New measurement method for bending loss factor and the bending stiffness: Test method

Locking plate technologies are being developed in order to provide the surgeon with advantages over previous bone plate systems (both locking and non-locking). Locking plate systems possess inherent biological advantages in fracture fixation by preserving the periosteal blood supply, serving as internal fixators. It is important to consider the strength of each orthopaedic implant as an important selection criterion while utilizing the reported advantages of locking plate systems to prevent catastrophic fracture failure. Mechanical testing of orthopaedic implants is a common method used to provide a surgeon with insight on mechanical capabilities, as well as to form a standardized method of plate comparison. The purpose of this study was to demonstrate and to quantify observed differences in the bending strength between the LCP (Limited Contact Plate), LC-DCP, 3.5 mm Broad LC-DCP (Limited Contact Dynamic Compression Plate), and SOP (String of Pearls) orthopaedic bone plates. The study design followed the ASTM standard test method for static bending properties of metallic bone plates, which is designed to measure mechanical properties of bone plates subjected to bending, the most common loading encountered in vivo. Single cycle four point bending was performed on each orthopaedic implant. The area moment of inertia, bending stiffness, bending strength, and bending structural stiffness were calculated for each implant. The results of this study demonstrated significant differences (p<0.001) in bending strength and stiffness between the four orthopaedic implants (3.5 Broad LC-DCP>SOP>LCP=LC-DCP). The 3.5 mm LCP should be expected to provide in vivo strength and stiffness similar to a comparable LC-DCP. The SOP should provide strength and stiffness that is greater than a comparable LC-DCP but less than a 3.5 mm Broad LC-DCP.

The bending properties of cardboard in the machine direction and cross direction were obtained via three-point bending and elastica bending tests using samples of various span lengths. The bending stiffness, moment at the proportional limit, and moment capacity per unit width were determined, and the effects of the testing method and span length were investigated. In the three-point bending test, the bending stiffness often decreased as the span length decreased because of the effect of the low interlaminar shear modulus of cardboard, and this tendency was more pronounced when the length direction of the sample coincided with the machine direction. Such dependence was less obvious in the moment at the proportional limit. In contrast, when the length coincided with the cross direction, the moment capacity of the cardboard often decreased as the span length increased because the large deflection prevented the accurate calculation of the moment capacity by using elementary beam theory. However, in the elastica bending test, both the bending stiffness and moment capacity could be obtained while reducing the effect of the span length. Therefore, to obtain the bending properties of cardboard, the elastica bending test was determined to be more advantageous than the three-point bending test.

Modern architecture suggests the use of opened spaces with large transparent envelope surfaces. Therefore, windows of long widths and large heights are needed. In order to withstand the wind loads, such wooden windows can be reinforced with stiffer materials, such as aluminium (Al), glass-fibre reinforced polymer (GFRP), and carbon-fibre reinforced polymer (CFRP). The bending stiffness, load-bearing capacity, and flexural rigidity of hybrid beams, reinforced with aluminium, were compared through experimental analysis, using a four-point bending tests method, with those of reference wooden beams. The largest increases in bending stiffness (29%–39%), load-bearing capacity (33%–45%), and flexural rigidity (43%–50%) were observed in the case of the hybrid beams, with the highest percentage of reinforcements (12.9%—six reinforcements in their tensile and six reinforcements in their compressive zone). The results of the experiments confirmed the high potential of using hybrid beams to produce large wooden windows, for different wind zones, worldwide.

In this paper a novel direct method for mechanical testing of single fibers and fiber joints is presented. Additional to the measurement of joint strength it is also possible to investigate loading geometry, deformation during testing, bending stiffness of fibers as well as bonding energy. Furthermore biaxial loading of fiber-fiber joints is possible. Initial experiments have shown that mode II and III shear strength of fiber-fiber joints can be measured with this setup. Initial results for fibers and fiber joints of unbleached softwood kraft pulp are presented. The resulting values are 1.1724·10-9to 3.8798·10-11Nm² for bending stiffness, 3.9180·10-10to 2.8793·10-11kJ/bond for bonding energy, 6.54 mN for mode II and 1.057 mN for mode III mean shear strength. Mode II mean shear strength under biaxial load with a preload of 20 mN perpendicular to the loading direction of the fiber-fiber joint was found to be 2.52 mN. These values are compared to results of other measurement techniques and discussed.

