Minimum Bending Strength Research Articles

Characteristics of Mechanical Strength and Flexibility of Shallots Leaf

When operating drone sprayer, such as to distribute pesticides, downwash is the major cause of damage on the plants. Therefore, understanding the mechanical properties of plants are important to be able select the proper drone to use. In this research, characteristics of leaf strength and flexibility of two types of shallots were investigated, namely the Batu Ijo and Birma varieties. Research on the characteristics of the strength and flexibility of shallots was carried out from the 3rd to the 8th week for the Batu Ijo and 9 varieties of Birma, 100 samples each week. The strength of the leaf was measured by pulling the leaf until it breaks by attaching a thread to the base of the leaf which is pulled by a force gauge device. Then to measure its flexibility by pulling the top of the leaf with the thread that is pulled until it touches the ground surface. From this research, data on the strength characteristics of the leaves of the Birma variety 29 N that is much stronger than the Batu Ijo variety 8.9 N got obtained. Meanwhile, for the flexural characteristics, the Batu Ijo variety was 5 N with pressure P 0,113 N/cm2 more flexible than the Birma variety 3.3 N with pressure P 0,087 N/cm2. The minimum bending strength of the leaves for the two varieties F is almost the same, where for the Batu Ijo variety F 0.044 N with P 0.005 N/cm2 and for Birma varety F 0.041 N with pressure P 0.009 N/cm2. Based on the characteristics of this minimum bending, it becomes the basis for optimizing the design of the drone sprayer blade.

Effect of different screw speeds on the structure and properties of starch straws

To illustrate the action mechanism of screw speed on the performance of starch-based straws during the extrusion process, starch-based straws at different screw speeds were prepared using a twin-screw extruder and the structures and characteristics were compared. The results indicated that as screw speeds improved from 3 Hz to 13 Hz, the A chain of amylopectin increased from 25.47 % to 28.87 %, and the B3 chain decreased from 6.34 % to 3.47 %. The absorption peak of hydroxyl group shifted from 3296 cm−1 to 3280 cm−1. The relative crystallinity reduced from 13.49 % to 9.89 % and the gelatinization enthalpy decreased from 3.5 J/g to 0.2 J/g. The performance of starch straws did not increase linearly with increasing screw speeds. The starch straw produced at screw speed of 7 Hz had the largest amylose content, the highest gelatinization temperature, the minimum bending strength, and the lowest water absorption rate in hot water (80 °C). Screw speed had a remarkable impact on the mechanical strength, toughness and hydrophobicity of starch-based straws. This study revealed the mechanism of screw speed on the mechanical strength and water resistance of starch straws in the thermoplastic extrusion process and created the theoretical basis for the industrial production of starch-based straws.

Peculiarities of obtaining nanocomposites with organic additives and consolidated nanomaterials with given properties

The work presents the results of the creation of consolidated nanomaterials and composite ceramics using modern methods of consolidation of ceramic materials for the synthesis of powder precursors and specified phases that self-reinforce ceramic matrices. The method of mechanosynthesis and electroconsolidation is used. The results of the use of these trends for the creation of promising composite materials are given. The use of mechanochemical synthesis of β-SiC nanoparticles in nanoreactors, involving the organic-inorganic complex (–CH3)–(SiO2)n and the modification of refractory filler powders and carbon bonds using silicon alkoxide and related gels, has been demonstrated to enable the production of composite materials. These materials are composed of SiC, WC, and ZrO2, exhibiting a minimum bending strength of 650 MPa and crack resistance ranging from 6.5–7.9 MPa m0.5. Furthermore, this method can also produce periclase-carbon materials known for their exceptional resistance to oxidation and slag.

Bending Strength of Magnesium Oxide Board

Magnesium Oxide (MgO) board has been widely used in prefabricated lightweight steelframe wall systems and as the floor board covering component. It is a non-insulating sheathingboard product which consists of sustainable materials with the characteristics of fire resistance,weather-ability, strength, resistance to mold and mildew. Although MgO board has recentlyworldwide used in façade construction but the research data related to the laboratory work such asthe bending strength is still limited. The previous studies on the bending strength of MgO board arebased on various standards such as ASTM, JC688 and British Standard subjected to the productscharacteristics and patterns. Therefore, the bending strength values obtained were inconsistent andnot convincing. Thus, this paper aims to examine the bending strength of MgO board with threedifference thicknesses (6mm, 9 mm and 12 mm) based on BS EN 310:1993 subjected to threepoints bending test. The failure modes during three points bending test was observed and theexperimental results obtained were compared with the theoretical values and others relevantstandards. A total of thirty six specimens with twelve specimens for each thickness in two groupdirections namely longitudinal (length) and transverse (width) direction were tested. The specimenswere prepared based on BS EN 326-1:1994 and BS EN 325:2012. The maximum flexure load of thespecimens was recorded and arithmetic mean bending strength for each thickness was presented.The experimental results showed the tested MgO board was not achieved minimum bendingstrength for load bearing used. It is recommended to be used in non-load bearing façade claddingconstruction.

