This competitive commercial space forces designers and manufactures to produce and supply products with high quality and low prices at a desirable level of reliability. On the other hand, during the design and production process, engineers are always faced with uncertainty. In recent years, to encounter these uncertainties and guarantee the quality and reliability of a system subsequently, reliability-based robust design optimization (RBRDO) algorithms have been developed based on robust design optimization (RDO) and reliability-based optimization (RBDO). In practical engineering, uncertainties of some design parameters or variables are epistemic and only a few samples are available for designer. Generally, some of the RBRDO methods ignore the information in the design process. This approach can lead to an enormous error. Other RBRDO methods ignore this valuable information in the design process. This study, a comprehensive RBRDO framework is developed by combining Bayesian reliability analysis and dimensionality reduction method (DRM) using NSGA2-II multi-objective optimization algorithm. For verification of the proposed algorithm, an engineering example is selected and the effects of epistemic uncertainty on objectives are studied. Moreover, the results of the proposed approach are compared with other existing approaches at a specific case of available data about epistemic uncertainty.

With the advancement of the manufacturing processes and the continuing need for increasingly precise assemblies, consideration of dimensional and geometric tolerances has been of great importance in tolerance analysis of mechanical assemblies. Therefore, in recent decades, several methods have been developed and implemented for calculating the influences of geometric errors of components on the final performance of the assembly. One of the proposed methods for tolerance analysis is the Direct Linearization Method (DLM). However, DLM has significant advantages in dimensional tolerance analysis, due to simplifications used in this technique, it does not have the ability to solve assemblies including free form profiles. In this research, a new method has been proposed to consider the complex profiles in the process of DLM. In the proposed combination method, rational Bezier curves have been used to define component profiles such as elliptical profiles, cams, edge joints, and non-circular profiles that have a complex error variation. Then, by using principles of DLM and rational Bezier equations, the developed algorithm is successfully accomplished. In this way, we can not only use significant advantages of DLM in dimensional tolerance analysis but also it is possible to solve assemblies including a component with complex profiles without any simplification. The developed hybrid approach has been presented in detail by solving an example of assembly tolerance analysis. Finally, validation has been performed and the accuracy of the proposed approach was confirmed using Monte Carlo simulation.
 

Incremental forming method with lower cost and more flexibility can be a suitable alternative for traditional methods of the hole-flanging. In this study, the possibility of square hole-flanging of AL1050 aluminum sheet using incremental forming method has been investigated and the quality of the pyramid flange has been compared with conical flange. The final shape of the flange is defined so that wall angle increases with raising height. The process simulation was performed using Abaqus software and an experimental test was done to validate the simulation results. After performing the experimental tests, flange features such as the final size of the hole, flange height, and wall thickness were measured. The results showed that at the created flange around the circular hole, there is less spring back and more dimensional accuracy, however, it can be flanged a square hole by incremental approach with consideration of the height and hole size. The dimensional measurements showed that the final size of the hole will increase after the hole-flanging. By investigation of the various holes, it was found that in the larger initial hole, increasing the hole size after the flanging will be lower.

Prediction of the dynamic behavior of machining operations during the process is the main challenge of machining simulations. Therefore, the investigation of effective parameters in dynamic behavior is of great importance. Machining vibration is one of the most important factors. This article studied the vibration of the process by developing the dynamic model of the boring bar. The high length-to-diameter ratio of the boring tool and its flexibility cause machining vibrations. The amplitude of the tooltip vibrations is a function of the dynamic characteristic of the tool which can lead to the stability or instability of the process. Tool rigidity at low diameter to length ratios is high, and in most cutting conditions the process is stable. The impact test is used to extract the tool's dynamic parameters and dynamic modeling of the process is developed inside the environment of ACIS software which is a powerful Boundary Representation (B-rep) solid modeling engine and it is proposed a novel method for simulating the dynamic equation of boring bar by using a solid modeling technique in a precise geometric environment. The mechanistic approach is used to modeling cutting mechanistic to develop the dynamic force model in the time domain. Also, dynamic time-domain parameters such as force, acceleration, and displacement in the Simulink environment are simulated. The results confirm that the presented geometrical model by considering the tool dynamics is well capable of estimating the force signal and the chip area changes.

Although there have been several research work  published in the field of simulating and predicting the surface roughness of machining processes, most of them are limited to turning and milling operations.  A few number of studies concerning the internal turning processes is very limited. Furthermore, the existing publications in this field have implemented statistical approaches which not only clearly lack in generality, but also require a huge amount of experiments. In the current research, the simulation of surface roughness has been investigated by using kinematics and dynamics of the process. Despite the numerous applications of this approach in turning operations, this approach has not applied in the internal turning processes. In order to implement the proposed approach, firstly the insert nose profile of the tool has been measured. Then, the surface profile consisting the periodical component of feed marks has been constructed. In the next step, excessive amount of vibrations imposed by the long boring bar have been measured by an accelerometer, which are then converted to displacements and added to the periodical component of the roughness profile. Results obtained from internal turning experiments show that the developed simulation approach has a maximum error of 19.3% in estimating roughness parameters which can be considered as a reasonably accurate results due to the complicated nature of surface roughness.