Maximum Bending Force Research Articles

Investigation on mechanical properties of hybrid aluminum/composite tubes manufactured by filament winding and hand lay-up

Nowadays, composite tubes have a wide range of applications in industries. Composite tubes are appropriate alternatives for metal energy absorbers. In this investigation, aluminum-composite tubes are made using Filament Winding (FW) and hand lay-up methods. Carbon Fiber (CF) and Glass Fiber (GF) are used in the FW method, and for the hand lay-up method, glass cloth is used. Five samples were fabricated with different stacking sequences, specimens with one, two, and three glass layers, one carbon layer, and hybrid carbon/glass layers. Characterization is performed by Scanning Electron Microscopy (SEM) analysis and mechanical tests (bending, compressive, and fatigue). The maximum bending force in the triple-layer GF tube is higher than other samples, while the maximum compressive force is observed in the hybrid carbon and GF tube. On the other hand, the fatigue strength of single-layer CF tubes is higher than single-layer GF tubes, so that the fracture cycles of single-layer CF tubes (600597) is significantly more than that of single-layer GF tubes (470068) at the force of 35 N. In addition, the compressive and bending energies absorption of samples were calculated. The hybrid carbon and GF tube absorbed higher energy than other samples. In GF and CF hybrid tubes, failure did not occur suddenly but gradually. This appropriate failure mechanism in the hybrid tube resulted in higher energy absorption and made it a suitable choice for industrial applications.

Evaluation of seismic mechanical response of tunnel linings using shaking table tests and numerical analyses

This paper investigates seismically induced circumferential forces and bending moment of tunnel linings using a series of large shaking table tests and numerical analyses. In this regard, a scaled-down tunnel, embedded in two different depths of sandy soil, was tested under different frequencies of input motion. Then, dynamic finite difference analyses, first verified using the results of the performed large scale shaking table tests, were conducted to study the effects of depth ratio (h/a; h: depth of tunnel centerline and a = radius of the tunnel), flexibility ratio (1.2, 10 and 110) and different frequencies of input motion, corresponding to the dimensionless periods (λ/D), on the mechanical behavior of the tunnel lining. The results indicated that, low frequencies of input motions for the tunnel with low flexibility ratio resulted in greater circumferential bending moment values of the tunnel lining. Furthermore, the tunnel depth and adjacent surface foundation intensified the bending moment, shear, and axial forces of the shallow tunnel by about 43 and 17% and did not affect the maximum bending moment and forces locations in the tunnel lining. It is, therefore, necessary to consider the effect of a surface foundation on tunnel lining when constructing shallow subway tunnels in urban areas.

3D PRINTER DESIGN, MANUFACTURING AND EFFECT OF INFILL PATTERNS ON MECHANICAL PROPERTlES

Along with the technological developments, it is an expected situation to discover new developed production methods. Additive manufacturing technologies, such as three-dimensional (3D) printers are one of these methods, allowing direct production of parts with complex geometries that cannot be produced by conventional methods. The most popular and inexpensive method among additive manufacturing technologies is FDM (Fused Deposition Modeling) method. This method is particularly interesting for the manufacture of parts with low production volumes.
 In this study, a 3D-FDM printer with a print volume of 200x200x210 mm has been designed and manufactured.PLA (polylactic acid) test samples having 2 different infill geometries were produced with the 3D printer. Tensile, three-point bending and charpyimpact tests were applied to these samples to investigate the effect of inner filling geometry on mechanical properties. The inner filling geometries are in the form of grid and gyroid. According to the results, while the geometry with the tensile force is "grid", while the geometry with the maximum bending force is "gyroid".It was concluded that different inner filling geometries do not have a significant impact on Charpy impact strength.

