Bending Strength Measurements Research Articles

The effect of testing rate on biomechanical measurements related to stalk lodging

BackgroundStalk lodging (the premature breaking of plant stalks or stems prior to harvest) is a persistent agricultural problem that causes billions of dollars in lost yield every year. Three-point bending tests, and rind puncture tests are common biomechanical measurements utilized to investigate crops susceptibility to lodging. However, the effect of testing rate on these biomechanical measurements is not well understood. In general, biological specimens (including plant stems) are well known to exhibit viscoelastic mechanical properties, thus their mechanical response is dependent upon the rate at which they are deflected. However, there is very little information in the literature regarding the effect of testing rate (aka displacement rate) on flexural stiffness, bending strength and rind puncture measurements of plant stems.ResultsFully mature and senesced maize stems and wheat stems were tested in three-point bending at various rates. Maize stems were also subjected to rind penetration tests at various rates. Testing rate had a small effect on flexural stiffness and bending strength calculations obtained from three-point bending tests. Rind puncture measurements exhibited strong rate dependent effects. As puncture rate increased, puncture force decreased. This was unexpected as viscoelastic materials typically show an increase in resistive force when rate is increased.ConclusionsTesting rate influenced three-point bending test results and rind puncture measurements of fully mature and dry plant stems. In green stems these effects are expected to be even larger. When conducting biomechanical tests of plant stems it is important to utilize consistent span lengths and displacement rates within a study. Ideally samples should be tested at a rate similar to what they would experience in-vivo.

Investigating ultrasonic dispersion of nanostructured silica for nanocomposite materials application

This article presented the results of investigating the influence of ultrasonic dispersion of nanostructured silica that has been referred to nanosilica (n-SiO2) into unsaturated polyester (UPE) resin for nanocomposite materials application. Scanning electron microscopy (SEM) method was employed to analyze the dispersion characteristics in this work. The optimally suitable ultrasonic factors have been identified including ultrasound frequency amplitude of 60%, ultrasound time of 120 minutes. Also, the bending strength measurement results of nanocomposite samples have shown that nanosilica material addition has increased significantly the mechanical properties of the nanocomposite material based on UPE resin. This also has shown the possibility of using n-SiO2 as a reinforcing agent for nanocomposite materials applications.

Preparation of a nano aluminum phosphate enhanced hydroxyapatite coating for marble conservation

Open-air marble relics in Beijing are experiencing degradation due to sugaring, dissolution and other illnesses. Therefore, it is necessary to apply a protective and reinforcing coating to the weathered surface. Hydroxyapatite (HAP) has significantly lower solubility and dissolution rate compared to calcite. Additionally, HAP has similar lattice parameters with calcite, suggesting that a cohesive layer of HAP can be formed over calcite. In fact, HAP exhibits a lattice mismatch of 5 % with calcite, which might potentially lead to stress if the layer exceeds a few nanometre in thickness. On the other hand, aluminum phosphates (ideally, B-AlPO4) only exhibit a 1 % mismatch with calcite and have a solubility lower than that of calcite. In this study, in order to improve the property of HAP in marble conservation, sol–gel method was employed to synthesize nano AlPO4, which were then incorporated into the phosphate solution to produce protective coating on the stone surface. The coatingʼs morphology and the structure were characterized by Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), high capacity 3D X-ray microscopy (XRM), optical microscope, and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS). Moreover, the color, the contact angle, the three-point bending strength measurements, as well as the simulated acid rain test and freeze–thaw treatment were performed to assess the chromatic aberration, hydrophilicity, reliability, and durability of the coating. Results indicated that the nano AlPO4, with its matched lattice parameters and nucleation site provision, facilitated the formation a coherent HAP layer of crystal flakes. Subsequently, the anti‑corrosion property, freeze-thaw resistance and consolidation property of the coating were improved, demonstrating the potential application the hybrid of HAP with nano AlPO4 in the preservation of marble.

