Cost Sensitivity Analysis for Laser Powder Bed Fusion

Laser Powder Bed Fusion is the most widespread additive manufacturing process for metals. In literature, there are several analytical models for estimating the manufacturing cost. However, few papers present sensitivity analyses for evaluating the most relevant product and process parameters on the production cost. This paper presents a cost model elaborated from previous studies used in a sensitivity analysis. The most relevant process parameters observed in the sensitivity analysis are the 3D printer load factor, layer thickness, raw material price and laser speed

Asymptotically AdS brane black holes

We study the possibility of having a static, asymptotically AdS black hole localized on a braneworld with matter fields, within the framework of the Randall and Sundrum scenario. We attempt to look for such a brane black hole configuration by slicing a given bulk spacetime and taking Z_2 symmetry about the slices. We find that such configurations are possible, and as an explicit example, we provide a family of asymptotically AdS brane black hole solutions for which both the bulk and brane metrics are regular on and outside the black hole horizon and brane matter fields are realistic in the sense that the dominant energy condition is satisfied. We also find that our braneworld models exhibit signature change inside the black hole horizon.Comment: 21 pages, 6 figures, RevTex; v2: clarifications added, figures updated, eq.31 corrected, comment on small four dimensional cosmological constant limit added, character size increased, results unchanged. v3: reference added, version accepted in Phys. Rev. D (2006

A Framework to Collect and Reuse Engineering Knowledge in the Context of Design for Additive Manufacturing

Design for AM (DfAM) requires the definition of Design Actions (DAs) to optimize AM manufacturing processes. However, AM understanding is still very blurred. Often designers are challenged by selecting the right design parameters. A method to list and collect DfAM DAs is currently missing. The paper aims at providing a framework to collect DfAM DAs according to a developed ontology to create databases (DBs). DBs were tested with two real case studies and geometric features to improve identified. Future developments aim at widening the database to provide all-around support for AM processes

Direct fabrication through electron beam melting technology of custom cranial implants designed in a phantom based haptic

Repairing critical human skull injuries requires the production and use of customized cranial implants and involves the integration of computer aided design and manufacturing (CAD and CAM). The main causes for large cranial defects are trauma, cranial tumors, infected craniotomy bone flaps and external neurosurgical decompression. The success of reconstructive cranial surgery depends upon: the preoperative evaluation of the defect, the design and manufacturing of the implant, and the skill of the operating surgeon. Cranial implant design is usually carried out manually using CAD although this process is very time-consuming and the quality of the end product depends wholly upon the skill of the operator. This paper presents an alternative automated method for the design of custom-made cranial plates in a PHANToM \uae-based haptic environment, and their direct fabrication in biocompatible metal using electron beam melting (EBM) technology

LTV stochastic systems stabilization with large and variable input delay

In this paper we propose a solution to the state-feedback and output-feedback stabilization problem for linear time-varying stochastic systems affected by arbitrarily large and variable input delay. It is proved that under the proposed controller the underlying stochastic process is exponentially centered and mean square bounded. The solution is given through a set of delay differential equations with cardinality proportional to the delay bound. The predictor is based on the semigroup generated by the closed-loop system in absence of delay, and its computation is described by a numerically reliable and robust method. In the deterministic case this method generates the same optimal trajectories as in the delay-less case

An analytical cost estimation approach for generic sheet metal 3D models

This paper defines a systematic workflow for production cost estimation of sheet metal stamped components. The approach represents a solution toward the adoption of Design to Cost methods during early product design. It consists in a sequence of steps that, starting from a 3D CAD model with annotations (material, roughness and tolerances) and production information (batch and production volume) leads to the manufacturing cost through an analytic cost breakdown (raw material, stamping and accessory processes, setup and tooling). The calculation process mainly consists in a first step where geometric algorithms calculate the sheet metal blank (dimensions, shape, thickness) and specific product features (e.g. flanges, louvers, embossing, etc.). The following steps allow to calculate the raw material, the stamping process and the process-related parameters, which are the manufacturing cost drivers (e.g. press, stamping rate/sequence/force and die dimensions/weight). The manufacturing cost is the sum of the previous calculated items. Testing the approach for three different components, the average absolute deviation measured between the estimated and actual cost was less than 10% and such a result looks promising for adopting this method for evaluating alternative design solutions