnetron Sputtering

Composite Nb–Y–N films with different yttrium content (Y/(Nb + Y), at %) were prepared by reactive magnetron sputtering and the microstructure, oxidation resistance and mechanical properties were investigated. A combination of X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM) analyses showed that the face-centered cubic (fcc) Nb–Y–N and hexagonal close-packed (hcp) Nb–Y–N coexisted in Nb–Y–N films. The adjunction of Y into NbN matrix led to a first increase in the hardness and then a subsequent decrease after reaching a summit with the value of ~31 GPa at 9.4 at % Y. The first increase of the hardness may be caused by the solid solution hardening and the increase of grain coarsening and tensile residual stress result in the succedent decrease of hardness. The oxidation resistance temperature of Nb-Y-N films increased gradually from about 500°C to about 760°C as the Y content in the film increases from 0 to 12.1 at %.

Preparation of biodegradable PLA/PCL composite filaments: effect of PLA content on strength

As one of the predominant 3D additive manufacturing technology, fused deposition modeling (FDM) suffers from the rich printable filaments. The goal of this paper is to produce a fully biodegradable polymeric composite filament by blending polylactic acid (PLA) with polycaprolactone (PCL). The effect of PCL content on the geometry, size, roughness and ultimate tensile stress of PLA/PCL composite filaments was investigated, and mechanical properties of the printed components were tested. The results indicate that, with the increase of PCL content, the diameter and ultimate tensile stress gradually decreased, while the surface roughness gradually increased. Due to the toughing effect, with an increase in PCL content, the tensile strength of parts decreased, while the elongation at break and the impact strength kept rising. It was found the parts printed with the addition of 20% of PCL composite filament exhibits the optimal comprehensive performance.