Design and Fabrication of Components with Optimized Lattice Microstructures

The design and fabrication of components with optimized lattice microstructures is a new approach to creating lightweight high-performance objects. This paper introduces a unique and complete integration of design and fabrication leading to the creation of structural components with complex composite microstructures. Rather than a solid cast component with optimized outer shape this new approach leads to a component with an inner skeleton or microstructure maximizing one or more properties such as the stiffness-to-weight ratio. Three dimensional gradient materials are a natural outcome of this approach. An introduction to the design optimization and hybrid fabrication approach will be provided in addition to research progress and challenges through Spring 2004.Mechanical Engineerin

Geometry and Procedure for Benchmarking SFF and Hybrid Fabrication Process Resolution

Since the advent of SFF and RP a number of SFF benchmarking geometries and methodologies have been developed and employed with some similarities but limited standardization. Minimal information has been published in regard to a standard method of measuring the resolution limits or capabilities of SFF and SFF-based hybrid processes. In an effort to benchmark resolution limits of SFF and Hybrid Fabrication processes, several benchmarking geometries were developed to capture the resolution capabilities, specifically hole size and rod size range, of multiple hybrid fabrication path steps and a hybrid path as a whole. These useful geometries are shared with the SFF community and procedures for their use are described in this paper.Mechanical Engineerin

Statistical Process Control For Solid Freeform Fabrication Processes

Statistical prpcess control (SPC) has not been widely used for solid freeform fabrication (SFF) pr~cesses, primarily due to the wide diversity ofgeometries in builds. In addition, typical parts created on SFF platforms are not ofsimple, nor easy-to- measure geometries, which fVrther complicates the application ofSPC. A study is currently in progress to establisq a method to apply SPC to SFF. Three SPC test parts were studied to determine the addedIbuild cost and accuracy improvement when SPC is applied to stereolithography. In this study, SPC was applied to X & Y shrinkage, and line-widthcompensation facto~s over a period oftime. IfSPC can be effectively applied, it will alert the operator to othe~seunnoticed system changes before valuable build-time is lost.Mechanical Engineerin

Indirect Rapid Molds for Prototype Lost-Foam Pattern Production 506

Lost-foam (also known as Expendable Pattern Casting, EPC) is an ever-growing metalmcasting technique, capable of producing complex metal components without parting lines. Mold preparation for lost-foam casting is typically accurate, but expensive and slow. The goal of this research was to develop a new approach for producing rapid lost-foam molds. With this new approach, patterns generated by SFF technology are used to form indirect composite lost-foam molds. Ultimately, our objective is to produce these molds quickly, accurately, and inexpensively. This new approach to lost-foam mold-making will be explained as well as the results of one trial.Mechanical Engineerin

Custom, Integrated, Pneumatic, Rotary Actuator for an Active Ankle-Foot Orthosis

End-use objects produced via additive manufacturing (AM) are on the rise and new applications in the fluid power industry are emerging. Recently, a custom, pneumatic, rotary actuator was been designed and additively manufactured for integration into an active ankle-foot orthosis that is being developed in the National Science Foundation’s Center for Compact and Efficient Fluid Power. All necessary plumbing, between the valves and vanes, is integrated into the additively-manufactured housing of the actuator; and, the silicone translating seals were vacuum-transfer molded using additively-manufactured molds and inserts. This nonconventional actuator has more theoretical torque, and weighs less, than the off-the-shelf component that it replaced. Further development will reduce seal leakage, and optimize designs for additional mass reduction. Results-to-date are presented, in addition to several other examples of the growing use of AM in the fluid-power industry.Mechanical Engineerin

Synthesis of a Compact Tetralattice Heat Exchanger using Solid Freeform Fabrication and Comparison Testing Against a Tube Heat Exchanger

The challenge for Solid Freeform Fabrication (SFF) lies in fabricating complex parts that are not possible by conventional manufacturing means. The goal was to apply SFF techniques to complex geometry heat exchangers. The heat exchanger structure is modeled after the covalently bonded carbon atoms of a diamond. The tetrahedron diamond lattice, or Tetralattice, is a repeating lattice unit that forms a network of channels to form the heat exchanger. Electroforming methods creating Tetralattice were applied to synthesize an air-oil compact heat exchanger. After production, the heat exchanger was tested and compared with an industry standard heat exchanger for performance evaluation.Mechanical Engineerin

Fabrication of Custom Dynamic Pedorthoses for Clubfoot Correction via Additive-Based Technologies