Evaluating the strength properties of standing trees through fractometry

In recent years, significant advancements in non-destructive testing (NDT) methodologies have emerged, with applications spanning various domains, including structural wood quality assessment and planted tree characteristic evaluation. Within the context of planted trees, a range of non-destructive and semi-destructive techniques have been developed to assess the extent of degradation in tree trunks. In this study, various mechanical characteristics of brutian pine (Pinus brutia Ten.) trees near the Ertokuş Madrasah in the Atabey district of the province of Isparta are examined. Beside their historical significance, these trees are notable for the potential risk they present in terms of leaning towards the madrasah facade and the risk of falling over. To achieve the goals of research, the resistance characteristics of incremental cores were systematically determined by using a thermal imaging camera in conjunction with a portable, non-destructive testing device called a Fractometer. Totally 15 incremental auger specimens were obtained by extracting three increment core samples, each with a thickness of 5 mm, from the trunks of five distinct trees, all at a consistent height of 1.3 meters above ground level. Bending and compressive strength measurements were recorded at intervals of 6 mm from the core to the outermost layer. Furthermore, the moisture content of the incremental cores was assessed using thermal imaging technology. Following an analysis of the collected data, it was concluded that the mechanical properties of the investigated brutian pine trees within an acceptable range.

Deformation behavior and bending strength of single crystal 8 mol% yttria-stabilized zirconia at microscopic scale

Yield phenomena and bending strength of single crystal 8YSZ were evaluated using microcantilever beam specimens with various crystal orientations. Nonlinearity due to plastic deformation was observed in the stress-strain curves, and the yield stress was found to depend on the crystal orientation. TEM observation revealed many areas of disordered lattice in the region where the maximum tensile stress occurred. Resolved shear stress (RSS) was analyzed for the primary {001}<110> and the secondary {110} <11̅0> and {111} <11̅0> slip systems as a function of the angle between the specimen’s longitudinal direction and the [001] orientation, indicating that the RSS for the secondary ones was the critical RSS in the angle at 10° or lower while that for the primary one did so at 20° or higher. The measured bending strength, which depended on the crystal orientation, was lower than, but on the same order of magnitude as, the ideal strength.

Experimental error analysis of biomechanical phenotyping for stalk lodging resistance in maize

Stalk lodging destroys between 5 and 25% of grain crops annually. Developing crop varieties with improved lodging resistance will reduce the yield gap. Field-phenotyping equipment is critical to develop lodging resistant crop varieties, but current equipment is hindered by measurement error. Relatively little research has been done to identify and rectify sources of measurement error in biomechanical phenotyping platforms. This study specifically investigated sources of error in bending stiffness and bending strength measurements of maize stalks acquired using an in-field phenotyping platform known as the DARLING. Three specific sources of error in bending stiffness and bending strength measurements were evaluated: horizontal device placement, vertical device placement and incorrect recordings of load cell height. Incorrect load cell heights introduced errors as large as 130% in bending stiffness and 50% in bending strength. Results indicated that errors on the order of 15–25% in bending stiffness and 1–10% in bending strength are common in field-based measurements. Improving the design of phenotyping devices and associated operating procedures can mitigate this error. Reducing measurement error in field-phenotyping equipment is crucial for advancing the development of improved, lodging-resistant crop varieties. Findings have important implications for reducing the yield gap.

SiC Nanoparticles Strengthened Alumina Ceramics Prepared by Extrusion Printing

Extrusion-free-form printing of alumina ceramics has the advantages of low cost, short cycle time, and high customization. However, some problems exist, such as the low solid content of ceramic paste and the unsatisfactory mechanical properties of pure alumina ceramics. In this study, SiC nanoparticles were used as a reinforcement phase added to the alumina ceramic matrix. Methylcellulose is used as the binder in the raw material system. Ammonium polyacrylate is used as a dispersant to change the rheological properties of the slurry and increase the solid content of ceramics. SiC nanoparticle-strengthened alumina ceramics were successfully prepared by the extrusion process. The relative settling height and viscosity of ceramic slurries were characterized. The sintering shrinkage of composite ceramics was tested. The flexural strength, fracture toughness, and hardness of the ceramics were characterized. The strengthening and toughening mechanisms of the composite ceramics were further explained by microscopic morphology analysis. Experimental results show that when the content of the dispersant is 1 wt.%, the rheological properties of the slurry are the best. Maximum measured bending strength (227 MPa) and fracture toughness (5.35 MPa·m1/2) were reached by adding 8 wt% SiC nanoparticles; compared with pure alumina ceramics, flexural strength and fracture toughness increased by 42% and 41%, respectively. This study provides a low-cost and effective method for preparing ceramic composite parts.

