Minimum Weight of Tapered Round Thin-Walled Columns

1952 ◽  
Vol 19 (3) ◽  
pp. 375-380
Author(s):  
Morris Feigen
Keyword(s):  
Wall Thickness ◽  
Minimum Weight ◽  
Weight Ratio ◽  
Optimum Shape ◽  
Bending Stress ◽  
Round Tube ◽  
Cylindrical Column ◽  
Truncated Cone ◽  
Thin Walled ◽  
Tapered Column

Abstract It is shown that the optimum wall thickness of a cylindrical round tube column is a function of load only and is independent of diameter. The optimum wall thickness of a tapered round thin-walled column is found to be constant along its length. The optimum shape of a tapered round thin-walled column is derived, being that column whose bending stress in the buckled state is constant along its length. The weight ratio of the optimum tapered column to an equal-strength optimum cylindrical column is found to be 0.8924. It is shown that a double truncated cone whose diameter ratio is in the range 0.35 ⩽ D1/D2 ⩽ 0.50 closely approaches the optimum column. If it is specified that no portion of the double truncated cone shall yield, then the weight advantage of the cone over the cylindrical column is rapidly lost as the stress in the cylindrical column approaches the yield stress. In the inelastic range the weight advantage of the tapered column will be less than in the elastic range.

Imperialist Competitive Algorithm for Multiobjective Optimization of Ellipsoidal Head of Pressure Vessel

2011 ◽  
Vol 110-116 ◽  
pp. 3422-3428 ◽  
Author(s):  
Behzad Abdi ◽  
Hamid Mozafari ◽  
Ayob Amran ◽  
Roya Kohandel
Keyword(s):  
Genetic Algorithm ◽  
Pressure Vessel ◽  
Shear Force ◽  
Minimum Weight ◽  
Bending Moment ◽  
Imperialist Competitive Algorithm ◽  
Optimum Shape ◽  
Working Pressure ◽  
Competitive Algorithm ◽  
Bending Stresses

This work devoted to an ellipsoidal head of pressure vessel under internal pressure load. The analysis is aimed at finding an optimum weight of ellipsoidal head of pressure vessel due to maximum working pressure that ensures its full charge with stresses by using imperialist competitive algorithm and genetic algorithm. In head of pressure vessel the region of its joint with the cylindrical shell is loaded with shear force and bending moments. The load causes high bending stresses in the region of the joint. Therefore, imperialist competitive algorithm was used here to find the optimum shape of a head with minimum weight and maximum working pressure which the shear force and the bending moment moved toward zero. Two different size ellipsoidal head examples are selected and studied. The imperialist competitive algorithm results are compared with the genetic algorithm results.

An Elementary Theory of the Bourdon Gage

1946 ◽  
Vol 13 (3) ◽  
pp. A207-A210
Author(s):  
Alfred Wolf
Keyword(s):  
Wall Thickness ◽  
Maximum Stress ◽  
Transverse Section ◽  
Elementary Theory ◽  
Thin Walled ◽  
Longitudinal Extension

Abstract A theory of the Bourdon gage is presented based upon two elements of strain, namely, the bending of the walls in a transverse section through the gage tubing, and a longitudinal extension parallel to the axis of the tubing. Practical formulas are derived for the calculation of the sensitivity and the torque of the Bourdon gage. An estimate is made of the maximum stress. The sensitivity of a very thin-walled gage is shown to be proportional to the inverse first power of the wall thickness. Results of a few measurements show agreement with the theory.

Minimum Weight Design of Thin–walled Cells in Torsion

1955 ◽  
Vol 59 (530) ◽  
pp. 120-126 ◽  
Author(s):  
V. Cadambe ◽  
S. Krishnan
Keyword(s):  
Structural Design ◽  
Necessary Conditions ◽  
Minimum Weight ◽  
Local Buckling ◽  
Design Criteria ◽  
Minimum Weight Design ◽  
Weight Design ◽  
Uniform Wall ◽  
Thin Walled ◽  
Twisting Deformation

The minimum weight approach to structural design was introduced by F. R. Shanley with reference to narrow and wide columns and shells subjected to bending, and was later dealt with more comprehensively in a book by the same author. This was further extended to structures like tapered round thin-walled columns and frames. In this paper expressions giving optimum sectional dimensions for long thin walled cells of circular, semi–circular, rectangular and triangular shapes and uniform wall thickness have been derived. The design criteria used to obtain the minimum necessary conditions are (1) failure by local buckling and (2) a limit on the twisting deformation of the cells. Working curves from which the optimum sectional dimensions can be read for given torque and limiting twist have been plotted. And finally, a method of approach to the problem of combined bending and torsion has also been indicated.

