Effect Of Build Orientation Research Articles

Optimal part orientation in Rapid Manufacturing process for achieving geometric tolerances

Rapid Manufacturing (RM) processes have evolved from the Rapid Prototyping (RP) paradigm and are increasingly being used to manufacture parts, tools and dies in addition to prototypes. The advantages of RP methods to produce complex shapes without the use of specialized tooling can naturally be extended to RM processes. For RM to be accepted as a mainstream manufacturing process, parts created by RM have to consistently satisfy critical geometric tolerances specifications for various features of the part. This paper investigates the relation between cylindricity tolerance, one of the key form tolerances, and part build orientation in layered manufacturing. The effect of build orientation on cylindricity error is analyzed by three methods: first by a simple analytic method, second by simulating the manufactured surface using a CAD (Computer Aided Design) file of the part and third by using an STL (Stereolithography) file. The mathematical relationship between cylindricity error and part orientation in a RM process is modeled and critical feasible regions for cylinder build orientation are calculated. A graphical technique for calculating the optimal build orientation for a part with multiple cylindrical features is also developed and presented in this paper. This method is tested and validated with the help of a test case and the results are provided in the paper.

The Effects of Orientation, Ventilation, and Varied WWR on the Thermal Performance of Residential Rooms in the Tropics

Building orientation is a significant design consideration, mainly with regard to solar radiation and wind. In predominantly hot humid regions like Malaysia which receives sunlight all year around, buildings should be oriented to minimize solar gain and maximize natural ventilation. This paper describes an investigation into the effect of building orientation in view of solar radiation absorptance of exterior wall, varied area ratio of glazed window to wall and the effect of natural ventilation on the thermal performance for residential building in tropical region. The FAJAR BAKTI building (postgraduate student residential building) which is oriented in the east west directions, and a located in USM Campus, Penang. The selected case study are two rooms, the first one is facing east direction while the other faced west. The differences in in/out door air temperature and air velocity of both rooms have been measured from the field directly using the comprehensive datalogger BABUC/M, this data have been analyzed and investigated. The results shows that east windows have more obvious effect on increasing indoor air temperature than west windows, that is applicable for ventilated or unventilated rooms.

Effects of build orientation on tensile strength for stereolithography-manufactured ASTM D-638 type I specimens

A statistical design of experiments (DOE) approach was used to determine if specific build orientation parameters impacted mechanical strength of stereolithography (SL) fabricated parts. A single platform (25.4 × 25.4-cm cross-section) on the 3D Systems Viper si2 SL machine was designed to hold 18 ASTM D-638 type I samples manufactured in different orientations. The DOE tested three factors: axis, layout, and position. Samples were fabricated parallel with the x-axis or y-axis, or 45° to both axes (called axes 1, 2, and 3, respectively). For each axis, samples were fabricated either flat or on an edge relative to the x–y plane (called layouts 1 and 2, respectively). Three samples were manufactured for each layout and axis combination, and the samples were labeled as positions 1, 2, or 3 depending on the distance from the center of the platform with position 1 being the closest to the center. The results from the statistical analyses showed that axis and position had no significant effect on ultimate tensile stress (UTS) or modulus of elasticity in tension (E). However, layout (or whether a sample was built flat or on an edge) was shown to have a statistically significant effect on UTS and E (at a 95% level of confidence). The differences between average UTS and E for each of the samples built flat and on an edge were ~3.53% (43.2 versus 44.8 MPa) and ~4.59% (763.9 versus 800.7 MPa), respectively. Because of the relatively small differences in means for UTS and E, the statistical differences between layout most likely would not have been identified without performing the multifactor analysis of variance. Furthermore, layout was the only factor that tested different orientations of build layers (or layer-to-layer interfaces) with respect to the sample part, and thus, it appears that the orientation of the build layer (layer-to-layer interfaces) with respect to the fabricated part has a significant effect on the resulting mechanical properties. This study represents one of many to follow that is using statistical analyses to identify and classify important fabrication parameters on mechanical properties for layer-manufactured parts. Although SL is the focus of this work, the techniques developed and presented here can be applied to any layered manufacturing technology producing any ASTM-type specimen with any particular material.