Deformation Resistance of Palatal Plate Connectors in Removable Partial Dentures

The aim of our study was to evaluate the deformation resistance of two palatal plate type connectors of removable partial dentures and to make a comparison between the reduced palatal plates and the large ones, in terms of bending resistance during function. We tested 10 maxillary class I Kennedy removable partial dentures made for real clinical cases and duplicated their connectors, 5 of each type. A Universal Loading Machine was used to apply a bilateral progressive force to the PM2-M1 area until the samples bended, recording the force value at which the first change occurred. The results were analyzed using the ANOVA method. For the reduced palatal plate group, the minimum bending force value was 1584 N, the maximum bending force value being 2920 N. For the large palatal plate group, the minimum bending force value was 3150 N, the maximum value being 3380 N. Statistical analysis of data using the ANOVA method shows that the results are statistically relevant, with a p value of 0,001031 (p[0,05). The results showed that decreasing the width of the palatal plate can have a significant effect on the deformation resistance of the major connector and can affect its rigidity; in clinical practice, these results can help dentists to use alternative appropriate design methods of increasing the rigidity of reduced palatal plates, in order to protect both the remaining structures and the acrylic components of the dentures during the years of its functioning. Keywords: palatal plate, removable partial denture, deformation resistance

Tensile Mechanical Behaviour of Multi-Polymer Sandwich Structures via Fused Deposition Modelling.

The application of single homogeneous materials produced through the fused deposition modelling (FDM) technology restricts the production of high-level multi-material components. The fabrication of a sandwich-structured specimen with different material combinations using conventional thermoplastics such as poly (lactic acid) (PLA), acrylonitrile butadiene styrene (ABS) and high impact polystyrene (HIPS) through the filament-based extrusion process can demonstrate an improvement on its properties. This paper aims to assess among these materials, the best material sandwich-structured arrangement design, to enhance the mechanical properties of a part and to compare the results with the homogeneous materials selected. The samples were subjected to tensile testing to identify the tensile strength, elongation at break and Young’s modulus of each material combination. The experimental results demonstrate that applying the PLA-ABS-PLA sandwich arrangement leads to the best mechanical properties between these materials. This study enables users to consider sandwich structure designs as an alternative to manufacturing multi-material components using conventional and low-cost materials. Future work will consider the flexural tests to identify the maximum stresses and bending forces under pressure.

Study of Mechanical Properties of Carbon Steel Plate SA-516 Gr. 70 Welded by SAW Using V-Shape Joint Design

Submerged arc welding (SAW) is a fusion type welding and it is considered one of the most important welding types due to its inherent capabilities of high welding speed, high deposition rate, welding large thickness plates owing to its deep penetration characteristic and many other advantages. In this study, the goal was to investigate the effect of welding parameters, namely (welding current and welding speed) as well as the joint design on the mechanical properties (yield stress, bending force on the face of the weldment and hardness of the weld metal. Experiments were conducted employing Design of Expert (DOE) software and Response Surface Methodology (RSM) technique. The experiments were conducted by welding ASME SA-516 Gr. 70 steel plate with dimension (300 mm × 150 mm × 10 mm) depending upon the design matrix developed via the DOE. Results manifested that the optimum process parameters for maximum yield stress, maximum bending force and minimum hardness were at (425 amps) welding current and (35 cm/min) welding speed, where the arc voltage was held constant at (37 volts). The optimum values for the yield stress, bending force and hardness were (474.447 MPa, 36.997 kN and 150 HV), respectively. Finally, it was found that the predicted and experimental results of yield stress, bending force and hardness agree very well according to the ultimate error (1.05%, 1.92%, and 4.25 %), respectively.

