Engineering applications using CAD based application programming interface

Automating the design process of a product or a system can provide engineers and designers with many benefits. As such, repeatable tasks that are time consuming can be handled automatically and with minimal human attention. This is achieved by using the API (Application Programmable Interface) of CAD systems in order to create macros or even develop software applications. The present paper deals with an application that has been developed with the API of a general purposes CAD system. This application automates the design process of a standard pneumatic double acting cylinder based on the appropriate inserted parameters (ISO 15552).The design process begins with the creation of a series of components developed as solids, and extends to the extraction of basic attributes and properties from the complete mechanical assembly. Finally, the assembled models and the extracted data can be used to further study the design of the pneumatic double acting cylinder. It is expected in the future to expand the features of the presented application in order to automate the design process of other related mechanical systems

A dynamical systems investigation of lower extremity coordination during running over obstacles

Objective. To investigate intralimb coordination during running over a level surface and over obstacles of three different heights. Design. The phasing relationships between the foot and leg motions in the frontal plane, and the shank and thigh motions in the sagittal plane were used to compare patterns of coordination. Background. The coordinated actions of lower extremity segments are necessary to absorb the impact forces generated during running. The behavioral patterns of these segments can be studied under changing task demands using analysis techniques from the Dynamical Systems Theory. Methods. Ten subjects ran at their self-selected pace under four conditions: over a level surface and over obstacles of different heights (5%, 10%, 15% of their standing height). A force platform was used to record impact forces during landing after obstacle clearance, while kinematics were collected using a two-camera system. Results. The increases in obstacle height resulted in significant changes in impact forces (34% increase between the two extreme conditions) and more in-phase relationships between the segments during early stance. No changes were observed in the variability of the phasing relationships. Conclusions. The coordination changes observed might be compensatory strategies aimed to reduce forces and potential injury. However, since the impact forces still increased significantly, it is also possible that the observed changes might be at-risk movement patterns predisposing runners to injury. Relevance Tools from the Dynamical Systems Theory, such as intralimb coordination, can be used as a way to evaluate running mechanics so that comparisons can be made to various patient populations in subsequent studies. This approach might be a viable alternative to examine questions in therapeutics

Infield composites repair techniques for combat aircraft: Research and development perspective

Combat aircraft that are damaged and reside on the ground are completely ineffectual to air component commanders. Aircraft battle damage repair (ABDR) aims to rapidly restore these damaged aircraft to some level of combat capability. To be effective, the repairs must allow the aircraft to return to combat in time to affect the outcome of the battle. The Composite Group at Department of Materials, Queen Mary College, University of London, has worked on various aspects of the rapid repair concept for composite materials. In the present paper in particular, the vacuum infusion method is highlighted as an alternative reliable bonded infield repair approach for composite monolithic skins. The study identifies certain technical challenges that the repair technique must address to be viable. Results are presented from a novel toughening method developed by incorporating polyester and carbon veils at the infused bondline, while single scarf coupons as well as full scale testing data demonstrate the effectiveness of the vacuum infusion repair technology in accordance with the ABDR specifications. © 2007 W. S. Maney & Son Ltd

Experimental and finite element analysis on the performance of vacuum-assisted resin infused single scarf repairs

The high quality composite components produced by the modern manufacturing techniques necessitate the evolvement of repair procedures that produce comparable, in terms of structural integrity, post-repaired components. The vacuum-assisted resin infusion processing method is essentially a modern composite fabrication process and it is currently adapted in the production line of many industries. The technique is considered in the current paper as a repair route where a scarf recess is used as a mould cavity. The effectiveness of the repair technique is evaluated by examining two configurations that are constructed under certain scarf patch design guidelines. The fabrication and quality control procedures of the vacuum-assisted resin infused repair patches are described and experimental tests are carried out to measure their performance. Finite element analysis of the repair configurations is performed, in order to analyze and compare the repair geometries selected. The critical stressed areas from the analyses are identified as potential fracture locations and the stress distributions are used to predict the strength of the repairs using the Tsai-Wu and average stress failure criterion (ASFC). The FE (finite element) results are found to be in good agreement with the experimental findings. The repairs present high strengths approaching that of the control specimens with neither of the configurations perpetuating failure cohesively within the bondline for the taper ratios examined, validating in that way the vacuum-assisted resin infusion repair methodology. © 2007 Elsevier Ltd. All rights reserved