A study of the effectiveness of passive climate control in naturally ventilated residential buildings in Singapore

Singapore has the hot and humid climate throughout the year. Many passive climate control methods are adopted in the naturally ventilated residential buildings to help achieve thermal comfort and reduce the energy consumption of air-conditioning. A field measurement and computational energy simulations were conducted to examine the effectiveness of commonly used passive climate control methods for these buildings. The effect of building orientation, façade construction, special roof system and window shading device on indoor thermal environment and cooling load was studied. The surface temperature of external wall and indoor thermal environment was measured to analyze the façade thermal performance. The cooling load was simulated to evaluate the effectiveness of various passive climate methods. Using the special roof system as thermal buffer is the most efficient method to reduce the room cooling load.

Local Air Quality Impacts due to Downwash Around Thermal Power Plants: Numerical Simulations of the Effect of Building Orientation

One of the primary adverse environmental impacts associated with power generation facilities and in particular thermal power plants is local air quality. When these plants are operated at inland areas the dry type cooling towers used may significantly increase ambient concentrations of air pollutants due to the building downwash effect. When one or more buildings in the vicinity of a point source interrupt wind flow, an area of turbulence known as a building wake is created. Pollutants emitted from relatively low level sources can be caught in this turbulence affecting their dispersion. In spite of the fact that natural gas-fired combined-cycle power plants have lower air emission levels compared to other power plants using alternative fossil fuel, they can still create significant local air pollution problems. In this paper, local air quality impacts of a natural gas-fired combined-cycle power plant located in a coastal area are compared with those of another natural gas-fired combined-cycle power plant having identical air emissions but located in an inland area taking into account differences in topography and meteorology. Additionally, a series of scenarios for the inland site have been envisaged to illustrate the importance of plant lay-out configurations paying particular attention to the building downwash effect. Model results showed that different geometrical configurations of the stacks and cooling towers will cause remarkable differences in ambient air pollutant concentrations; thus it is concluded that when selecting a plant site, a detailed site-specific investigation should be conducted in order to achieve the least possible ambient air pollution concentrations with the given emissions.

A case study on the reduction of energy use for the heating of buildings

A computer program was developed and applied to a residential building in Shiraz, Iran. The building data were fed into the computer program, and calculated heating loads were compared with experimental data taken from this building. Ensuring that the developed software represented the main characteristics of the building, the effect of building orientation on reducing heating load was examined quantitatively. The load corresponding to the present residential building's orientation was compared with that of a South-facing orientation where the radiation through the vertical windows is minimum in summer and maximum in winter. It was found that the present orientation which is South-west, and is common for most buildings in Iran, requires 7% more energy for heating load than those constructed facing South.

Daylighting with windows, skylights, and clerestories

This paper examines the impact of several fenestration options on building space heating, cooling, and lighting loads. The use of skylights, windows, and clerestories is evaluated for a single floor commercial building, using the NBSLD-2 building energy analysis computer program, which possesses a fully integrated daylight model (DALITE). The evaluation focuses on: 1. (a) the impact of daylighting on heating and cooling energy and equipment sizing; 2. (b) the potential reduction in electric lighting energy requirements through daylight utilization; 3. (c) the relative daylighting and thermal performance of skylights, clerestories, and windows; and 4. (d) the effect of building orientation on fenestration optimization and selection. The NBSLD-2 computer procedure performs a dynamic simulation of hour-by-hour building thermal performance and energy requirements for a one-year period. The thermal and daylighting characteristics of each fenestration aperture are modeled to enable evaluation of the trade-offs associated with the use of each fenestration type. The results are correlated in the form of design guidelines to enable the preliminary design decisions to be made regarding fenestration location, type, configuration, and size. The energy calculations are presented as functions of fenestration characteristics, so that the potential energy advantages can be estimated for different fenestration designs.