Experimental Research on the Bending Characteristics of Glycyrrhiza glabra Stems

HighlightsA quadratic orthogonal rotation combination design was used to test the influences of four factors.The significant influence of each factor was obtained using the analysis of variance method.Interactions of the factors were analyzed using the response surface method.Abstract. To provide a theoretical basis for the design of harvesting and processing machinery for Glycyrrhiza glabra stems and for energy conservation during processing, the bending characteristics of G. glabra stems were studied. The comprehensive influences of four factors (loading position diameter, loading speed, span, and moisture content) on the bending characteristics of G. glabra stems were tested using a quadratic orthogonal rotation combination design. The results indicated that the single factors loading position diameter and span had a significant influence on the bending characteristics of G. glabra stems. In addition, as the loading position diameter increased, the maximum bending force and bending energy of G. glabra stems tended to increase, while the bending stress tended to decrease. As the span increased, the maximum bending force and bending energy of G. glabra stems tended to decrease, while the bending stress tended to increase. As the moisture content increased, the maximum bending force and bending stress of G. glabra stems tended to decrease, while the influence on bending energy was not significant. The loading speed had no influence on the bending characteristics of G. glabra stems. The interaction between loading position diameter and span had a significant influence on the maximum bending force and bending energy, and the interactions between loading position diameter and moisture content and between loading speed and span had a significant influence on the maximum bending stress. This study on the bending characteristics of G. glabra stems can provide a theoretical basis for the design of harvesting and processing equipment and for the pretreatment of G. glabra stems. Keywords: Bending characteristics, Licorice, Loading position, Loading speed, Moisture content, Span.

Bending Strength of Polyester Composites Reinforced with Stitched Random Orientation and Plain Weave Abaca Fiber

This paper discusses the bending strength of Fiber Reinforced Polymer (FRP) composite made from polyester resin matrix and abaca fiber. The abaca fiber was prepared in the form of stitched random orientation and plain weave woven fabric. The abaca FRP composite was produced by using hand-lay-up method with the variation of weight percentage of the fiber. The weight density of the FRP composite was measured to determine the effect of fiber percentage to the weight density of the composite panel. The three points bending test was performed in order to examine the maximum bending force and flexural strength of the abaca FRP composite. The result of the experiment shows that the fiber weight percentage gave significant effect to the weight density and flexural strength of the abaca composite. Furthermore, the comparison between the two types of fiber form shows that the abaca plain weave woven fiber produces higher flexural strength compare to stitched random orientation woven fiber at all levels of fiber contents.

Effect of profile and reinforcing the surface layers on bending behavior of 3D multi-cell spacer weft-knitted composites

3D multi-cell spacer-knitted reinforced composites are composed of knitted layers which are joined together by multiple fabric connecting layers. Despite numerous capabilities, they demonstrate inferior bending performance due to their highly looped construction as well as low fiber volume fraction. Bending characteristics could be enhanced by inserting the warp and weft yarns through the fabric’s surface layers in wale and course directions. This research aims to investigate the role of reinforcing warp and weft yarns and structure profile on bending behavior of the composites produced from 3D multi-cell spacer-knitted fabrics. 3D multi-cell spacer-knitted fabrics were produced with rectangular cross-sectional shape in single- and double-decker profiles on a computerized flat-knitting machine. The surface layers of both 3D multi-cell spacer-knitted fabrics were reinforced by glass straight yarns in course and wale directions. The produced fabrics were used to fabricate thermoset 3D composites using epoxy resin via vacuum-assisted resin-transfer method. Composite samples were subjected to three-point bending load. Statistical analysis revealed that the composite profile and presence of the reinforcing warp and weft yarns affect significantly the flexural properties of 3D-knitted composites. Accordingly, introduction of the reinforcing straight yarns causes an increase in maximum bending force by 75 and 62.5% for single and double-decker structures, respectively. In order to understand how the tensile and compressive stresses are distributed on the 3D-knitted composite structure as well as to predict their mechanical behavior, a macro-mechanical model was created in the ABAQUS software.

Future Balloon-Expandable Stents: High or Low-Strength Materials?

Recent progress in material science allows researchers to use novel materials with enhanced capabilities like optimum biodegradability, higher strength, and flexibility in the design of coronary stents. Considering the wide range of mechanical properties of existing and newfangled materials, finding the influence of variations in mechanical properties of stent materials is critical for developing a practical design. The sensitivity of stent functional characteristics to variations in its material plastic properties is obtained through FEM modeling. Balloon-expandable coronary stent designs: Absorb BVS, and Xience are examined for artificial and commercial polymeric, and metallic materials, respectively. Standard tests including (1) the crimping process followed by stent implantation in an atherosclerotic artery and (2) the three-point bending test, have been simulated according to ASTM standards. In Absorb BVS, materials with higher yield stress than PLLA have similar residual deflection and maximum bending force to PLLA, which is not the case for Xience stent and Co-Cr. Moreover, elevated yield stress significantly reduces stent flexibility only in Xience stent. For both stents, with different degree of influence, an increase in yield or ultimate stress improves stent radial strength and stiffness and reduces arterial stress and plastic strain of stent, which consequently enhances the stent mechanical performance. Contrarily, yield or ultimate stress elevation increases stent recoil which adversely affects stent performance. Using high-strength materials has a double-edged sword effect on the stent performance and existing uncertainty in the precise estimate of stent mechanical properties adversely affects the reliability of numerical models' predictions.