Additive technologies have created many opportunities to improve the quality of life for patients in a range of medical applications. This paper provides an overview of how several of these technologies were leveraged to transform custom pedorthosis designs into physical, end-use, custom pedorthoses for clubfoot patients. The pedorthoses that were produced are currently being tested on the respective patients for their improvement in mobility and degree of clubfoot correction, and will continue through early 2010. The advantage of this approach is the reduction in labor and the increase in degrees of design freedom available, compared to conventional methods of fabricating orthotic devices. Several new approaches for fabricating custom orthotic devices that were explored, and the related results, are discussed.Mechanical Engineerin

Geometry and procedure for benchmarking SFF and hybrid fabrication process resolution

ABSTRACT Since the advent of SFF and RP a number of SFF benchmarking geometries and methodologies have been developed and employed with some similarities but limited standardization. Minimal information has been published in regard to a standard method of measuring the resolution limits or capabilities of SFF and SFF-based hybrid processes. In an effort to benchmark resolution limits of SFF and Hybrid Fabrication processes, several benchmarking geometries were developed to capture the resolution capabilities, specifically hole size and rod size range, of multiple hybrid fabrication path steps and a hybrid path as a whole. These useful geometries are shared with the SFF community and procedures for their use are described in this paper

Antimicrobial Activity of two Mentha Species Essential Oil and its Dependence on Different Origin and Chemical Diversity

Genus Mentha presents group of plants which are the most studied in family Lamiaceae. Aboveground parts are used for different purposes in pharmacy, food industry or confectionery. Most important is natural product extracted from leaves - essential oil (EO). The aim of presented experiment was to demonstrate different chemotype and compare antibacterial activity of two Mentha species EO. Plant samples were obtained from various environments – from Slovakia and from Italy. Dominant compounds were determined by GC/MS. The results showed high amount of menthol and menthone in tested Slovak peppermint EO. On the other hand, carvone and 1,8-cineole were determinate as dominant compounds in Italian spearmint EO. The antimicrobial activity of the EO was investigated by disc diffusion and broth micro dilution methods. EO was evaluated for their antibacterial activity against 7 microorganisms: Enterobacter cloacae, Salmonella spp., Klebsiella pneumoniae, Escherichia coli, Staphylococcus aureus, Streptococcus pyogenes. The determination results of antibacterial activity by agar disk diffusion method ranged from 7 to 14 mm of the growth inhibition zone. MIC of tested mint EO varied from 0.625 to 2.5 μg/mL. In addition, both EO showed relatively the same antibacterial activity against the selected Gram-negative bacteria. However, there is a variation in the antibacterial activity against Gram-positive bacteria

Similarity and differences in elderly patients with fixed airflow obstruction by asthma and by chronic obstructive pulmonary disease.

SummaryBackgroundEpidemiologic studies have demonstrated that elderly patients with fixed airflow obstruction can be affected by asthma or chronic obstructive pulmonary disease (COPD).MethodsWe studied 49 consecutive elderly outpatients, presenting fixed airflow obstruction, by clinical history (smoking), pulmonary function tests, blood gas analysis, and induced sputum.ResultsThe age was not different in patients with COPD (n=28) and asthma (n=21) (70.2±3.9 years vs. 69.6±3.7 years), also the degree of fixed airflow obstruction was similar (FEV1: 58.3±1.5% vs. 59.0±1.4% of predicted). Patients with asthma had significantly more eosinophils in peripheral blood (0.43±0.05×10−3μL vs. 0.27±0.1×10−3μL, P<0.0001), and in induced sputum (5.0% [(p25th and p75th) 5.0–6.0%] vs. 1.0% [(p25th and p75th) 0.01–1.0%]; P<0.0001), as well as serum ECP (18.6±4.9ng/mL vs. 7.7±4.7ng/mL, P<0.0001) and ECP in the induced sputum (31.6±2.9ng/mL vs. 5.6±4.9ng/mL, P<0.0001). Finally, in induced sputum the eosinophils EG2+ were higher in patients with asthma than in patients with COPD (40.5 [(p25th and p75th) 39.3–44.3] MFI vs. 3.9 [(p25th and p75th) 0–11.4] MFI, P<0.0001). They also had significantly higher diffusing capacity, and a greater reversibility to steroids, after 14-day course of therapy, whereas the reversibility to 400μg of salbutamol was similar.ConclusionDespite similar fixed airflow obstruction, elderly patients with asthma have distinct characteristics compared with patients with COPD