scholarly journals Design and Assessment of a Lightweight Polymer Concrete Utility Manhole

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Luciano Leonardi ◽  
Teresa M. Pique ◽  
Tomas Leizerow ◽  
Humberto Balzamo ◽  
Celina Bernal ◽  
...  
Keyword(s):  
Portland Cement ◽  
Wall Thickness ◽  
Chemical Resistance ◽  
Mechanical Performance ◽  
Minimum Weight ◽  
Polymer Concrete ◽  
Portland Cement Concrete ◽  
Epoxy Amine ◽  
Amine System ◽  
Typical Soil

Polymer concrete is a composite using polymer instead of portland cement as a binder. It allows optimizing the tensile and cracking strength and the chemical resistance of a concrete structure. In this study, different formulations were assessed in order to optimize a polymer concrete underground utility manhole with minimum weight. Formulations were based on an epoxy-amine system mixed with fine regular-weight aggregates and ultralightweight aggregates. The objective was to design and assess an underground utility structure with the epoxy chemical resistance, strength, and lightweight and to study whether the replacement of regular-weight aggregates by ultralightweight aggregates would contribute to improve the strength and reduce the structure weight. Two polymer concrete systems were designed from its formulation, and their mechanical performance was evaluated experimentally. A numerical model was developed for a polymer concrete underground utility structure made from the different formulations. It was simplified as a box subjected to typical soil loads. The size of the box is a standard one. Its minimum wall thickness is specified for sustaining the in-use service pressures obtained from numerical simulation. The model predicted that the epoxy/regular-weight aggregate formulation could be used with a wall thickness significantly smaller than the formulation with ultralightweight aggregates. In addition, the underground utility structure made with this formulation would weigh six times less than the same box made with a traditional portland cement concrete.

A Novel Omnidirectional Self-Locked Energy Absorption System Inspired by Windmill

2020 ◽  
Vol 87 (8) ◽  
Author(s):  
Yizhe Liu ◽  
Feng Xiong ◽  
Kuijian Yang ◽  
Yuli Chen
Keyword(s):  
Energy Absorption ◽  
Absorption Efficiency ◽  
Absorption System ◽  
Tube System ◽  
Round Tube ◽  
Action Mode ◽  
Energy Absorption Efficiency ◽  
Thin Walled Tube ◽  
Thin Walled ◽  
Shed Light

Abstract Impact accidents cause great damage to lives and properties because the destructiveness, direction, and action mode of impact loadings can hardly be predicted. Ordinary thin-walled tube systems for energy absorption require outside constraints or inside fasteners to avoid tube splashing, which affects the modifiability of the systems and limits their application in emergencies. In an effort to break through this limitation, inspired by windmill, a novel omnidirectional self-locked energy absorption system has been proposed. The proposed system is made up of thin-walled tubes with windmill-liked cross section, which are specially designed to interlock with adjacent tubes and thus provide constraints among individual tubes to resist impact loadings in spatial arbitrary directions. The spatial omnidirectional self-locking capability of the windmill-inspired system is demonstrated under distributed and concentrated impact loadings. Moreover, the windmill-inspired system shows higher energy absorption efficiency than that of the widely used round tube system and previous self-locked system under loadings in various directions, and their energy absorption properties can be further improved by combining with the round tube system, adjusting the geometric parameter of each tube and designing the arrangement of tubes with different properties in the system. This work may shed light on the energy absorption system design and expand the application of self-locked energy absorption systems.

Note on the Minimum-Weight Design of Thin-Walled Cells in Combined Bending and Torsion

1956 ◽  
Vol 60 (541) ◽  
pp. 65-66 ◽  
Author(s):  
V. Cadambe ◽  
S. Krishnan
Keyword(s):  
Minimum Weight ◽  
Bending Moment ◽  
Rational Approach ◽  
Pure Torsion ◽  
Minimum Weight Design ◽  
Weight Design ◽  
Thin Walled

In a recent paper the authors suggested that the minimum weight design of thin-walled cells in combined bending and torsion could be tackled by using the well-known concept of equivalent bending moment and torque. It is now felt that a more rational approach would be to base the analysis on the buckling behaviour of the walls of the cell under combined compression and shear and choose the dimensions such that the cell will just resist buckling. The second criterion for design is taken as a limit on the twist as adapted in the case of pure torsion. Two types of sections, rectangular and circular, are discussed in this note.

scholarly journals OPTIMUM PERFORMANCE OF GREEN MACHINING ON THIN WALLED TI6AL4V USING RSM AND ANN IN TERMS OF CUTTING FORCE AND SURFACE ROUGHNESS

