Papers by Keyword: Surface Topology

Abstract: The operational characteristics of metal components are often determined by the status of surface. In mechanical loading of solid bodies, the impact of the surface properties on formation and spreading of surface cracks is obvious, mainly as regards cyclic loading. Therefore, it is important to pay attention to knowledge of surface properties and their improvement.Cold plastic deformation is the easiest way to change the mechanical properties of the materials. The possibility of surface strengthening by ball or roller burnishing was found 80 years ago and since then has spread mainly into engineering and the automotive industry.In the authors’ workplace, experiments for surface layer hardening without ultrasound were realized with a newly developed device where the compressive force was applied statically, not dynamically. In the experimental part, we focused on the status of surface layers, especially the microstructure, hardness and roughness.

Abstract: The performance of the micro nozzle is determined primarily by its machined surface topology and geometric profile. A circular cross-section micro-Laval nozzle is modeled and studied by using numerical simulation in this paper. The real residual height and residual area of machined nozzle surface with ball-end milling cutter are proposed. A micro-Laval nozzle was machined successfully. It is found that the ball end milling cutter with large radius is suitable for finishing operations in the viewpoint of nozzle performance. Moreover, the serial process of drilling and milling has been proved by experiments with which both high-level machining accuracy and performance can meet the nozzle requirement.

Abstract: Evidence regarding a fracture event is absolutely and definitively recorded by Nature during the fracture process. That record is in the form of the general macrocrack pattern and the surface topological features of the newly formed fracture surface. In reality, it is the only perfect record of what actually occurred during a fracture. Whenever a conflict or controversy arises regarding a fracture, it is the moral and scientific responsibility of the fractographer to analyze and interpret the record of the fracture as it was created by Nature. It is further necessary for the fractographer to then inform and educate the members of the legal community (lawyer, judge and jury) as to exactly what happened during the failure. This educational process is necessary so that the legal community can collectively understand the history of the fracture and arrive at a just and fair decision regarding responsibility and potential liability for the failure. This paper describes the overall process from the beginning of the fracture examination of the failed artifact to the final appearance in court leading to a decision by the judge or a jury. Both the technical and the human factors are addressed with varying degrees of detail.

Abstract: This work is focused on laser modification of polymers with different angles of incidence. Periodic surface structures generated by linearly polarized F2 laser light (157 nm) on polyethyleneterephthalate (PET) were studied. Atomic force microscopy was used to study the topological changes induced by the laser irradiation. The laser irradiation induces the formation of periodic ripple structures, the width of and the height being angle dependent. The periodic structures were formed with the laser fluence 4.70 mJ/cm2. The laser modified PET foils were coated with a 50 nm thick gold layer by sputtering. After Au deposition on the laser PET foils with ripple structure, the roughness of surface decreases in comparison to PET with ripples without Au coating.

Abstract: Today, the trend in die and mold manufacturing is to pursue high-quality surface topology using high-speed finish milling operation. This paper presents a new approach to optimize machining conditions according to the required material removal rate (MRR), focusing on obtaining a high-quality surface. In this approach, the prediction model of surface roughness using the 2-staged artificial neural network (ANN) is employed for the objective function. Furthermore, an additional surface quality criterion is also used for the optimization problem using the genetic algorithm. It has been investigated that optimized machining conditions can be selected to obtain the high-quality surface within allowable reliability while maintaining a high-quality surface, under the given desired MRR.