Effect of Type and Concentration of Nanoclay on the Mechanical and Physicochemical Properties of Bis-GMA/TTEGDMA Dental Resins.

Bis-GMA/TTEGDMA-based resin composites were prepared with two different types of nanoclays: an organically modified laminar clay (Cloisite® 30B, montmorillonite, MMT) and a microfibrous clay (palygorskite, PLG). Their physicochemical and mechanical properties were then determined. Both MMT and PLG nanoclays were added into monomer mixture (1:1 ratio) at different loading levels (0, 2, 4, 6, 8 and 10 wt.%), and the resulting composites were characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA) and mechanical testing (bending and compressive properties). Thermal properties, depth of cure and water absorption were not greatly affected by the type of nanoclay, while the mechanical properties of dental resin composites depended on both the variety and concentration of nanoclay. In this regard, composites containing MMT displayed higher mechanical strength (both flexural and compression) than those resins prepared with PLG due to a poor nanoclay dispersion as revealed by SEM. Solubility of the composites was dependent not only on nanoclay-type but also the mineral concentration. Dental composites fulfilled the minimum depth cure and solubility criteria set by the ISO 4049 standard. In contrast, the minimum bending strength (50 MPa) established by the international standard was only satisfied by the dental resins containing MMT. Based on these results, composites containing either MMT or PLG (at low filler contents) are potentially suitable for use in dental restorative resins, although those prepared with MMT displayed better results.

Investigations on the mechanical strength of enamelled glass

Enamelled glass has been used for many years in architectural applications. It is well known that ceramic frits have a weakening effect on the mechanical strength of thermally toughened glass. This fact is addressed in the relevant European product standards for thermally toughened (with or without heat soak test) and heat strengthened glass. In EN 12150-1 the minimum bending strength of thermally toughened enamelled glass is given with $$\upsigma _\mathrm{bB} = 75 \hbox {N}/\hbox {mm}^{2}$$ and in EN 1863 for heat strengthened glass the value is given with $$\upsigma _\mathrm{bB} = 45 \hbox {N}/\hbox {mm}^{2}$$ . The values are valid independently of the colour tint and the manufacturing process of the enamel coating. As the experimental data for the current values were determined decades ago and the background of these investigations is not available anymore, a recent research project examined influences of glass type, colour tint and the manufacturing process of the enamel by performing four point bending tests according to EN 1288-3. To compare the results with the non enamelled glass types the glass samples were taken from a single float glass batch. The test results show the strength is mainly dependent on the colour scheme, the thickness of the enamel and the temperature sequence of the fusing process itself. In the paper some of the results will be presented especially the influence of different parameters on the mechanical strength. Furthermore the results will be compared with the current values of the minimum bending strength given in the product standards.

English

In this study, the effects of partial replacement of ordinary Portland cement with natural polymers on selected physical and mechanical properties of cement-bonded rattan composites was investigated. Fibrous particles of Laccosperma secundiflorum rattan cane species were mixed with cement mortar at two levels, that is, 2.5 and 5.0%. For experimentation, Portland cement was partially replaced at four levels, first with Cissus populnea gum (0, 10, 20, and 30%) and then natural rubber latex (0, 2.5, 5.0, and 10%). All test specimens were prepared and tested in accordance with ISO 8335 standard. Results obtained showed that the moisture content, density, water absorption, thickness, and bending strength of the composites met the minimum standard requirements, except for samples produced using 30% C. populnea and 5% rattan fibre that fell short of the 9 N/mm2 minimum bending strength requirement. Partial replacement of cement with the two polymers resulted in a general increase in density. Analyses of variance showed that C. populnea gum had a significant effect (p<5%) on water absorption after 24 h of immersion, while natural rubber latex and C. populnea gum had significant effects on thickness swelling at 2 and 24 h of immersion, respectively. Also, C. populnea gum and rattan fibre contents had significant effects on the bending strength of the composites. It was concluded that Portland cement could be partially replaced with up to 20% of C. populnea gum or up to 2.5% of rubber latex in rattan-cement composite manufacture without adverse effects on the basic composite properties tested. Key words: Rattan cane, Cissus populnea, rubber latex, cement, composites.