Preparation and Study of Composite Materials of the NiAl-Cr-Mo-Nanoparticles (ZrO2, MgAl2O4) System.

Materials based on the NiAl-Cr-Mo system with zirconium oxide or aluminum-magnesium spinel nanoparticle small additions were obtained by spark plasma sintering. Thermodynamic modeling was carried out to predict the phase formation in the NiAl-Cr-Mo system and its change depending on temperature, considering the presence of a small amount of carbon in the system. The phase composition and microstructure of materials were studied. NiAl (B2) and CrMo phases were found in the sintered samples. Bending strength measurements at different temperatures shows that nanoparticles of insoluble additives lead to an increase in bending strength, especially at high temperatures. A fractographic analysis of the sample’s fractures shows their hybrid nature and intercrystalline fracture, which is confirmed by the clearly visible matrix grains similar to cleavage. The maximum strength at 700 °C (475 MPa) was found for material with the addition of 0.1 wt.% zirconium oxide nanoparticles. In the study of internal friction, typical peaks of a nickel-aluminum alloy were found in the temperature ranges of 150–200 °C and 350–400 °C.

Investigation of Mechanical Strength and Weight Fraction of Date Palm Fibre Hybrid Composites Reinforced with Polyethylene

Polyethylene, elastomer, and date palm fibre are all readily available, it have an positive impact on growth of new composite materials with desirable features and characteristics. There are many different types of composites, but they all have the same goal: to create a new material with greater qualities than the constituent materials. Date palm fibre was employed to reinforce a composite matrix made of polyethylene (PE) plastic and elastomer. To find out the tensile, impact, and bending strength values of composites by weight fractions of 25% (75:25), 35% (65:35), and 45% (55:45), this research set out to find (55:45). Composites with a weight percentage of 25% (75:25) had less Tensile strength (TS) 1.213 MPa, though mixtures with weightage proportion of 45% (55:45) had the maximum TS of 2.613 MPa. The minimum tensile strain value was discovered in composites with a weight fraction of 25% (75:25), while the maximum tensile strain value was identified in composites with weight fraction of 45 percent (0.0067). (55:45). 45 % (45-55) weight ratio mixture had the minimum impact strength of 45321 kJ/mm2, while the 25 percent (75-25) weight ratio mixture had the maximum impact strength of 17721.41 kJ/mm2. A 25 percent weight fraction (75:25) composite had the lowest bending strength measurement result (1.816 MPa), whereas a 35 percent weight fraction (65:35) composite had the highest measurement result (4.9 MPA) in this category. At 75:25 (75:25), the bending strain of the composite was at its highest, with a value of 0.0216

A review on gradient macroporous ceramic via powder-based direct foaming process

Macroporous ceramics are potentially applicable in a wide range of industrial applications. The porous structure of macroporous ceramics is designed depending on the application of macroporous ceramics. This paper reviews gradient macroporous ceramics fabricated via powder-based direct foaming to produce a relatively dense surface and a highly porous body. The fabrication process and the characterization of such ceramics are also considered. In terms of fabrication, an overview of the direct-foaming and foaming conditions to obtain a uniform porous structure is described. With regard to characterization, the unique structure of porous ceramics and effect of the denser surface on the bending strength are summarized through the results of microstructural observation and three-point bending strength measurements. The presence of the surface layer enables an improvement in the bending strength while maintaining high porosity. The fabrication processes reviewed herein are highly promising for reducing the weight of porous ceramics while enhancing their mechanical strength.

