Paper 7: Mechanical Stresses in Pistons, Gudgeon Pins, and Connecting Rods

1966 ◽  
Vol 181 (8) ◽  
pp. 20-30
Author(s):  
B. Lawton ◽  
D. E. G. Crutcher
Keyword(s):  
Stress Analysis ◽  
Strain Gauge ◽  
Three Dimensional ◽  
Mechanical Stresses ◽  
Connecting Rod ◽  
Mechanical Loads ◽  
Theoretical Methods ◽  
Resistance Strain Gauge ◽  
Induced Stresses ◽  
Theoretical Developments

The paper deals with some experimental and theoretical developments in piston, gudgeon pin, and connecting-rod stress analysis. Stresses induced by mechanical loads have been measured experimentally in rigs using resistance strain gauge techniques; and with two- and three-dimensional photoelastic models. Theoretical methods have been devised to predict mechanically induced stresses on a basis which permits direct comparison with rig results.

scholarly journals Origin and Application of the Twinned Calcite Strain Gauge

Geosciences ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 296
Author(s):  
Richard H. Groshong
Keyword(s):  
Stress Analysis ◽  
Strain Gauge ◽  
Strain Tensor ◽  
Three Dimensional ◽  
Constant Strain Rate ◽  
Axis Orientation ◽  
Order Of Magnitude ◽  
Rate Experiment ◽  
Strain Axis ◽  
Expected Values

This paper is a personal account of the origin and development of the twinned-calcite strain gauge, its experimental verification, and its relationship to stress analysis. The method allows the calculation of the three-dimensional deviatoric strain tensor based on five or more twin sets. A minimum of about 25 twin sets should provide a reasonably accurate result for the magnitude and orientation of the strain tensor. The opposite-signed strain axis orientation is the most accurately located. Where one strain axis is appreciably different from the other two, that axis is generally within about 10° of the correct value. Experiments confirm a magnitude accuracy of 1% strain over the range of 1–12% axial shortening and that samples with more than 40% negative expected values imply multiple or rotational deformations. If two deformations are at a high angle to one another, the strain calculated from the positive and negative expected values separately provides a good estimate of both deformations. Most stress analysis techniques do not provide useful magnitudes, although most provide a good estimate of the principal strain axis directions. Stress analysis based on the number of twin sets per grain provides a better than order-of-magnitude approximation to the differential stress magnitude in a constant strain rate experiment.

Modern Applications of Photo-Elasticity

1948 ◽  
Vol 158 (1) ◽  
pp. 235-250 ◽  
Author(s):  
R. B. Heywood
Keyword(s):  
Stress Analysis ◽  
Three Dimensional ◽  
Polarized Light ◽  
Gear Wheel ◽  
Connecting Rod ◽  
Complicated Shape ◽  
Poppet Valve ◽  
Aero Engine

It has long been known that polarized light may be employed to analyse the stresses occurring in engineering parts. Recent modifications have simplified the apparatus required, so giving a wider scope to the application of photo-elasticity to engineering. The method of preparing transparent models for stress analysis is discussed, and the significance of the photo-elastic fringes is explained. Only the boundary stresses in the model are considered, and their importance is demonstrated by means of examples, such as the modification of the design of aero-engine parts so that a substantial increase in strength is attained. The procedure for evolving the best shape of fillet for a particular set of conditions is given. The three-dimensional “freezing” technique is described, a technique which enables the boundary stresses in parts of complicated shape to be determined, and has the further advantage that an assessment of the elastic distortions may be made. Examples of the application of photo-elasticity include a connecting rod, crankshaft, poppet valve, and gear wheel.

Strength Calculation Analysis of Diesel Engine Linkage Based on Three-Dimensional Contact Finite Element Method

2011 ◽  
Vol 148-149 ◽  
pp. 1202-1208 ◽  
Author(s):  
Gui Xin Wang ◽  
Xiao Bo Li ◽  
Li Jun Guo ◽  
Jun Yan Ma
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Diesel Engine ◽  
Stress Analysis ◽  
Maximum Stress ◽  
Three Dimensional ◽  
Connecting Rod ◽  
Transient Stress ◽  
Calculation Analysis ◽  
Element Method

Adopting a three-dimensional contact finite element method, with complex connecting rod group assembled body model of computation, the fatigue strength of the connecting rod of a certain type of diesel engine was verified. A transient stress analysis was conducted on the connecting rod. Compared with the connecting rod static stretching and compression test, the three-dimensional contact finite element method, which was used to analyze the strength of the connecting rod subassembly, was feasible. Based on the three-dimensional contact finite element method, the connecting rod transient stress analysis results showed that the maximum stress of the connecting rod did not occur under the highest pressure of the cylinder, and the dynamic stress value was less than the static stress value.

Optimization of the Wrist Pin End of an Automobile Engine Connecting Rod With an Interference Fit

1990 ◽  
Vol 112 (3) ◽  
pp. 406-412 ◽  
Author(s):  
Vijay Sarihan ◽  
Ji Oh Song
Keyword(s):  
Finite Element ◽  
Optimum Design ◽  
Three Dimensional ◽  
Stress Singularity ◽  
Design Strategy ◽  
Structural Components ◽  
Connecting Rod ◽  
Fem Model ◽  
Automobile Engine ◽  
Interference Fit

Current design procedures for complicated three-dimensional structural components with component interactions may not necessarily result in optimum designs. The wrist pin end design of the connecting rod with an interference fit is governed by the stress singularity in the region where the wrist pin breaks contact with the connecting rod. Similar problems occur in a wide variety of structural components which involve interference fits. For a better understanding of the problems associated with obtaining optimum designs for this important class of structural interaction only the design problems associated with the wrist pin end of the rod are addressed in this study. This paper demonstrates a procedure for designing a functional and minimum weight wrist pin end of an automobile engine connecting rod with an interference fit wrist pin. Current procedures for Finite Element Method (FEM) model generation in complicated three-dimensional components are very time consuming especially in the presence of stress singularities. Furthermore the iterative nature of the design process makes the process of developing an optimum design very expensive. This design procedure uses a generic modeler to generate the FEM model based on the values of the design variables. It uses the NASTRAN finite element program for structural analysis. A stress concentration factor approach is used to obtain realistic stresses in the region of the stress singularity. For optimization, the approximate optimization strategy in the COPES/CONMIN program is used to generate an approximate design surface, determine the design sensitivities for constrained function minimization and obtain the optimum design. This proposed design strategy is fully automated and requires only an initial design to generate the optimum design. It does not require analysis code modifications to compute the design sensitivities and requires very few costly NASTRAN analyses. The connecting rod design problem was solved as an eight design variable problem with five constraints. A weight reduction of nearly 27 percent was achieved over an existing design and required only thirteen NASTRAN analyses. It is felt that this design strategy can be effectively used in an engineering environment to generate optimum designs of complicated three-dimensional components.

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