Properties of orchard pruning and suitability for composite production

Abstract Apple and cherry pruning with red pinewood particles in various proportions were used as the raw material for the experimental particleboard manufacturing in laboratory conditions. The results showed that there were no considerable differences in the main chemical constituents of carbohydrate and lignin content, although there were some differences found for extractives that are considerably higher for both cherry and apple pruning. The mean modulus of rupture values of boards were found to ranged from 12.4 to 18.48 MPa. These indicated that all the boards, except for the board type F (prepared from 100% apple pruning), met the minimum bending strength required in standard for general-purpose particleboards. The modulus of elasticity and internal bond of the experimental particleboards usually decreased as red pinewood particle content decreases in proportion. However, all the boards produced in this study met the minimum modulus of elasticity, internal bond, and surface strength required in standard for general-purpose particleboards. However, the thickness swelling for 24 h was considerably higher than the required in standard value of 14% for all boards.

Quantitative computed tomographic assessment of the effects of 24 months of teriparatide treatment on 3D femoral neck bone distribution, geometry, and bone strength: Results from the EUROFORS study

We studied the changes in bone distribution, geometry, and bone strength based on 3D quantitative computed tomography (QCT) of the femoral neck (FN) in subjects receiving teriparatide (TPTD). Fifty-two postmenopausal women with severe osteoporosis were analyzed. Patients were divided into three subgroups based on their prior treatment with osteoporosis drugs: treatment-naive (Tx-naive; n = 8), pretreated (pre-Tx; n = 12), and pretreated showing an inadequate response to treatment (inad. pre-Tx; n = 32). QCT scans were performed at baseline and after 6, 12, and 24 months of treatment and were analyzed with Mindways QCT-PRO BIT software. Minimum and maximum section modulus, buckling ratio (BR), and cross-sectional area (CSA) were calculated as measurements of bending strength, risk of buckling, and bone apposition, respectively. After 24 months of TPTD treatment, areal and volumetric FN BMD increased significantly by 4.0% and 3.0%, respectively, compared with baseline. Decreases in cortical volumetric BMD occurred in locations not adversely affecting minimum bending strength indicators. Cortical CSA increased by 4.3%, whereas total CSA remained unchanged over the study duration, indicating that endosteal but no periosteal growth was observed. Strength parameters for buckling did not change at 6 and 12 months but improved significantly at 24 months. Measures of bending strength showed a trend toward improvement. Changes tended to be larger in individuals at higher risk of buckling failure. Prior antiresorptive treatment may delay response to TPTD, but based on the small magnitude of the mostly insignificant changes at 6 months, this does not appear to lead to an interim phase of reduced bone strength. In summary, FN QCT provides a tool for detailed longitudinal investigation of bone strength indices in vivo for different loading modes, yields insight into underlying structural changes, and provides relevant mechanostructural information beyond dual-energy X-ray absorptiometry. Continuous TPTD treatment for 24 months improves FN bone strength parameters.

半溶融成形法による比較的厚いAZ91D合金製平板の相対密度と曲げ強度に及ぼす溶湯温度とゲート流速の影響

AZ91D plates of 5mm in thickness are made by semi-solid molding process, and its relative density and bending strength are investigated under various barrel temperature and gate velocity conditions. The results are as follows. In cases that the plates are made by semi-solid molding process, the relative density can be expressed as a function of the apparent Reynolds number that considers the influence of the solid fraction. At a given apparent Reynolds number, semi-solid molding process can achieve a larger relative density than conventional completely melted process; and the difference of the relative density between these two processes increases as the apparent Reynolds number increases. The bending strength increases as the apparent Reynolds number increases, however it decreases when the decrease of the relative density becomes remarkable. The difference between the maximum and the minimum bending strength of five trials at a given molding condition becomes remarkable when the apparent Reynolds number exceeds a certain value. Therefore, there exists an optimum apparent Reynolds number that can achieve a high strength stably. It is also found that a lower barrel temperature condition is required to obtain both higher relative density and greater bending strength.

Effect of crack-healing and proof-testing procedures on fatigue strength and reliability of Si3N4/SiC composites

Abstract A Si3N4/SiC composite was hot-pressed. Using this material, fatigue tests on crack-healed and proof-tested specimens were conducted at 1000–1400 °C. A surface elliptical-crack of about 110 μm in diameter was introduced on the specimens using a Vickers hardness indenter. The crack-healing was performed at 1300 °C for 1 h in air, mainly. The fatigue limit of the crack-healed and proof-tested specimen (C.P specimen) decreased slightly with increasing test temperature. However, the crack-healed specimen is not sensitive to low-cycle fatigue up to 1400 °C, and the fatigue limit is almost equal to the minimum bending strength at each temperature. To investigate the reason, the crack-healing behavior under cyclic stress was carried out systematically at 1200 °C in air. A 110 μm surface crack could be healed perfectly at 1200 °C in air under cyclic stress with a frequency of 0.001–5 Hz. From this, it can be concluded that [crack-healing+proof test] and crack-healing during service are useful techniques for maintaining structural integrity of these ceramic components.