Mechanical reinforcement of 3D printed cordierite-zirconia composites

In this study, composite ceramic slurries based on submicron-micron-sized cordierite-zirconia were prepared with varied zirconia content. Standard bending strength and fracture toughness testing samples were directly designed and fabricated using stereolithography 3D printing followed by different sintering schemes to study the mechanical reinforcement effect. The physical compositions and microstructures of the samples were characterized. The additively manufactured cordierite-zirconia composites exhibit excellent mechanical properties. Maximum measured bending strength (136 MPa) and fracture toughness (1.8 MPa m1/2) were reached by adding 2 wt% and 6 wt% zirconia, namely an increase of 44% and 66% relative to pure cordierite, respectively. The strengthening and toughening mechanisms of the composites were further explained mainly by microstructural analysis. This study provides an alternative and direct design and manufacturing method for the mechanical measurement and reinforcement of ceramic composite parts based on the use of 3D printing technology.

Experimental and Numerical Investigation of PMMA Based Composites used for Bone Cement Application

Polymethylmethacrylate PMMA is considered a generally famous bone cement base material. Most failures that take place during function, are due to its weakness and lack of mechanical resistance. The clear limitations of PMMA are not enough ductility, strength, and viscoelastic behavior. Current research is an attempt to numerically using finite element and experimentally investigate of flexural and compression behaviour of PMMA bone cement strengthen and improve by adding modified TiO2 nanoparticles (m-TiO2 NPs). Therefore, the neat TiO2 nanoparticles were modified by silane coupling agent and then added by different ratios (0.5, 1, 1.5, and 2 wt %) to the PMMA bone cement. Fourier transform infrared spectroscopy (FTIR) technique used to investigate the modification process, as well as to specify the bonding type between the m-TiO2NPs and the PMMA bone cement matrix. (SEM) technique used to study the morphologies of the prepared samples. Properties were measured bending strength, compression strength and modulus of elasticity. Results proved the successes of TiO2NPs modification by silane coupling agent and the absence of any chemical bonding between this modified filler and other PMMA bone cement ingredients. The mechanical properties increased by m-TiO2NPs addition up to 1 wt% ratio then decreased. For the purpose of making sure of the possibility of using the proposed composite materials in the application of bone cement, numerical simulation was used using the ANSYS (16.1) program for the femur model, and the results showed good agreement with the practical results. The morphology and numerical results supported the mechanical properties trends.

Impact of Carbon Foam Cell Sizes on the Microstructure and Properties of Pressure Infiltrated Magnesium Matrix Composites.

Magnesium-based composites reinforced with open-celled carbon foams (Cof) of porosity approx. 97 vol % and three cell sizes (20, 45 and 100 ppi) were examined to characterize the influence of foam cell size on the microstructure and properties when pure magnesium and two cast alloys AZ31 and RZ5 were used as matrices. All composites were fabricated by pressure infiltration under the same conditions (temperature, pressure, time). For each matrix composition, two main factors due to the presence of the foam determined the composite microstructure—the efficiency of foam penetration and different conditions of metal crystallization. The lowest porosity was obtained when Cof45ppi was used and was independent of the applied matrix composition. The metallic component microhardness increased with a decrease in the carbon cell size as well as a decrease in the α-Mg grain size; both of those results should be taken into account during theoretical calculations. Compression and three-point bending strength measurements showed increases as the carbon cell size decreased, but reinforcing effectiveness relative to the matrix material depended on the metal matrix composition. At the fractured surface, different structural effects in the foam and matrix as well as at the interface were observed and depended on the foam geometry, metal composition and mechanical test type. In glassy carbon foam, those effects occurred as cracking across walls, fragmentation, and delamination, while in the matrix, shear bands and intergranular cracking were observed. On the delaminated foam surface, the microareas of a thin oxide layer were detected as well as dispersed phases characteristic for the applied matrix alloys. The accumulation of intermetallic phases was also observed on the metal matrix surface in microareas delaminated from the carbon foams. Mechanical property results indicated that among the tested, open-celled, carbon foams a 45 ppi porosity was the most useful for pressure infiltration and independent of magnesium-based matrix composition.