Wave propagation in and sound transmission through sandwich plates

The author, in continuing the previous study (This Journal, 1938, Vol. 38, No. 584, p. 397-p. 403), studied further on the autoclave test for soundness and expansion or contraction of cement or cement-sand mortar. This testing method was applied on various kinds of Portland cement and mixed Portland cement for various purposes, i.e., (1) Testing expansion or contraction, (2) Bending strength, and (3) Compressive strength from the same test pieces by using 4×4×16cm prismatic test pieces of plastic mortar, which results are briefly abstracted from the original Japanese communication, as following:(1) Cement samples were selected for studying on the value of autoclave test, especially for testing on the relation between the soundness and chemical compositions of various cements. Three samples of common Portland cement, three of low-heat or modified Portland cement, three of high iron oxide Portland cement, one of blast furnace cement, and five of high silica mixed Portland cement, so that totally fifteen samples of various kinds of cement were selected for the present study.(2) These cement samples were first compared their chemical compsiotions and various physical properties. The strength tests were also carried out in two ways, (1) the dry or non-plastic mortar of 1:3-cement and standard sand for Portland and blast furnace cements (JES 28 and 29) of Japanese Engineering Standards, and (2) the wet or plastic mortar of 1:2-or 1:1-cement and fine sand.(3) Beam test pieces (4×4×16cm) ot wet of plastic 1:2-cement and fine sand mortar were treated, after seven days common water curing, in hot water under steam pressure (5kg/cm2 and about 152-153°C or 30kg/cm2 and about 227-228°C) in autoclave for two hours, and measured the expansion or contraction after cooling in water of room temperature and atmosperi pressure. The results were sufficient to make clear the differences between various cements, especially the unsoundness of high iron oxide containing special Portlant and soundness of high silica containing mixed Portland cement by mixing about 30% of proper admixture containing large amount of soluble silica.(4) After this measurement of expansion, the beam test pieces were tested on their bending strength or modulus of rupture and then compressive strength, and these results were compared with those obtained in the above section (2) by the common curing in water of room temperature and atmospheric pressure. These comparisons are useful to discuss various mixed Portland cements being better than special Portland cements of high iron oxide or silica content.(5) Neat cement paste was tested by the LeChatelier's calliper method curing in autoclave as above mentioned and the increase of opening of calliper was compared to discuss various samples of mixed Portland cement being better than simple Portland cements containing large amount of iron oxide or silica.

Through the brief introduction of the working principle of the brake motor, combined with the theoretical analysis of the brake motor dynamic brake torque test method (directtest method and indirect test method), it is concluded that the selection of the test method is closely related. According to the sensor type, installation position, test range and accuracy requirements. The differences between direct measurement method and indirect measurement method are compared, their respective measurement methods are introduced, and their advantages and disadvantages are summarized. According to the test requirements, the appropriate test method can be selected, and the direct test method and indirect test method can be selected at the same time, to ensure the safety and stability of product

Growing application of composite materials in airframe structures tends to make significant use of bonded constructions. Despite the large work that has been done on adhesive characterization over previous years, various certification-related issues arise in these applications. The available test methods for determining the in situ properties of an adhesive joint for use in the design must be clarified for thick bondlines, where there is a lack of readily available data. Results from three test methods indicated a decrease in the apparent shear strength as the bondline thickness was increased. The apparent shear strength given by the test methods investigated was found to be highly dependent on the adherend bending stiffness, which directly effects the peel stress distributions in the adhesive layer. In the adhesive strength comparisons as a function of test method, it was found that the thin-adherend tests gave different comparative results than the thick-adherend tests, which were primarily a function of the high peel stresses in the thin-adherend joints. This combined state of stress does not give a true view of the apparent shear stress of the adhesive, but rather an indication of the adhesive behavior under this type of combined loading. It is recommended that thick adherends be used when comparing different adhesive systems for apparent shear strength, and that thin adherends should be used for qualitative tests only.