2019 ◽  
Vol 81 (6) ◽  
Author(s):  
Muhammad Yanis ◽  
Amrifan Saladin Mohruni ◽  
Safian Sharif ◽  
Irsyadi Yani
Keyword(s):  
Surface Roughness ◽  
Cutting Force ◽  
Cutting Speed ◽  
Weight Ratio ◽  
Cutting Fluid ◽  
Depth Of Cut ◽  
Ann Model ◽  
Green Machining ◽  
Radial Depth ◽  
Thin Walled

Thin walled titanium alloys are mostly applied in the aerospace industry owing to their favorable characteristic such as high strength-to-weight ratio. Besides vibration, the friction at the cutting zone in milling of thin-walled Ti6Al4V will create inconsistencies in the cutting force and increase the surface roughness. Previous researchers reported the use of vegetable oils in machining metal as an effort towards green machining in reducing the undesirable cutting friction. Machining experiments were conducted under Minimum Quantity Lubrication (MQL) using coconut oil as cutting fluid, which has better oxidative stability than other vegetable oil. Uncoated carbide tools were used in this milling experiment. The influence of cutting speed, feed and depth of cut on cutting force and surface roughness were modeled using response surface methodology (RSM) and artificial neural network (ANN). Experimental machining results indicated that ANN model prediction was more accurate compared to the RSM model. The maximum cutting force and surface roughness values recorded are 14.89 N, and 0.161 µm under machining conditions of 125 m/min cutting speed, 0.04 mm/tooth feed, 0.25 mm radial depth of cut (DOC) and 5 mm axial DOC. 

Optimal Design of an Elastic Column of Thin-Walled Cross Section

1968 ◽  
Vol 35 (2) ◽  
pp. 285-288 ◽  
Author(s):  
N. C. Huang ◽  
C. Y. Sheu
Keyword(s):  
Optimal Design ◽  
Cross Section ◽  
Wall Thickness ◽  
Cross Sections ◽  
Unit Length ◽  
Compressive Load ◽  
Median Line ◽  
Vertical Column ◽  
Thin Walled ◽  
Allowable Compressive Stress

This paper treats the optimal design of a vertical column that is built-in at the lower end. In addition to its own weight, the column is to carry an axial compressive load at its unsupported upper end. The column is to be designed as a thin-walled tube. The median line is to be the same for all cross sections; the wall thickness, though constant along the median line of any cross section, is allowed to vary along the length of the tube. Accordingly, the weight per unit length of the tube is proportional to the bending stiffness. For given length and total weight, the variation of the wall thickness along the column is to be determined to maximize the critical value of the compressive load at the upper end. The influence of a maximum allowable compressive stress on the design is also investigated.

scholarly journals Investigation of an inverse thermal injection mould design methodology in dependence of the part geometry

2021 ◽  
Author(s):  
C. Hopmann ◽  
J. Gerads ◽  
T. Hohlweck
Keyword(s):  
Wall Thickness ◽  
Injection Moulding ◽  
Thermal Design ◽  
Internal Stresses ◽  
Cooling Channel ◽  
Injection Mould ◽  
Compression Moulding ◽  
Compression Pressure ◽  
Injection Moulding Process ◽  
Thin Walled

AbstractThe production of injection moulded components with low shrinkage and warpage is a constant challenge for manufacturers. The thermal design of the injection mould plays an important role for the achievable quality, especially the placement of the cooling channels. This design is usually based on empirical knowledge of the mould designers. The construction is supported iteratively by injection moulding simulations. In the case of thick-walled plastic optics with big wall thickness jumps, the shrinkage is compensated by injection compression moulding. In this process, the thin-walled areas freeze earlier and the necessary compression pressure introduces stresses into these areas which reduces the optical performance. An adapted cooling channel design can reduce these problems. At the IKV, Institute for Plastics Processing in Industry and Crafts at the RWTH Aachen University, a methodology was developed which inversely calculates the cooling requirement of the moulded part A demand-oriented cooling channel system is derived based on the computed results. The aim of the research projects is to minimise displacement and internal stresses by temperature control of the moulded parts according to the demand. In this paper, the methodology is applied to three different geometries, representing three classical parts for the injection moulding process. Three different quality areas in the mould for the inverse optimisation are defined and investigated. For each geometry the cooling channel designs are then validated in injection moulding simulations based on the results from the thermal optimisation. It can be shown that for different component geometries and thicknesses, different quality areas are advantageous and decrease the maximum warpage of the parts. For thin-walled ribbed components, a 2D approach leads to a 15% smaller displacement, for components with wall thickness jumps, all investigated quality ranges show no differences in displacement, but a surface in the middle of the part is preferred due to a 3 °C lower standard deviation of the temperature distribution.

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