Modeling of Bending Properties of Stainless Steel 304 Sheets Welded by Tungsten Inert Gas Welding Process

In this research, the effects of both current and argon gas pressure on the bending properties of welded joints were studied. Using the possible ranges of welding gas pressures and currents, Tungsten inert gas welding (TIG) of stainless steel (304) sheet was used to obtain their influence on the maximum bending force of the (TIG) welded joints. Design of experiment (DOE) ‘version 10' was used to determine the design matrix of experiments depending on the used levels of the input factors. Response surface methodology (RSM) technique was used to obtain an empirical mathematical model for the maximum bending force as a function of welding parameters (Current and Argon gas pressure). Also, the analysis of variance (ANOVA) was used to verify the adequacy of the resulted model statistically.

Mechanical properties improvement of MIG welding steel sheets using Taguchi method

ABSTRACT Metal inert gas (MIG) welding process employs many applications, such as automobile panels, ejector pins, nozzles, cold headed fasteners and bolts, etc., since all commercially important applicable metals can be welded in all positions with this process via selecting the proper shielding gas, electrode, and welding variables. These applications are almost subjected to bending failure because an unsuitable hardness with poor bending strength may fail the members rapidly. The aim of this research is to study the influence of the metal inert gas (MIG) welding parameters, including current (84, 140 and 196 A), wire feeding speed (5, 7 and 9 m/min) and gas pressure (17, 20 and 23 Kgf/cm2) on the hardness and maximum bending force of steel due to very little investigations in this field. Taguchi method has been used to design the experiments and to make the optimisation by Minitab 16.

Experimental and numerical performance of corrugated fibreboard at different orientations under four‐point bending test

This paper presents experimental work, finite element (FE) model, and analytical solution for predicting the four‐point bending on C‐flute corrugated fibreboard (CFB) when oriented at different angles. The angles of the CFB samples used in this research study were 0° (cross‐machine direction) and 30°, 45°, 60°, and 90° (machine direction). The CFB was assumed as an orthotropic shell element in the FE model and was validated by comparing the bending stiffness, maximum bending force, and failure formation from the experimental test. It was found in the experiment that the 90° sample had the highest bending stiffness with the lowest maximum bending force while the 0° sample had the opposite. An interesting finding was that the 30° and 45° samples improve the bending stiffness than does 0° without significantly affecting the maximum bending force. Both the FE model and analytical solution predicted the bending stiffness trend of the board from 0° to 90° with good agreement compared with experimental results. The maximum bending force in the FE model showed reasonable agreement with the experimental findings. The failure regions on the samples showed similar patterns in both experiments and the FE model. The accurate response in the FE model justify that it is a good tool to predict the bending behaviour of CFB.

Friction Stir Welding of Low-Carbon Shipbuilding Steel Plates: Microstructure, Mechanical Properties, and Corrosion Behavior

In this study, low-carbon steel plates (ASTM 131A) used generally in shipbuilding applications were joined by friction stir welding (FSW) using optimum processing parameters. The microstructure, mechanical properties, formability, and corrosion behavior of the joint were investigated. From the results of the investigation, it was discovered that two distinct regions, stir zone (SZ) and heat-affected zone (HAZ), were formed in the welded region during FSW of the plates. FSW decreased the ferritic grain size of the SZ from 25 µm to about 4 µm. Refined grains were separated mostly by a high angle of misorientation with the low amount of dislocations. The hardness of the SZ increased from 140 Hv0.3 to about 230 Hv0.3. The yield and tensile strength values of the SZ increased from 256 and 435 MPa to about 457 and 585 MPa, respectively, by the effect of FSW without a considerable decrease in ductility. FSW did not cause a significant change in the formability of the joint. Displacement at the maximum bending force decreased slightly after FSW from 6.31 mm to about 5.69 mm. Also, corrosion resistance after FSW slightly increased as a result of grain refinement. Current density values were obtained as 3.36 × 10−6 A/cm2 (base material 4.44 × 10−6 A/cm2).

