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The purpose of this study was to clarify the effect of differences in wooden floor materials on walking with socks on. We conducted a walking experiment in four different model floors combining two types of floor finishing materials and two types of subflooring materials and a control floor (vinyl floor over the concrete subfloor) using surface electromyography of the lower limb and plantar pressure distribution as physiological indicators. It was found that the surface consolidated Japanese cedar, sugi (Cryptomeria japonica) wood finishing, which is uneven and non-slip, has smaller ratio of integrated electromyography (ratio of the integrated surface electromyogram for each model floor to the integrated surface electromyogram for the control) than the ceramic-coated Japanese cypress, hinoki (Chamaecyparis obtusa) wood finishing, which is smooth and slippery, and reduces the burden on the lower limbs during walking. The difference between the finished materials under the lowstiffness joist and 15-mm-thick plywood subflooring condition was smaller than under the high-stiffness 24-mm-thick plywood subflooring condition, indicating that the stiffness of the subflooring material has a secondary effect on the ratio of integrated electromyography. In the plantar pressure distribution, the ratio of entire plantar load to control was significantly higher for the surface consolidated Japanese cedar wood finishing under the joists and 15-mm-thick plywood subflooring condition, indicating that the low rigidity subflooring material makes the uneven surface consolidated Japanese cedar floor finish material more difficult to walk on. [ABSTRACT FROM AUTHOR]

The civil construction sector is one of the areas that most generates waste and consumes raw materials. To mitigate this environmental damage, is possible to use waste from other sectors to reduce raw material or by minimizing the generation of waste with materials of satisfactory durability. One of the main points to be evaluated is how such materials behave to the loads application and other mechanical stresses, and how it affects their acoustic performance. These mechanical tests usually are performed only in industrial materials. Still, the search for building performance is increasingly based on the sustainability, safety and habitability. Habitability requirements include acoustic performance, which is vital in buildings because its absence could cause stress, insomnia, hearing loss and other problems. So, this article proposes the use of EVA waste and rice husk in subfloors to decrease impact noise, replacing natural fine aggregates in the contents of 25, 50 and 75%. Compressive creep, dynamic stiffness and impact noise tests were performed. The results show that the use of both natural and artificial waste can represent gains in the efficiency of impact noise acoustic insulation for subfloors when used in larger proportions. [ABSTRACT FROM AUTHOR]

To improve a helicopter design concept, which meets structural and crashworthiness requirements, a research program is undertaken to study the energy absorption capability of a subfloor structure. In particular, crash tests are performed on the subfloor structure and on the intersection elements, which are components of the structure and can create high deceleration peak loads at the cabin floor level causing dangerous inputs to the occupants. Then the structures are analysed by a commercial explicit finite element code, PAM-CRASH, using detailed geometrical models, suitable materials models and the appropriate definition of contact forces and rivets. The analysis shows that the load-shortening diagrams present a good correlation to the experimental data and that the structural collapse predictions correspond closely to the observed behaviour during the experimental tests. Consequently the finite element analysis can be used to aid the designers in evaluating the crashworthiness of different structural concepts and can therefore be an important mean of reducing development costs. [Copyright &y& Elsevier]

This paper describes the design and testing of a shock absorber with an inward-folding composite tube that can be used as a structural component in its normal working state. Although more energy can be absorbed when the hollow of the tube is filled with composite debris, a higher load relative to the initial peak load will be produced. A variable structure based on two inclined energy absorbers was then proposed, and impact tests used to verify the reaction load calculation for two models experimentally. Results indicate that the variable structure had a greater compression ratio and a flatter load curve, demonstrating its potential for use in the struts of an aircraft cargo floor. [ABSTRACT FROM AUTHOR]