Fundamental investigation of losses of skeletal mineral in young adult human males and collaterally in young adult male pigtail monkeys /macacus nemestrima/ through immobilization for varying periods of time, coupled with a study of methods of preven

Skeletal mineral losses in young adult humans and monkeys resulting from immobilizatio

Dimpling process in cold roll metal forming by finite element modelling and experimental validation

The dimpling process is a novel cold-roll forming process that involves dimpling of a rolled flat strip prior to the roll forming operation. This is a process undertaken to enhance the material properties and subsequent products’ structural performance while maintaining a minimum strip thickness. In order to understand the complex and interrelated nonlinear changes in contact, geometry and material properties that occur in the process, it is necessary to accurately simulate the process and validate through physical tests. In this paper, 3D non-linear finite element analysis was employed to simulate the dimpling process and mechanical testing of the subsequent dimpled sheets, in which the dimple geometry and material properties data were directly transferred from the dimpling process. Physical measurements, tensile and bending tests on dimpled sheet steel were conducted to evaluate the simulation results. Simulation of the dimpling process identified the amount of non-uniform plastic strain introduced and the manner in which this was distributed through the sheet. The plastic strain resulted in strain hardening which could correlate to the increase in the strength of the dimpled steel when compared to plain steel originating from the same coil material. A parametric study revealed that the amount of plastic strain depends upon on the process parameters such as friction and overlapping gap between the two forming rolls. The results derived from simulations of the tensile and bending tests were in good agreement with the experimental ones. The validation indicates that the finite element analysis was able to successfully simulate the dimpling process and mechanical properties of the subsequent dimpled steel products

Hypervelocity impact testing of cables

The physics and electrical results obtained from simulated micrometeoroid testing of certain Skylab cables are presented. The test procedure, electrical circuits, test equipment, and cable types utilized are also explained

Design of New Cold Rolled Purlins by Experimental Testing and Direct Strength Method

New cold roll formed channel and zed sections for purlins, namely UltraBEAMTM2 and UltraZEDTM2, have been developed by Hadley Industries plc using a combined approach of experimental testing, finite element modelling and optimisation techniques. The new sections have improved strength to weight ratio by increasing the section’s strength by using stiffeners in the section webs. The European standards, Eurocode 3, use a traditional Effective Width Method to determine the strength of a cold formed steel member. However, the design of the new sections UltraBEAMTM2 and UltraZEDTM2 using this method is very complicated in calculating the effective section properties as these sections contain complex folded-in stiffeners. In addition, the incorporation of competing buckling modes such as distortional buckling can be difficult to analyse. To overcome difficulties of using Eurocode 3 or such a standard with the Effective Width Method for the design of these sections, the Direct Strength Method (DSM) is adopted for determining the section strengths. Four-point beam bending tests were carried out to determine the buckling and ultimate bending capacity of the UltraBEAMTM2 and UltraZEDTM2 sections. Results of experimental testing and Finite Element Analysis were initially used as validation for the design using the DSM. The DSM results in terms of in bending moment capacities were then compared with the experimental test results for a broader data in which the UltraBEAMTM2 and UltraZEDTM2 sections had a range of different width-to-thickness ratios. It showed an excellent agreement between test and DSM design values. It is concluded that the DSM is a powerful tool for the design and optimisation of the new cold roll formed channel and zed purlins

Finite Element Analysis of Cold-Formed Dimpled Steel Columns

Dimpled steel products are produced from the combination of an innovative dimpling process and a traditional forming process such as cold-roll forming or press-braking. The wider use of cold-formed dimpled steel members has promoted considerable interest in the local instability and strength of these members. Of particular interest is their buckling behaviour and ultimate strength capacity. However, the dimpling process produces cold-formed sections with a complex ‘dimpled’ surface topography and the ‘dimpled’ material is nonuniformly work hardened through the entire thickness. Owing to these complex issues, there are no existing methods to calculate the buckling strength of the dimpled products and validate against physical measurements. This paper presents a Finite Element analysis of the compressive behaviour of cold-formed dimpled steel columns. True stress-strain data obtained from physical tests were incorporated into nonlinear simulations of dimpled steel columns. The simulation results were compared with compression test results on dimpled channel and lipped channel columns and good agreements in both buckling and ultimate strength were obtained. It is demonstrated that the Finite Element analysis can therefore be used to analyse and design cold-formed dimpled steel columns

Acoustic Performance of Different Cold-Formed Studs in Double-Leaf Walls by Finite Element Analysis and Experiment

Cold-formed steel studs are often used in lightweight partition walls to provide structural stability but in the same time they change the acoustic performance of the whole system. The overall design of such lightweight structures for acoustic sound insulation becomes very complicated as the sound passing through stud needs to be quantified. One of the greatest challenges is to characterise the stud’s geometric effects on the sound transmission of the partition walls. This paper presents a Finite Element modelling approach and results into the acoustic performance of cold-formed studs in double-leaf walls which are placed in between a source room and a receiving room. The acoustic medium was modelled using fluid elements and the structure was modelled with conventional stress elements. The interaction between the acoustic medium and the structure was modelled in a coupled structural-acoustic analysis. An FE modelling setup which includes appropriate model parameters to be used in the structural-acoustic analysis was presented. The FE sound transmission loss of double-leaf walls using two different stud profiles was then calculated. Experimental tests complying with BS EN Standards 717 and 140 were also carried out to evaluate the FE results. It has shown that the FE results have similar trends and are in fair agreement with the experimental results; and the stud’s shape has significant effects on the sound transmission of the double-leaf walls. The FE analysis is a powerful tool and can be used as a complementary and alternative method to the laboratory tests for acoustic performance of double-leaf walls with steel studs

The Design and Development of New Cold Roll Formed Products by Finite Element Modeling and Optimisation

The design and development of new cold roll formed products can incur significant cost and the product may not be optimised for either performance or manufacture. This paper describes a new method to develop an optimum structural design of profile by cold roll forming using a combined approach of finite element analysis and optimisation techniques. To illustrate the concept, the design and development of a new channel beam and a new drain grating subjected to bending are presented. The two case studies, demonstrate how a roll formed profile may be optimised to improved structural performance through use of stiffeners and/or dimples. Improved performance of cold roll formed products is achieved by increasing the strength of the product without increasing the amount of the material used. The results of this paper clearly demonstrate an efficient and effective method and tool set to optimise design for performance and manufacture of cold roll formed products

Forecast of Future Aviation Fuels. Part 1: Scenarios

A preliminary set of scenarios is described for depicting the air transport industry as it grows and changes, up to the year 2025. This provides the background for predicting the needs for future aviation fuels to meet the requirements of the industry as new basic sources, such as oil shale and coal, which are utilized to supplement petroleum. Five scenarios are written to encompass a range of futures from a serious resource-constrained economy to a continuous and optimistic economic growth. A unique feature is the choice of one immediate range scenario which is based on a serious interruption of economic growth occasioned by an energy shortfall. This is presumed to occur due to lags in starting a synfuels program