Microstructure, mechanical and biodegradable properties of a Mg–2Zn–1Gd–0.5Zr alloy with different solution treatments

Solution treatment is a useful way to improve the degradation resistance of Mg alloys. In this work, effects of solution treatment temperature on mechanical and biodegradable properties of an extruded Mg–2Zn–1Gd–0.5Zr alloy were studied. Microstructure analysis, tensile test, three-point bending test, immersion test and electrochemical test were performed. The results showed that increasing solution temperature decreases the mechanical properties of the alloy. However, three-point bending test revealed that the solution-treated alloy at 510 °C could maintain 95% of its maximum bending force (Fmax) during the 28-day immersion period. After treatment at 510 °C for 5 h, all the second phases were dissolved into the alloy, the galvanic corrosion was inhibited, and the alloy exhibited good corrosion resistance with a corrosion rate of 0.35 mm·year−1 in Hank’s solution.

Effect of Black Tea Extract and Thearubigins on Osteoporosis in Rats and Osteoclast Formation in vitro.

Background: Osteoporosis is a major health problem that is closely related to substantial morbidity, mortality and decline in life quality for the aging population. Although previous studies and epidemiological evidence have demonstrated an association between black tea consumption and the prevention of bone loss, the underlying mechanism remains unclear. So, the effect of black tea extract (BTE) and thearubigins (TRs) on osteoporosis in rats and osteoclast formation in vitro were investigated.Methods: In vivo, ovariectomized (OVX) rats were used to establish osteoporosis models. To validate the model and study the effects of BTE and TRs on osteoporosis, the female Wistar rats were divided into a sham-operated group and five OVX groups including model, Xian-Ling-Gu-Bao (XLGB) (as a positive control), BTE, TRs low-dose, and TRs high-dose group. The rats in the four treatment groups were given the corresponding test sample for 12 weeks. Then, the body weight, femur indices, and serum biomarkers were examined and analyzed. In vitro, RAW264.7 murine macrophages were used as model of osteoclast formation. The effects of BTE and TRs on osteoclasts formation and the specific genes and protein levels of osteoclasts were determined.Results: Although there was no significant effect on the OVX-induced body weight gain by BTE or TRs, the levels of maximum bending force, cortical bone thickness and biomarker of bone resorption (acid phosphatase) can be significantly ameliorated by BTE or TRs in OVX rats. Furthermore, both of BTE and TRs can inhibit the osteoclastogenesis and diminish the expression levels of the related genes and proteins.

Effect of Repeated Sterilization by Different Methods on Strength of Carbon Fiber Rods Used in External Fixator Systems.

We aimed to study the effects of repeated sterilization, using different methods, on the carbon fiber rods of external fixator systems. We used a randomized set of 44 unused, unsterilized, and identical carbon fiber rods (11 × 200 mm), randomly assigned to 2 groups: unsterilized (4 rods) and sterilized (40 rods). The sterilized rods were divided into 2 groups, those sterilized in an autoclave and those sterilized using hydrogen peroxide. These were further divided into 5 subgroups based on the number of sterilization repetition to which the fibers were subjected (25, 50, 75, 100, and 200). A bending test was conducted to measure the maximum bending force, maximum deflection, flexural strength, maximum bending moment and bending rigidity. We also measured the surface roughness of the rods. An increase in the number of sterilization repetition led to a decrease in maximum bending force, maximum bending moment, flexural strength, and bending rigidity, but increased maximum deflection and surface roughness (P < 0.01). The effect of the number of sterilization repetition was more prominent in the hydrogen peroxide group. This study revealed that the sterilization method and number of sterilization repetition influence the strength of the carbon fiber rods. Increasing the number of sterilization repetition degrades the strength and roughness of the rods.