BackgroundThe design of compliant mechanisms requires detailed knowledge about the stiffness properties of their flexible segments. However, there are no standardized test methods for flexure hinges, and therefore the influence of manufacturing-specific effects, such as anisotropy, on the stiffness properties cannot be quantified.ObjectiveThis paper presents novel test methods for variable cross-section flexure hinges subjected to large deformations and pure bending loading, which determine the bending stiffness of flexure hinges over their entire deflection range using a universal testing machine.MethodsThe novel test methods for flexure hinges are based on the tensile test, the four-point bending test (FPBT), and the column bending test (CBT). These test methods were initially formulated for constant cross-section specimens, but are adapted in this study to examine variable cross-section specimens. The derived test methods are validated by using isotropic materials with well-known properties and by comparing the calculated deflections with deflections measured by means of image processing.ResultsThe deflection validation shows that the adapted CBT (aCBT) is accurate over the entire deflection range, achieving curvature of up to kappa =0.40;text {mm}^{-1}, whereas the maximum curvature in the adapted FPBT (aFPBT) is limited by the test methodology to about kappa =0.15;text {mm}^{-1}. At small strains, the flexural modulus determined in the aCBT and aFPBT agrees well with the Young’s modulus determined in the tensile test, as would be expected for isotropic materials.ConclusionThe aCBT proves to be a suitable test method for flexure hinges at large deflections, whereas the stiffness characterization at small deflections can be performed with both the aCBT and the aFPBT. The presented test methods validated on isotropic materials form the basis for characterizing anisotropic flexure hinges with geometry-dependent stiffness properties.

A theoretical model is developed to describe the sound radiation by the surface vibration of in-service truck tires. The tire is modeled as an infinitely long incomplete circular cylindrical shell. The effects of inflation pressure and structural damping are included. The normal displacement, velocity, and acceleration resulting from a fluctuating load are determined using Flügge’s thin shell theory. Through numerical integration of the surface acoustic intensity, the radiated sound power is calculated as a function of damping, inflation pressure, and bending stiffness. Results indicate that the forced acoustic response is insensitive to small changes in the material loss factor and the bending stiffness. The inflation-induced membrane stresses determine the acoustic response character to a large extent and total neglect of the bending stiffness does not seriously affect the calculated sound power. The basic sound radiation mechanism is shown to be the damped progressive wave field on the structure in the vicinity of the applied force. The results indicate that the potential sound reduction might best be approached through study of the tire loading and vibration response mechanisms.

&lt;div class="section abstract"&gt; &lt;div class="htmlview paragraph"&gt;This SAE Standard describes a laboratory test procedure for measuring the vibration damping performance of a system consisting of a damping material bonded to a vibrating cantilevered steel bar. The bar is often called the Oberst bar (named after Dr. H. Oberst) and the test method is often called the Oberst bar test method. Materials for damping treatments may include homogeneous materials, nonhomogeneous materials, or a combination of homogeneous, nonhomogeneous, and/or inelastic (such as aluminum foil) materials. These materials are commonly installed in transportation systems such as ground vehicles, marine products, and aircraft to reduce vibration at resonance, and thus reduce the noise radiation from the vibrating surface. The test method described herein was developed to rank order materials for application on panels using general automotive steel but also may be applicable to other situations or conditions.&lt;/div&gt; &lt;div class="htmlview paragraph"&gt;Damping performance for most materials and systems varies as a function of both frequency and temperature. Accordingly, this test procedure includes provisions for measuring damping over a range of frequencies and temperatures found applicable to many transportation systems. The measured damping performance will be expressed in terms of composite loss factor, η&lt;sub&gt;c&lt;/sub&gt;, within the frequency range of approximately 100 to 1000 Hz, and over the useful temperature range for the given application. The term composite refers to the steel and damping material combination. The composite loss factor is, therefore, dependent upon the thickness, damping, and modulus of both the steel and damping material layer.&lt;/div&gt; &lt;div class="htmlview paragraph"&gt;The test procedure described here is based on the method described in ASTM E756. However, this SAE document differs from the ASTM E756 method in that the SAE practice specifies the bar material, three bar sizes, the mounting conditions of the test samples, and suggested standard interpolation frequencies. This document provides a means of rank ordering damping materials according to their composite loss factor values from test samples that represent typical sheet metal applications.&lt;/div&gt; &lt;div class="htmlview paragraph"&gt;The material properties of the damping material alone, including Young’s modulus E, and the material loss factor η, may be computed from the test samples specified in this document if additional conditions are met. ASTM E756 defines these additional conditions as well as the equations to be used to compute the damping material properties for the single layer (Oberst beam) configuration.&lt;/div&gt;&lt;/div&gt;