Integrated Puncture Score: force\u2013displacement weighted rind penetration tests improve stalk lodging resistance estimations in maize

BackgroundStalk lodging (breaking of agricultural plant stalks prior to harvest) is a multi-billion dollar a year problem. Rind penetration resistance tests have been used by plant scientists and breeders to estimate the stalk lodging resistance of maize for nearly a hundred years. However, the rind puncture method has two key limitations: (1) the predictive power of the test decreases significantly when measuring elite or pre-commercial hybrids, and (2) using rind penetration measurements as a breeding metric does not necessarily create stronger stalks. In this study, we present a new rind penetration method called the Integrated Puncture Score, which uses a modified rind penetration testing protocol and a physics-based model to provide a robust measure of stalk lodging resistance.ResultsTwo datasets, one with a diverse array of maize hybrids and one with only elite hybrids, were evaluated by comparing traditional rind penetration testing and the Integrated Puncture Score method to measurements of stalk bending strength. When evaluating the diverse set of hybrids, both methods were good predictors of stalk bending strength (R2 values of 0.67). However, when evaluating elite hybrids, the Integrated Puncture Score had an R2 value of 0.74 whereas the traditional method had an R2 value of 0.48. Additionally, the Integrated Puncture Score was able to differentiate between the strongest and weakest hybrids in the elite hybrid data set whereas the traditional rind penetration method was not. Additional experiments revealed strong evidence in favor of the data aggregation steps utilized to compute the Integrated Puncture Score.ConclusionsThis study presents a new method for evaluating rind penetration resistance that highly correlates with stalk bending strength and can possibly be used as a breeding index for assessing stalk lodging resistance. This research lays the foundation required to develop a field-based high-throughput phenotyping device for stalk lodging resistance.

Stalk Bending Strength is Strongly Associated with Maize Stalk Lodging Incidence Across Multiple Environments

Stalk lodging in maize results in substantial yield losses worldwide. These losses could be prevented through genetic improvement. However, breeding efforts and genetics studies are hindered by lack of a robust and economical phenotyping method for assessing stalk lodging resistance. A field-based phenotyping platform that induces failure patterns consistent with natural stalk lodging events and measures stalk bending strength in field-grown plants was recently developed. Here we examine the association between data gathered from this new phenotyping platform with counts of stalk lodging incidence on 47 maize hybrids representing a subset of genetic diversity. For comparative purposes, we examine four additional predictive phenotypes commonly assumed to be related to stalk lodging resistance; namely, rind penetrometer resistance (a.k.a. rind puncture resistance), cellulose, hemicellulose, and lignin. Lodging incidence data were gathered on 47 hybrids, grown in 98 distinct environments, spanning four years and 41 unique geographical locations in North America. Using Bayesian generalized linear mixed effects models, we show that stalk lodging incidence is associated with each of the five predictive phenotypes. Further, based on a joint analysis we demonstrate that, among the phenotypes considered, stalk bending strength measured by the new phenotyping platform is the strongest predictive phenotype of naturally occurring stalk lodging incidence in maize, followed by rind penetrometer resistance and cellulose content. This study demonstrates that field-based measurements of stalk bending strength provide a reliable estimate of stalk lodging incidence. The stalk bending strength data acquired from the new phenotyping platform will be valuable for phenotypic selection in breeding programs and for generating mechanistic insights into the genetic regulation of stalk lodging resistance.

Application of central composite design to the optimization of fly ash-based geopolymers

The geological polymer materials were optimized by the central composite response surface method (CCD-RSM). Based on the results of the Plackett-Burman experiment and the steepest ascent experiment, four factors were selected that mainly affected the bending strengths of the samples: content of Na2SiO3, curing time at 120 °C, curing time at 250 °C, ratio of fly ash to slag. The optimum values of the four variables were as follows: curing time at 120 °C of 2.25 h, curing time at 250 °C of 2.32 h, Na2SiO3 content of 19.52% and a fly ash-to-slag ratio of 8.21. The measured bending strength of the optimized sample was 37.28 MPa. The new formation of needle-like ferrierite-Na observed in the XRD, SEM and FTIR analyses could increase the bending strengths of the samples, whereas trona-syn, which formed from excessive alkali, was detrimental to the bending strengths of the samples.

