Stress Triaxiality and Lode Angle Parameter Characterization of Flat Metal Specimen with Inclined Notch

The stress state has an important effect on the deformation and failure of metals. While the stress states of the axisymmetric notched bars specimens are studied in the literature, the studies on the flat metal specimen with inclined notch are very limited and the stress state is not clearly characterized in them. In this paper, digital image correlation and finite element simulations are used to study the distribution of strain and stress state, that is stress triaxiality and Lode angle parameter. Flat specimen with inclined notch was tested to extract the full field strain evolution and calculate stress state parameters at three locations: specimen centre, notch root and failure starting point. It is found that compared with the centre point and the notch root, the failure initiation point can better characterize the influence of the notch angle on the strain evolution. Conversely, the centre point can more clearly characterize the effect of the notch angle on stress state, since the stress states at the failure point and the notch root change greatly during the plastic deformation. Then the calculated stress state parameters of the flat metal specimen with inclined notch at the centre point are used in Wierzbicki stress state diagram to establish a relationship between failure mode and stress state.

Investigation of the Near-Tip Stress Field of a Notch Terminating at a Bi-Material Interface

The article deals with the problem of a sharp corner, the tip of which is located on the bi-material interface. The paper presents a qualitative and quantitative description of singular stress fields occurring in the tip area of such a stress concentrator. The qualitative description was obtained by solving the problem of the plane theory of elasticity with appropriately defined boundary conditions. To obtain a quantitative description, it was necessary to determine the values of generalised stress intensity factors (GSIFs). The GSIFs were determined using the developed analytical-numerical method. The calculations were made for various load variants (uniaxial/biaxial tension load, shear load) and notch positions (single/double edge-notched plate, centre-notched plate). Additionally, the impact of notch geometry (height and opening angle) and relative stiffness (Young’s moduli ratio of both components of bi-material) on GSIFs was investigated. It has been noticed that with a decrease in the relative stiffness and an increase in the notch angle or its height, the normalised GSIFs values increased. The obtained results were compared with the data available in the literature and their satisfactory agreement with those presented by other scientists was found.

Numerical Study on Buckling Resistance of Uniaxially Compressed Laminates Containing V-Shaped Edge Notch

The purpose of this study is to investigate the impact of a V-shaped cutout on the buckling strength of E-glass epoxy composite laminates. In aircraft components, cutouts are more often used for inspection, ventilation, access to critical areas, fitting a particular component, and increasing the strength to weight ratio of the structure. In this paper, symmetric and antisymmetric laminates of E-Glass/Epoxy unidirectional are used and the effect of notch parameters such as notch radius(r), depth of the notch(h), and notch angle(α) is observed under monoaxial compression. Effects of end conditions and plate aspect ratio(l/b) are analyzed. It is observed that the notch radius does not have a considerable effect on buckling strength but the notch angle after 90⁰ shows a good dip in buckling loads as compared to 30⁰,45⁰, and 60⁰. Depth of notch and end conditions creates a considerable loss in buckling strength. As the h/b ratio is increased, the drop in buckling strength becomes significant. Clamped -pinned end condition of the plate gives a lower value of load multiplier as compared to clamped -clamped. As we increase the l/b ratio of the plate, buckling of the plate becomes easier. The position of the notch (a) also affects buckling strength which is maximum for a/l=0.25 and minimum for a/l=0.5.

Effect of Notch on Strain Rate Concentration Factor of 304 Stainless Steel Bar

In this study, the notch effect of different types of 304 stainless steel rod notch is studied because of the problem of difficulty in measuring the notch root strain of 304 rod stainless steel, and the parameters of the annular notch root are analyzed. The notch angle, notch depth, and notch root radius are the main parameters of the stress field affecting the annular notch, and the mathematical expression of the strain rate concentration factor is derived. In order to verify the accuracy of the theory, the mechanical model of 304 stainless steel bar is established by finite element and numerical simulation calculation. The results show that the theoretical and finite elements have a high degree of agreement. When the notch angle increases, both theoretical and finite elements show a downward trend. When the notch depth of 304 stainless steel bar increases, both theoretical and numerical simulations show an increasing trend. The notch root radius of 304 stainless steel bar increases with decreasing numerical simulation.

Standardization of the Laser Notching Method for Measuring Fracture Toughness in Structural Ceramics

The single-edge V-notched beam (SEVNB) method based on the laser notching approach can effectively overcome the shortcoming of time-consuming and avoid large errors in traditional fracture toughness measurement ways, nevertheless the laser notching method has not yet been standardized. Taking oxide (ZrO2 and Al2O3), carbide (SiC), nitride (Si3N4) and boride (ZrB2-based) ceramics as the research objects, this paper systematically discussed the effects of notch tip sharpness, notch depth and equivalent notch angle on the measured value of fracture toughness, thereby clearly defined the range of these parameters that required for measuring the fracture toughness accurately. Furthermore, in order to give full play to the advantages of the laser notching method, the feasibility of sample miniaturization was also discussed. This study could provide important data reference and theoretical basis for the standardization of laser method in the near future.

