Energy absorption device Patent

Energy absorption device in high precision gear train for protection against damage to components caused by stop load

Evaluation on crashworthiness and energy absorption of composite light airplane

[[abstract]]The main aim of this study was to explore the safety differences when using aluminum alloy and three different fiber reinforced composites as material for the cockpit and fuselage of light aircraft under crash landing. In accordance with the cockpit reduction amount stipulated by MIL-STD-1290A in which the reducing rates in all directions cannot exceed 15%, this study established the safety zones of impact speeds and impact angles. The overall safety zones of the carbon fiber reinforced composites and glass fiber reinforced composites cockpits were higher than that of the aluminum alloy cockpit by 38.56% and 32.12%, respectively. Among the four different fuselage materials, when carbon fiber reinforced composites was used as the cockpit material, except that the reducing rate for the crashing in the Y direction was slightly higher than the aluminum alloy cockpit, the reducing rate in the X direction and the inclined beam A direction during crashes were less than other materials, and the safety of its overall cockpit was also the most superior to other materials. The energy absorption capability of the aluminum alloy fuselage was better than the fuselages of all composite materials.[[notice]]補正完

Energy absorption by polymer crazing

During the past thirty years, a tremendous amount of research was done on the development of crazing in polymers. The phenomenon of crazing was recognized as an unusual deformation behavior associated with a process of molecular orientation in a solid to resist failure. The craze absorbs a fairly large amount of energy during the crazing process. When a craze does occur the surrounding bulk material is usually stretched to several hundred percent of its original dimension and creates a new phase. The total energy absorbed by a craze during the crazing process in creep was calculated analytically with the help of some experimental measurements. A comparison of the energy absorption by the new phase and that by the original bulk uncrazed medium is made

Energy absorption of composite materials

Results of a study on the energy absorption characteristics of selected composite material systems are presented and the results compared with aluminum. Composite compression tube specimens were fabricated with both tape and woven fabric prepreg using graphite/epoxy (Gr/E), Kevlar (TM)/epoxy (K/E) and glass/epoxy (Gl/E). Chamfering and notching one end of the composite tube specimen reduced the peak load at initial failure without altering the sustained crushing load, and prevented catastrophic failure. Static compression and vertical impact tests were performed on 128 tubes. The results varied significantly as a function of material type and ply orientation. In general, the Gr/E tubes absorbed more energy than the Gl/E or K/E tubes for the same ply orientation. The 0/ + or - 15 Gr/E tubes absorbed more energy than the aluminum tubes. Gr/E and Gl/E tubes failed in a brittle mode and had negligible post crushing integrity, whereas the K/E tubes failed in an accordian buckling mode similar to the aluminum tubes. The energy absorption and post crushing integrity of hybrid composite tubes were not significantly better than that of the single material tubes

Crashworthiness capability of jute and glass fibre reinforced epoxy tubes under quasi-static loading condition for automotive application

During last few years, the interest in using natural fibers as reinforcement in polymers has increased dramatically. Natural fibers are not only strong and lightweight but also relatively very cheap. This study examined the potential utilization of jute in the crash energy absorption. A combination of hand layup and vacuum bladder technique was kused to search the influence of utilizing jute fibre on crashworthiness parameters of composite materials. To improve the mechanical properties, jute fiber was hybridized with glass fiber. In this work, there are two main parts of study. Firstly, it is to investigate the effect of cross-sectional shapes, number of layers and temperature treatment on the progressive deformation of jute/epoxy composite tubes. Secondly, the suitable type of geometry was chosen to study the effect of hybrid (jute-glass/epoxy) onto the structural designs. All the tests were undergone quasi-static axial crushing of 10 mm/min. Their peak load (Pmax), mean load (Pm), energy absorption (EA) and specific energy absorption (SEA) were discussed in detail. In the study of types of five geometrical shapes (corrugated, circular, hexagonal, octagonal and decagonal cross sectional) with different number of layers (two, three and four layers). It is found that the corrugated geometric shape with three layers (RHS) gives the best energy absorption (30.92 J/g) in specific energy absorption parameter compared to other geometries used in present study. For the temperature treatment, the results showed that the post-curing by gradual temperature treatment (TT) improved the peak load by decreased with 55% as compared to similar circular specimen without temperature treatment (No TT). From the test, it is found that the substitution of one layer of jute fibre with one layer of glass fibre resulted in an improvement in the crashworthiness parameters than layers jute. The best result was obtained when hybrid jute-glass was used, where the energy absorption and specific energy absorption was improved by about 43% and 31%, respectively

Experimental and numerical study on axial crushing behaviour of pultruded composite tubes

An extensive experimental investigation was carried out to study the energy absorbing characteristics and progressive deformation behavior of unidirectional pultruded composite tubes subjected to an axial impact load. Pultruded square and circular profiles with glass-polyester and glass-vinylester combinations were used to study the specific energy absorption characteristics. Two types of triggering profiles were incorporated to investigate the effect of triggering on energy absorption. All the above combinations were investigated for three impact velocities. The effects of geometry profile, triggering and strain rate on energy absorption of composite tubes were studied in detail. A numerical simulation using finite element method was carried out to assess the energy absorption capability of composite tubes. To model the delamination between the composite plies, a new approach was adopted using cohesive elements. The progressive failure modes and crushing characteristics of the composite tubes are presented. From these studies, the composite tubes can be considered as energy absorbing members for impact applications

Electron and proton absorption calculations for a graphite/epoxy composite model

The Bethe-Bloch stopping power relations for inelastic collisions were used to determine the absorption of electron and proton energy in cured neat epoxy resin and the absorption of electron energy in a graphite/epoxy composite. Absorption of electron energy due to bremsstrahlung was determined. Electron energies from 0.2 to 4.0 MeV and proton energies from 0.3 to 1.75 MeV were used. Monoenergetic electron energy absorption profiles for models of pure graphite, cured neat epoxy resin, and graphite/epoxy composites are reported. A relation is determined for depth of uniform energy absorption in a composite as a function of fiber volume fraction and initial electron energy. Monoenergetic proton energy absorption profiles are reported for the neat resin model. A relation for total proton penetration in the epoxy resin as a function of initial proton energy is determined. Electron energy absorption in the composite due to bremsstrahlung is reported. Electron and proton energy absorption profiles in cured neat epoxy resin are reported for environments approximating geosynchronous earth orbit