DARLING: a device for assessing resistance to lodging in grain crops

BackgroundStalk lodging (breakage of plant stems prior to harvest) is a major problem for both farmers and plant breeders. A limiting factor in addressing this problem is the lack of a reliable method for phenotyping stalk strength. Previous methods of phenotyping stalk strength induce failure patterns different from those observed in natural lodging events. This paper describes a new device for field-based phenotyping of stalk strength called “DARLING” (device for assessing resistance to lodging in grains). The DARLING apparatus consists of a vertical arm which is connected to a horizontal footplate by a hinge. The operator places the device next to a stalk, aligns the stalk with a force sensor, steps on the footplate, and then pushes the vertical arm forward until the stalk breaks. Force and rotation are continuously recorded during the test and these quantities are used to calculate two quantities: stalk flexural stiffness and stalk bending strength.ResultsField testing of DARLING was performed at multiple sites. Validation was based upon several factors. First, the device induces the characteristic “crease” or Brazier buckling failure patterns observed in naturally lodged stalks. Second, in agreement with prior research, flexural rigidity values attained using the DARLING apparatus are strongly correlated with bending strength measurements. Third, flexural stiffness and bending strength values obtained with DARLING are in agreement with laboratory-based stiffness and strength values for corn stalks. Finally, a paired specimen experimental design was used to determine that the flexural data obtained with DARLING is in agreement with laboratory-based flexural testing results of the same specimens. DARLING was also deployed in the field to assess phenotyping throughput (# of stalks phenotyped per hour). Over approximately 5000 tests, the average testing rate was found to be 210 stalks/h.ConclusionsThe DARLING apparatus provides a quantitative assessment of stalk strength in a field setting. It induces the same failure patterns observed in natural lodging events. DARLING can also be used to perform non-destructive flexural tests. This technology has many applications, including breeding, genetic studies on stalk strength, longitudinal studies of stalk flexural stiffness, and risk assessment of lodging propensity.

On the rapid manufacturing process of functional 3D printed sand molds

3D printing sand mold technology offers an opportunity for the foundry industry to rethink old casting approaches and to revive the manufacturing approach using computer models. One of the major concerns in sand molding using 3D printing is the functional characterization of the 3D printed molds as its mechanical and mass transport properties. This research paper discusses the effects of binder content on the mechanical strength and the permeability of 3DP sand molds at different curing conditions. The local permeability of the 3DP specimen was measured as a function of the injection flow rate in order to quantify the inertial pressure effects. The mechanical strength of the 3DP sand molds was characterized using traditional three-point bending strength measurements. The results show that the mechanical strength of the printed molds is deeply dependent on the amount of binder and the curing process. The 3PB strength was found to increase when cured at 100 °C and decrease when cured at 200 °C for all binder contents. The 3PB strength attains its maximum when cured at 100 °C for 2 h for all binder content. In contrast, no significant effect of the amount of binder on the initial permeability of the samples before curing was observed within the functional range of binder mass fraction (1.02–1.98 %). Maximum permeability is attained at the same conditions as the 3PB strength. Therefore, the mechanical strength of the sample can be optimized within the investigated range of binder contents without resulting in any significant decrease in permeability.

X-ray tomography of additive-manufactured zirconia: Processing defects – Strength relations

X-ray Computed Tomography (XCT) analysis was applied to identify and quantify typical defects in dense 3Y-TZP zirconia processed by the Lithography-based Ceramic Manufacturing (LCM) technique. XCT derived strengths were anticipated from the XCT data and compared to experimental measurement. A good agreement between XCT data, bending strength measurement and fractographic analysis demonstrates the suitability of X-ray tomography for both defects detection and predictive mechanical strength estimation. It allows also to rank the different defects related to LCM in terms of their criticality versus mechanical resistance.

Graphite-Si-SiC ceramics produced by microwave assisted reactive melt infiltration

A novel microstructure of graphite-Si-SiC ceramics was successfully prepared by liquid silicon infiltration of graphite-based preforms; instead of using conventional methods, the reactive infiltration process was assisted by microwaves. The effects of microwave power variation on the microstructure and the mechanical properties of infiltrated materials were studied. X-ray diffraction and Raman investigations showed the presence of both unreacted graphite and Si in addition to SiC formed at their interface. The graphitic and silicon phases were separated by a SiC network, which results more homogeneous as microwave power was increased. The amount of SiC was found to be higher in function of the growing power level; a higher conversion of graphite into SiC yielded a more dense material. The bending strength measurements confirm this, showing higher values for the samples processed using a power level of 75% of the full power compared to those obtained with 30% and 60%.