Minimum weight

About: Minimum weight is a research topic. Over the lifetime, 2002 publications have been published within this topic receiving 28244 citations.

Optimum design of spatial structures

Abstract: : A systematic approach is presented to the optimal design of spatial frames for minimum weight subject to constraints on stress and geometry. The optimization procedures discussed are general and may be applied to structures which can be analyzed by matrix displacement or finite element methods. Two methods of mathematical programming are applied to obtain a minimum weight design. Both of these techniques require derivatives of the objective and constraint functions to improve estimates of the optimum design. In order to take full advantage of existing analysis capability, the programming techniques in this research have been assuming that such derivatives are not available.

Wing structural weight evolution with the cruise mach number of a commercial transport aircraft

Abstract: The present work performs a detailed analysis of the impact of the cruise speed of a commercial twinjet transport aircraft on its wing structural weight. The results will provide designers some guidelines for conceptual studies, when a cruise speed must be then specified. Some assumptions were made in order to conduct the proposed analysis: the fuel shall be store d in the wings only; the same fuselage was considered for all configurations, regardless of their cruise speed; and a maximum range of 3,695 nm (6,843 km). An algorithm named Asa Turbo was developed for the estimation of the initial wing configuration. By fulfilling design requirements and employing a performance calculation code, the procedure is able to calculate the corresponding lift coefficient and wing geometry parameters such as sweep angle, area, and airfoil maximum thickness, additionally providing an initial estimation for the wing structural weight according to the Torenbeek’s method. In order to better calculate the wing structural weight, a framework for wing structure preliminary design was employed. A code developed as PDWSW, which stands for Pre-Design Wing Structural Weight, was conceived to satisfy structural constraints as well as design requirements, based on load envelops and stress analyses under a Knowledge Based Engineering (KBE) environment. PDWSW outputs a minimum-weight structural configuration for a given wing planform. In order to start the weight estimation procedure, the wing conceptual -design Asa Turbo generated ten wing geometries for different cruise Mach numbers, ranging from Mach 0.75 to 0.90. All these wings were then modeled with CATIA ® and their structural design was considerably refined with the PDWSW framework. In order to utilize PDWSW, the user must define the position of the spars, ribs, and stringers and provide all preliminary dimensions of wings structure elements to obtain the minimum weight, within the required boundary safety. The numerical procedure implemented obtains the optimal number of ribs per wing box (main and trailing), the optimal number of stringers per rib bay, and optimal sizing of all structural components (skin, spars, ribs and stringers). This procedure guarantees that acceptable margins of safety and functionality requirements are fulfilled. The automation of the process is important in this particular application considering the enormous amount of data to be handled in a short period of time.

Selection of constructive solutions of car elements with small empty weight

Abstract: Purpose . The work is aimed to identify the reasons for the significantly higher coefficient of the empty weight of 1520 mm gauge cars in comparison with the freight cars in North America and to give recommendations for reducing the empty weight of freight cars. Methodology . As a methodology, a comparative evaluation of the strength, durability and stability of the minimum weight bearing structure made of various materials using the "space 1520" standards is applied. Findings . The authors found that with the use of high-strength steels the product weight can be reduced by a factor of five in comparison with the beam of steel 09G2S. If there is a welded joint in the construction, the weight of the structure will increase approximately by 2 times when calculated according to the "Norms for calculating and designing railroad cars of the Ministry of Railways of Russia, gauge 1520 mm (non-self-propelled)". And during calculations according to State Standard 33211-2013 "Freight cars. Requirements for strength and dynamic qualities" the weight increases almost 5 times and does not depend on the type of steel. Originality . It is revealed that the main criterion determining the empty weight of modern cars is the fatigue strength of the welded joint. It is shown that State Standard 33211-2013 and "Recommendations of the International Welding Institute" designate low endurance limits for high-strength steels and it is impossible to achieve the weight reduction if one adheres these recommendations. Practical value . The direction of actions to find the ways reducing empty weight of cars was developed: conditions for strength of welded joints of cars made of high-strength materials have been experimentally refined; methods for increasing the endurance of welded joints were developed; other types of connections are assumed.