Experimental LCF Study of a Probabilistically Optimized Double Notch Specimen Geometry for Validation of Deterministic and Probabilistic Design Concepts

2021 ◽  
Author(s):  
Marcel Adam ◽  
Sebastian Schmitz ◽  
Suhas Suresh ◽  
Dirk Kulawinski ◽  
Alexander Erbe ◽  
...  
Author(s):  
Marcel Adam ◽  
Sebastian Schmitz ◽  
Suhas Suresh ◽  
Dirk Kulawinski ◽  
Alexander Erbe ◽  
...  

Abstract In this work, the design and testing of a new LCF double notch specimen geometry is presented. The deterministic CMB model and a probabilistic model for LCF which considers size effects are simultaneously applied as shape optimization functional. In order to demonstrate the potential of the statistical size effect consideration, the probability of crack initiation is maximized in the milder notch while the deterministic LCF life is minimized in the sharp notch. This also increases the likeliness of an experimental validation success considering the issues of high scatter in material properties and limited test resources (test plan optimization). Specimens of a high-chromium forged steel for elevated application temperatures have been manufactured according to this specimen design and a systematic and advanced experimental testing campaign is conducted to prove the hypothesis. In-situ time-resolved alternating current potential drop measurements in combination with load-triggered digital image acquisition at both notches are applied in order to enable determination and quantification of crack initiation and growth at superior accuracy during LCF cycling. These experimental and further post-experimental analyses confirm that cracking in the mild notch always occurred in the first place which has been expected for most test outcomes according to the probabilistic model predictions. Crack initiation in the sharp notches on the other hand, which has been expected to occur first on the basis of conventional deterministic predictions, could not be detected at all.


Author(s):  
Julian D. Booker

Abstract Deterministic design fails to provide the necessary understanding of the variability associated with the properties of materials, manufacturing tolerances and in-service loading. Probabilistic design offers much potential in this area, providing an effective way of determining product life-time estimates, reducing failure costs and aiding the process of weight optimization in product design, but has yet to be taken up widely by manufacturing industry. In this paper, case studies are used to explore some important probabilistic design concepts and introduce methods that allow reliability performance measures to be assessed for product designs early in the product development process. The methods described are used in conjunction with Failure Mode and Effects Analysis (FMEA) to facilitate the setting of reliability targets for design proposals.


Author(s):  
Arthur V. Jones

With the introduction of field-emission sources and “immersion-type” objective lenses, the resolution obtainable with modern scanning electron microscopes is approaching that obtainable in STEM and TEM-but only with specific types of specimens. Bulk specimens still suffer from the restrictions imposed by internal scattering and the need to be conducting. Advances in coating techniques have largely overcome these problems but for a sizeable body of specimens, the restrictions imposed by coating are unacceptable.For such specimens, low voltage operation, with its low beam penetration and freedom from charging artifacts, is the method of choice.Unfortunately the technical dificulties in producing an electron beam sufficiently small and of sufficient intensity are considerably greater at low beam energies — so much so that a radical reevaluation of convential design concepts is needed.The probe diameter is usually given by


Author(s):  
Andrea CAPRA ◽  
Ana BERGER ◽  
Daniela SZABLUK ◽  
Manuela OLIVEIRA

An accurate understanding of users' needs is essential for the development of innovative products. This article presents an exploratory method of user centered research in the context of the design process of technological products, conceived from the demands of a large information technology company. The method is oriented - but not restricted - to the initial stages of the product development process, and uses low-resolution prototypes and simulations of interactions, allowing users to imagine themselves in a future context through fictitious environments and scenarios in the ambit of ideation. The method is effective in identifying the requirements of the experience related to the product’s usage and allows rapid iteration on existing assumptions and greater exploration of design concepts that emerge throughout the investigation.


2017 ◽  
Vol 13 (9) ◽  
pp. 6475-6479
Author(s):  
M. Arulraj ◽  
P.K. Palani ◽  
L. Venkatesh

Aluminium based composites exhibit many attractive material properties such as increased stiffness, wear resistance, specific strength and vibration damping and decreased co-efficient of thermal expansion compared with the conventional aluminium alloys. Aluminium Matrix Composites consist of non-metallic reinforcement which offers advantageous properties over base material. Reinforcements like SiC, B4C and Al2O3 are normally preferred to improve the mechanical properties. Here Aluminum LM25 is selected as matrix material while Silicon carbide and Boron carbide are selected as reinforcement material. The fabrication of aluminium matrix was done by stir casting method. In the present study an attempt has been made to investigate the effect of three major stir casting parameters (stir speed, stir duration and preheated temperature of reinforcement material) on stir casting of Aluminium LM25 - SiC - B4C composite. Experiments were conducted based on Taguchi methodology. Taguchi quality design concepts of L9 orthogonal array has been used to determine S/N ratio and through S/N ratio a set of optimum stir casting parameters were obtained. The experimental results confirmed the validity of Taguchi method for enhancing tensile strength of castings. 


2020 ◽  
Vol 17 (2) ◽  
pp. 97-120
Author(s):  
Shabana Bibi ◽  
Yuan-Bing Wang ◽  
De-Xiang Tang ◽  
Mohammad Amjad Kamal ◽  
Hong Yu

: Some species of Cordyceps sensu lato are famous Chinese herbs with significant biological activities, often used as edible food and traditional medicine in China. Cordyceps represents the largest entomopathogenic group of fungi, including 40 genera and 1339 species in three families and incertae sedis of Hypocreales. Objective: Most of the Cordyceps-derivatives have been approved clinically for the treatment of various diseases such as diabetes, cancers, inflammation, cardiovascular, renal and neurological disorders and are used worldwide as supplements and herbal drugs, but there is still need for highly efficient Cordyceps-derived drugs for fatal diseases with approval of the U.S. Food and Drug Administration. Methods: Computer-aided drug design concepts could improve the discovery of putative Cordyceps- derived medicine within less time and low budget. The integration of computer-aided drug design methods with experimental validation has contributed to the successful discovery of novel drugs. Results: This review focused on modern taxonomy, active metabolites, and modern drug design techniques that could accelerate conventional drug design and discovery of Cordyceps s. l. Successful application of computer-aided drug design methods in Cordyceps research has been discussed. Conclusion: It has been concluded that computer-aided drug design techniques could influence the multiple target-focused drug design, because each metabolite of Cordyceps has shown significant activities for the various diseases with very few or no side effects.


2005 ◽  
Vol 2005 (11) ◽  
pp. 4417-4430
Author(s):  
Eric J. Wahlberg ◽  
Robert B. Stallings ◽  
A. Ron Appleton
Keyword(s):  

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