Development of SU-8 hollow microneedles on a silicon substrate with microfluidic interconnects for transdermal drug delivery

Hollow microneedle (MN) arrays offer versatility and control to transdermal drug delivery systems where a variety of drugs and their continuous supply are concerned. They may be used as a standalone device or be integrated with the drug reservoir or micropump. An important aspect in this regard is the effective fluidic communication between the reservoir and the MNs on a robust substrate. In a novel attempt of its kind, we present the development hollow SU-8 MNs on a pre-etched silicon wafer having through holes. SU-8 MNs are fabricated by direct laser writing by aligning them on the silicon substrate with microfluidic ports pre-etched by wet chemical etching. Each process step was optimized after a parametric study. The optimized MNs (500–600 µm length, 100 µm outer diameter and 40 µm inner diameter) have an aspect ratio of 5. The MNs have been characterized for mechanical strength and biological insertion tests for their effectiveness in puncturing the skin without breaking. The maximum compressive force and bending forces for the MNs are 0.27 N and 0.022 N per needle, which are higher than the resistive skin penetrating forces. The microfluidic characterizations show the development of hollow MN lumen with a flowrate of around 0.93 µl s−1 at 2 KPa pressure difference at the inlet. The array of 10 × 10 MNs with 500 µm spacing was able to successfully penetrate mice and rat skin without any breakage.

Effects of post-weld heat treatment on the microstructural evolution and mechanical properties of dissimilar friction stir welded AA6061+SiCp/AA6061-O joint

Abstract A research on the microstructure and mechanical properties of the dissimilar joint was carried out so as to understand the effects of post-weld heat treatment (PWHT) on microstructural evolution, microhardness, tensile and flexural properties of the dissimilar friction stir welded (FSWed) joint. The results showed that there is a sufficient and rather complicated material mixing in the nugget zone (NZ). After PWHT, the grains in the joint area except for the NZ demonstrated a grain refinement with more homogeneous and equiaxed grains. Fine and clustered SiC particles in the NZ are confirmed by scanning electron microscope (SEM). In addition, the microhardness values of nugget zones both in as-welded and PWHT condition exhibited a higher Vickers compared to that of AA6061-O. Furthermore, a mean tensile strength of 183.30 MPa that demonstrates a 52.22% increase in tensile strength is also observed in the transverse tensile tests subsequent to PWHT. Considering the three-point bending test results, it is explicit that an increase of 121.96% in the bending extension is obtained as there is no significant increase in maximum bending force after the PWHT.

Design and Scalable Fabrication of Hollow SU-8 Microneedles for Transdermal Drug Delivery

Hollow microneedle arrays have been sustained since last two decades and hold lot of promise as effective, painless, and controlled way of transdermal drug delivery because of the immense variety of drugs they can deliver. Design and simulation are quintessential prior to proceeding with fabrication of microneedles in order to successfully overcome the skin barrier. In this paper, optimization of the design of hollow microneedles has been carried out by theoretical and simulation based studies. Subsequently, microneedles based on the optimized design are fabricated by direct laser writing. The SU-8 microneedles with simple cylindrical structure are able to sustain the skin resistive forces since their yield strength under different loading conditions is higher than the skin forces. The flow in microneedle lumen is laminar with Reynold's number 3.9. The choice of cylindrical microneedle simplifies the fabrication steps greatly. SU-8 microneedles which are 500 μm tall, 100 μm outer diameter, and 40 μm inner diameter were fabricated by direct laser writing. Aspect ratio of 5 has been achieved for these microneedles. The hollow SU-8 microneedles have clearly defined lumen. Their hardness, Young's Modulus and maximum compressive and bending forces are 0.3 GPa, 4.94 GPa, 0.27 N, and 0.022 N, respectively. The microfluidic tests indicate the development of fully hollow microneedle lumen with a flowrate of 0.93 μL/s at 2 KPa inlet pressure drop. The experimental results are in good agreement with the theoretical and simulation based studies. These MNs can puncture mice skin effectively and are not broken after multiple insertions.