Triple Band Slotted Patch Antenna with a Notch for Wi-MAX Communications

A conventional probe fed square patch antenna with a triangular notch & a rectangular slot with perturbation is designed and simulated for triple band operation for applications in communication systems like Wi-MAX systems is presented. The antenna is designed on the glass epoxy FR4 substrate. With the fixed feed point location, the notch angle is varied from 1800 to 1400 resulting in single and dual resonance behavior of patch antenna. With the notch angle from 1800 to 1650 , antenna resonates at a single frequency but on further reduction of notch angle from 1650 to 1400 , dual resonance behavior is noticed with improved bandwidth. The optimum performance is obtained for a notch angle of 1500 . The maximum radiation efficiency of ⁓ 40% is obtained. Further, a rectangular slot with perturbation at shorter edges give rise to additional resonant frequency. The other performance parameters of antenna are analyzed by varying notch angle and its position.

Typical features of morphometric parameters of the mandible in adults

Objective: to develop a classification of mandibular forms and to study typical features of the morphometric characteristics of this bone in adults. Materials and methods. The study was conducted on 150 lower jaws of adults. To determine the shape of the lower jaw, four morphometric parameters were measured: angular width, projection length from the corners, branch height, smallest branch width, and three morphometric indexes were introduced: 1 - the long-length longitudinal index of the lower jaw; 2 - longitude latitudinal index of the body of the lower jaw; 3 - latitudinal-altitude index of the branches of the lower jaw. According to these indices, 9 groups of jaws with different shapes were identified. In these groups, the values of 35 morphometric parameters of the body and branches of the lower jaw were studied. Results. It was found that statistically significant differences (p <0.05) between the groups of jaws, determined by the value of the altitude-longitude index of the lower jaw and the longitude-latitude index of the body of the lower jaw, exist between the same morphometric parameters: angular width, projection length from the corners and chin angle , and most of the morphometric parameters of the body and branches of the lower jaw do not statistically significantly differ between the extreme forms (dolicho- and brachi, lepto- and eurimandibular). There are statistically significant differences between the jaw groups, systematized by the latitude-altitude index of the branch of the lower jaw (p <0.05) for most of the studied indicators of the branch of the lower jaw: branch height, smallest branch width, notch width, notch angle, base of the coronoid process , the base of the condylar process, the distance from the front edge of the lower jaw branch to the opening of the lower jaw, the distance from the notch of the lower jaw to the opening of the lower jaw, the distance from the angle of the lower jaw to the opening of the lower jaw. It has been proved that in the lower jaws with a hypsiramimandibular form, the values of the smallest branch width, the base length of the coronoid and condylar processes, as well as the distance from the front edge of the branch to the opening of the lower jaw are significantly smaller, however, the values of the branch height, notch angle, notch width, notch distance the angle of the lower jaw to its opening is larger compared to the platyramimandibular form (p˂0.05). Conclusion. The greatest number of differences in the value of morphometric parameters is observed during the systematization of the lower jaw according to the shape of its branch. This can be explained by the fact that it is under the direct influence of the masticatory muscles, performing not only supporting, protective, but also motor function.

ANALISA POLA SPESIMEN PLASTIK UJI PUKUL CHARPY DENGAN MENGGUNAKAN PRINTER 3D

Impact testing is needed to measure the toughness of an object that requires a specimen as material to be requested. Where Impact testing specimens from metal that be moulded by casting cannot be made perfect because the angles of the notch are very difficult to make. For this reason, researchers try to make plastic specimens produced from 3D printers where notches or angles in the test specimens can be made precisely using a 3D printer. The design pattern of the plastic test specimen was made according to ASTM standard and tested using the Charpy test having a length of 73.6 mm, a width of 12.7 mm and a thickness of 10 mm, a notch shaped "V" with an angle of 45 ° alongside a notch height of 2, 54 mm . after that it is drawn 3D using 3D software then saved in STL file format then opened, saved and printed in the default software of the 3D printer. The variables researched are layer thickness and temperature. Analysis of the plastic test specimen by using a 3D printer the first is Failed in Impact testing occurred because the placement of the specimen on the charpy compressive test instrument laying would not be straight with the pendulum. The notch angle should be straight with the pendulum by checking the straight position by being photographed from the back and front of the specimen and pendulum. The second obtains if it gets a gap in the slice of the plastic specimen from the type of layer, the energy provided is smaller so that the energy absorbed can be read in the testing process through charpy. The third the plastic specimens code A and code B is getting more layers, the more energy absorbed. The fourth which shows the difference in the nozzle temperature for the plastic test specimens that are set using a nozzle temperature of 200 ° C, the initial energy given is greater and the specimen is stronger receiving the energy load than test plastic specimen using a 180 ° C temperature nozzle.

Comprehensive Analysis of Mechanical Properties of CB/SiO2/PVDF Composites

Damage is a key problem that limits the application of polymer membranes. In this paper, conductive carbon black (CB) and silicon dioxide (SiO2)-reinforced polyvinylidene fluoride (PVDF) composites were prepared using a solution mixing method. Through a uniaxial tensile test, the fracture and damage characteristics of the material were analyzed. When the structure had inevitable notch damage, changing the notch angle was very helpful for the material to bear more load. In addition, when there were two kinds of fillers in the PVDF matrix at the same time, there was an interaction between particles. The microstructure of the composite was characterized by scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), and thermogravimetric (TG) analysis. The experimental results indicate that, when the ratio of CB:SiO2:PVDF was 1:4:95, the general mechanical properties of the composite were the best.