Characterization of bone cements prepared with functionalized methacrylates and hydroxyapatite

Bone cements prepared with methyl methacrylate and either methacrylic acid or diethyl amino ethyl methacrylate as comonomers were characterized by infrared spectroscopy, nuclear magnetic resonance, gel permeation chromatography, dynamic mechanical thermal analysis, and mechanical testing. Selected formulations containing these functionalized methacrylates were filled with hydroxyapatite and studied in terms of their properties in tension, compression and bending, and X-ray diffraction. It was found that residual monomer was not greatly affected by the presence of either acid or basic comonomers in the unfilled bone cements. In contrast, molecular weight, curing times, and glass transition temperature were composition dependent. For samples with acidic comonomer, a faster curing time, higher molecular weight, and higher glass transition temperatures were observed with respect to those with the basic comonomer. X-ray diffraction revealed that the crystalline structure was not affected by the nature of comonomer in the bone cement while scanning electron microscopy showed that hydroxyapatite remained as clusters in the bone cement.The mechanical properties of filled bone cements depended mainly on composition and type of testing. Hydroxyapatite-filled bone cements fullfilled the minimum compressive strength (70 MPa) required for bone cement use. However, the minimum tensile strength (30 MPa) was only fullfilled by cements prepared without comonomer and those containing methacrylic acid. The minimum bending strength requirement (50 MPa) was not satisfied by any of the formulations studied.

Second metacarpal midshaft geometry in an historic cemetery sample.

Study of bone mass at the second metacarpal midshaft has contributed to our understanding of skeletal growth and aging within and between populations and has relied extensively on noninvasive techniques and in particular radiogrammetric data. This study reports age, sex, and side variation in size and shape data acquired from direct measurement of cross-sections obtained from a large (n = 356), homogeneous skeletal sample. Correlation analysis and three-way ANOVA of size-adjusted data confirm general impressions of patterned variation in this element: males have absolutely but not necessarily relatively larger bones than females; the right side is larger than the left, though a larger than expected proportion (approximately 25%) of left metacarpals exhibits greater values than the right; and bone mass but not strength (in males) declines with age. Contrary to the widely accepted assumption of circularity for this location, direct measurement of cross-sectional geometry confirms previous biplanar radiogrammetric conclusions regarding the noncircularity of the second metacarpal midshaft and identifies a significant difference between males and females, with the latter having a more cylindrical diaphysis. Deviation of the axes of maximum and minimum bending strength associated with noncircularity suggests a distribution of bone mass to resist bending moments perpendicular to the distal palmar arch, though this conclusion awaits more robust study of the functional anatomy of the metacarpal diaphysis.

Second metacarpal midshaft geometry in an historic cemetery sample

Study of bone mass at the second metacarpal midshaft has contributed to our understanding of skeletal growth and aging within and between populations and has relied extensively on noninvasive techniques and in particular radiogrammetric data. This study reports age, sex, and side variation in size and shape data acquired from direct measurement of cross-sections obtained from a large (n = 356), homogeneous skeletal sample. Correlation analysis and three-way ANOVA of size-adjusted data confirm general impressions of patterned variation in this element: males have absolutely but not necessarily relatively larger bones than females; the right side is larger than the left, though a larger than expected proportion (approximately 25%) of left metacarpals exhibits greater values than the right; and bone mass but not strength (in males) declines with age. Contrary to the widely accepted assumption of circularity for this location, direct measurement of cross-sectional geometry confirms previous biplanar radiogrammetric conclusions regarding the noncircularity of the second metacarpal midshaft and identifies a significant difference between males and females, with the latter having a more cylindrical diaphysis. Deviation of the axes of maximum and minimum bending strength associated with noncircularity suggests a distribution of bone mass to resist bending moments perpendicular to the distal palmar arch, though this conclusion awaits more robust study of the functional anatomy of the metacarpal diaphysis. Am J Phys Anthropol 106:157–167, 1998. © 1998 Wiley-Liss, Inc.

An optimum reinforcement solution for a torsionless grillage with given minimum strength

The paper presents the minimum reinforcement solution for a simply-supported square torsionless grillage, with beams parallel to the sides of the square, for specified uniformly distributed transverse load at collapse, for the case where a minimum proportion of reinforcement (and therefore a minimum bending strength) must be provided at every point. The optimal design collapses in a mode satisfying certain conditions on curvature, and the corresponding moment field is developed using lines of load transfer (with finite jumps in moment) for concentrated forces, and the equation of bimoments for finite grillage segments. A solution is obtained only for a limited range of load magnitudes (up to about twice what may be carried with the specified minimum bending strength alone). However, the minimum volume of reinforcement is not much less than that for a simple practical design, with crossed uniform bands of extra reinforcement near midspan, which can cope with any magnitude of load.