&lt;div class="section abstract"&gt; &lt;div class="htmlview paragraph"&gt;This SAE Recommended Practice describes a laboratory test procedure for measuring the vibration damping performance of a system consisting of a damping material bonded to a vibrating cantilevered steel bar. The bar is often called the Oberst bar (named after Dr. H. Oberst) and the test method is often called the Oberst Bar Test Method. Materials for damping treatments may include homogeneous materials, nonhomogeneous materials, or a combination of homogeneous, nonhomogeneous, and/or inelastic (such as aluminum foil) materials. These materials are commonly installed in transportation systems such as ground vehicles, marine products, and aircraft to reduce vibration at resonance, and thus reduce the noise radiation from the vibrating surface. However, the test method described herein was developed to rank order materials used in PASSENGER VEHICLE APPLICATIONS with steel sheet metal and may not be fully applicable to other situations.&lt;/div&gt; &lt;div class="htmlview paragraph"&gt;Damping performance for most materials and systems varies as a function of both frequency and temperature. Accordingly, this test procedure includes provisions for measuring damping over a range of frequencies and temperatures found applicable to many transportation systems. The measured damping performance will be expressed in terms of composite loss factor, η&lt;sub&gt;c&lt;/sub&gt;, within the frequency range of approximately 100 to 1000 Hz, and over the useful temperature range for the given application. The term composite refers to the steel and damping material combination.&lt;/div&gt; &lt;div class="htmlview paragraph"&gt;The test procedure described here is based on the method described in ASTM E 756. However, this SAE document differs from the ASTM E 756 method in that the SAE practice specifies the bar material, the bar size, and the mounting conditions of the test samples. This document provides a means of rank ordering damping materials according to their composite loss factor values from test samples that represent typical passenger vehicle applications.&lt;/div&gt; &lt;div class="htmlview paragraph"&gt;The ASTM E 756 should be followed to determine the damping properties of materials alone, including loss factor η, Young's modulus E, and shear modulus G.&lt;/div&gt;&lt;/div&gt;

A frequency method was proposed to analyze cable tension from measured natural frequencies according to cable tension monitoring of acable stayed bridge during construction. Xinzao Pearl River Grand Bridge was chosen as an example. A geometrical calculation simulation model was established to compare measured cable tension to theoretical cable tension during construction. This paper introduces several cable tension test methods. The principle and theoretical derivations under certain conditions, the method of which fundamental vibration frequency is deduced by dominating vibration frequency, the influence of boundary conditions, bending stiffness, and cable sag on the frequency method testing, and the practical application of frequency method were discussed. A spatial finite element model was established based on finite element software MIDAS. The application of the forward-analysis iterative method was considered to analyze the cable tension during construction. Then the cable tension test method and analysis principle were explored. Finally, it was shown that measured cable tension based on the frequency method was accurate. The measured value is approximately equal to the theoretical value. The experimental error was within the permitted range. The accuracy and reliability of the frequency method was effectively confirmed. The cable tension test for the similar bridges during construction was compatibly applied.

Bending tests of a commercially available sandwich plate with CFRP-fabric skin and acrylic foam core were conducted primarily by means of a three-point bending. The effects of the span and the radius of the tip of the loading device on the bending modulus and strength were examined systematically. Test data on bending rigidity did not coincide with those calculated from a modified beam theory where the effect of the shearing rigidity of the core was incorporated, although the tendency that the bending modulus increased, the span was the same for both experiment and theory. Based on these results, this paper proposes a desirable data reduction scheme by which the correlation between theory and experiment could be made clear. The applicability of a so-called compression bending test was also demonstrated. This paper is the summary of the original work [Itohiya, G. (1999). Mechanical Property Test Method for CFRP/Hard Foam Core Sandwich Plates, MS Thesis, Science University of Tokyo, in Japanese].

The distribution of solar radiation over the earth's surface : Black, J. N. Arch. Meteor. Geophys. Bioklimatol. B, 7(2): 165–189, 1956