A mathematical model of a worm mechanism generated by a conical cutter

Author(s):  
S-C Yang

In this article, an imaginary conical cutter was used to determine the geometric models of the worm—gear mechanism including a worm and a gear. Mathematical models of the worm and the gear were derived using an imaginary conical cutter and gear theory. Based on the geometric relations between the worm and conical cutter surfaces and between the gear and conical cutter surfaces, the worm and the gear were regarded as an envelope to the family of conical cutter surfaces when they rotated for one cycle. Using the developed mathematical model, the stress analysis of the proposed mechanism was examined. The results show that the von Mises stress and volume of the proposed worm and gear were smaller than those of the conventional worm—gear mechanism. Lastly, a numerical example was used to illustrate the geometric model of a gear and a worm with a gear ratio of 30:1.

Author(s):  
S-C Yang

The surface of a gear with ring-involute teeth generated by a rack cutter with ring-involute teeth is a new type of gear. This paper describes a method developed from gear theory for deriving a pinion and a gear with ring-involute teeth. A gear with ring-involute teeth is regarded as an envelope to the family of rack cutter surfaces when the pinion and gear rotate for a cycle. Using a developed mathematical model, the investigation on the undercutting analysis of the proposed gear is studied. Here the kinematic errors are investigated according to the obtained geometric modelling of the designed gear meshing when assembly errors were present. Stress analysis for the proposed gear was performed. Finally, a numerical example is presented to demonstrate the geometric model of a gear with ring-involute teeth and a gear ratio of 3:2.


Author(s):  
S-C Yang

This paper presents a method for determining the mathematical model of an elbow mechanism with a convex tooth and a concave tooth. Based on this method, the mathematical model presents the meshing principles of a conical cutter meshed with a tooth that is either convex or concave. Using the developed mathematical models and the tooth contact analysis, kinematic errors are investigated according to the obtained geometric modelling of the designed gear meshing when assembly errors are present. The influence of misalignment on kinematic errors has been investigated. The goal of the current study is to investigate von-Mises stress for three teeth contact pairs. A structural load is assumed to act on a gear of the proposed mechanism. The von-Mises of the proposed gear is determined. The conical cutter used in the design and manufacture of the convex and concave gear is shown. For example, the proposed mechanism with a transmission ratio of 3:2 was determined with the aid of the proposed mathematical model. Using rapid prototyping and manufacturing technology, an elbow mechanism with a convex gear, a concave gear and a frame was designed. The RP primitives provide an actual full-size physical model that can be analysed and used for further development. Results from these mathematical models are applicable to the design of an elbow mechanism.


2013 ◽  
Vol 739 ◽  
pp. 431-436
Author(s):  
Ho Kyung Kim

In order to evaluate the fatigue endurance for an ultra lightweight inline skate frame, FEM analyses was performed. The tensile properties and an S-N curve were determined through tensile and fatigue tests on a modified Al-7075+Sc alloy. The yield and ultimate tensile strengths were 553.3 MPa and 705.5 MPa, respectively. The fatigue endurance limit of this alloy was 201.2 MPa. To evaluate the fatigue endurance of the inline skate frame, the S-N data were compared with the stress analysis results through FEM analyses of the frame. The maximum von Mises stress of the frame was determined to be 106 MPa through FEM analysis of the frame, assuming that the skater weight is 75 kg. Conclusively, on the basis of the fatigue limit, the inline skate frame has a safety factor of approximately 2.0.


2010 ◽  
Vol 452-453 ◽  
pp. 541-544 ◽  
Author(s):  
Yu Pu Song ◽  
Han Yong Liu

This work presents a study of a fatigue test and a finite element analysis on an arch bridge stainless steel suspender with threaded connections. A suspender which had a diameter of 70mm was tested under axial tensile loads range from 430kN to 700kN. The suspender was sudden failure from the thread root of the first loaded tooth in the pin after 1546609 cycles. Then, a two-dimensional axisymmetric modeling ignoring the helix angle of the thread was established with finite element software ANSYS to perform a stress analysis of the threaded connection. The stress concentration factors (SCFs) at the root of the teeth of pin were investigated under the applied external loading. The conclusive results had been drawn from the analysis including the location and the value of maximum SCF in the pin. Finally, the location and the value of the maximum von Mises stress were given. The results showed that the location of the fracture surface was consistent with the location of the maximum von Mises stress.


2019 ◽  
Vol 16 (03) ◽  
pp. 1842006 ◽  
Author(s):  
Xinyang Cui ◽  
Qingshuai Ren ◽  
Gaoyang Li ◽  
Zihao Li ◽  
Aike Qiao

The stents’ adaptability and safety in realistic and idealized stenotic coronary model were compared to investigate the influence of artery geometry parameter on stent fatigue life. The stents’ fatigue resistance ability was calculated using Goodman diagram, and the cycle to failure, the fatigue life, and the fatigue safety factor (FSF) were analyzed. Although the peak top of the von Mises stress was located at the bending area of crowns, the stress distributions were different in the two models. Considering the safety and accuracy, it is necessary to use a realistic geometric model to calculate the stent fatigue performance.


2018 ◽  
Vol 6 (7) ◽  
pp. 272-277
Author(s):  
Maj Pankaj Awasthi ◽  
Lt Col Sonali Sharma ◽  
Maj Summerdeep Kaur

Aim: To study the stress distribution in Class 2 Inlay of various materials on Mandibular Molar. Background: Inlays are fabricated using different materials like gold, porcelain or a cast metal alloy. Difference in the modulus of elasticity of the material and tooth structure would lead to generation of stresses leading to failure of the restoration or loss of tooth structure. Finite Element Analysis (FEA) is a mathematical tool for stress analysis in a structure. Von Mises stress being the combination of normal and shear stresses which occur in all directions. This stress has to be given diligent importance while considering the type and material of restoration to achieve long-term success. Methodology: In our study, stress analysis was performed on the mandibular first molar using a stress analysis software (ANSYS). A computer model of mandibular first molar was generated along with generation of an inlay volume using a FEA software preprocessor. The models with the class 2 inlays of different materials were subjected to 350N and 800N load simulating normal masticatory force and bruxism respectively. Maximum and minimum stresses were calculated for each model separately. Results: Von Mises stress distribution for different materials for normal masticatory forces and bruxism were studied and evaluated. Conclusion: The study revealed the maximum and minimum stresses imposed over the tooth and the restoration and provides insight into the areas which are more prone to fracture under the occlusal load.


2021 ◽  
Vol 31 (6) ◽  
pp. 341-347
Author(s):  
Emad Toma Karash ◽  
Tymor Abed Alsttar Sediqer ◽  
Mohammad Takey Elias Kassim

In this research, three mathematical models were designed, the first consisting of concrete, the second from carbon fiber, and the third from s-glass fiber, in order to compare the strength of composite materials to different stresses and deformations, because composite materials are better than concrete in terms of weight and shape and do not need to be applied to painting operations in addition to the fact that their thermal insulation is higher than Concrete in high proportions. From the results of the comparison, it was found that the second model was the best model in terms of bearing deformations, as the deformation percentage in it did not exceed the deformation of concrete a lot, reaching (17%), which is a very small percentage, and the stresses towards pregnancy for the second and third models were much better than the bearing of the first model, but the results indicate that the Von Mises Stress in the second model is higher than the first model by a percentage (57%), while the comparison of the third model with the first was the rate of increase percentage (47%).


2011 ◽  
Vol 243-249 ◽  
pp. 938-941
Author(s):  
Bin He ◽  
Jun Long Lu

To research the safety of an underground defense project and the impact to other buildings, applying basic mechanics principles, established two types of mathematical model for arch about the project, and analyzed stress in different directions of ground arch structure. The data shows that the results were very different in different mathematical models, and mathematical models should be considered as close to actual stress situation in structural analysis. In the structural analysis involved soil, spatial finite element model is more accurate and reasonable than truss finite element model.


2018 ◽  
Vol 917 ◽  
pp. 316-320
Author(s):  
Mehmet Yetmez

In this study, modal stress analysis of carbon fiber plain weave cracked composite beams under compression is considered. General-purpose finite element code MSC. Marc is used for the finite element beam models. Before understanding the compression effect on the beam, dynamic characteristics of the models are compared with the experimental evaluations. Investigation of quasi-static and dynamic (equivalent von Mises stress and elastic strain energy density) behavior of the plain weave cracked beams with two different thicknesses under compression is examined numerically. Results are given in tabular and graphical form.


2012 ◽  
Vol 81 (2) ◽  
pp. 211-215
Author(s):  
Lucie Urbanová ◽  
Iva Blažek-Fialová ◽  
Robert Srnec ◽  
Jan Pěnčík ◽  
Přemysl Kršek ◽  
...  

The study deals with the possibility of substituting time- and material-demanding mechanical testing of a bone defect fixation by mathematical modelling. Based on the mechanical model, a mathematical model of bone-implant construct stabilizing experimental segmental femoral bone defect (segmental ostectomy) in a miniature pig ex vivo model using 4.5 mm titanium LCP was created. It was subsequently computer-loaded by forces acting parallel to the long axis of the construct. By the effect of the acting forces the displacement vector sum of individual construct points occurred. The greatest displacement was noted in the end segments of the bone in close proximity to ostectomy and in the area of the empty central plate hole (without screw) at the level of the segmental bone defect. By studying the equivalent von Mises stress σEQV on LCP as part of the tested construct we found that the greatest changes of stress occur in the place of the empty central plate hole. The distribution of this strain was relatively symmetrical along both sides of the hole. The exceeding of the yield stress value and irreversible plastic deformations in this segment of LCP occurred at the acting of the force of 360 N. These findings are in line with the character of damage of the same construct loaded during its mechanic testing. We succeeded in creating a mathematical model of the bone-implant construct which may be further used for computer modelling of real loading of similar constructs chosen for fixation of bone defects in both experimental and clinical practice.


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