T he behavior of an infi nitely long flexib le fil a men t after transverse impact is treated theoret.icall y. The fil a ment is ass u med to have a tension-strain curve that is always co ncave dow nward, and to have no short-ti me creep or stress-rei fixation effects. Under most cond itions the impact in itiates a varia bl e strain t hat prop agates down the fil a ment between an "elasLic wave" fro nt a nd a " plastic wave" front. A tra nsverse wave, shaped li ke an inverLed V, then travels in t he co nstan t-strain region behin d the plastic-wave front. Under specia l condi tio ns t he transverse-wave front may propagate faster than the plastic-wave front, b ut the sh ape of t he tra nsverse wave r ema ins t he sam e. T he theory for both cases is worked out in d etail , an d some ill ustrative examples arc given.

The behavior of an infinitely long flexible filament after transverse impact is treated theoretically. The filament is assumed to have a tension-strain curve which is always concave downwards and to have no short time creep or stress relaxation effects. Under most conditions the impact initiates a variable strain that propagates down the filament between an "elastic wave" front and a "plastic wave" front. A transverse wave, shaped like an inverted "V," then travels in the constant strain region behind the plastic wave front. Under special conditions the transverse wave front may propagate faster than the plastic wave front, but the shape of the transverse wave remains the same. The theory for both cases is worked out in detail and some illustrative examples given.

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Due to its good biocompatibility, porous titanium is an interesting material for biomedical applications. Bone tissue can grow inside the porous structure and maintain a long and stable connection between the implant and the human bone. To investigate its long term stability, the mechanical behavior of porous titanium was tested under static and dynamic conditions and was compared to human bone tissue. A promising application of this material is the coating of dental implants. A manufacturing technique was developed and implants were produced. These implants were fatigue tested according to modified ISO 14801 and the micro structural change was examined. The fatigue test was statically modeled using finite element analysis (FEA). The results show that the implants resist a continuous load which is comparable to the loading conditions in the human jaw. The experiments show that the porous titanium has bone-like mechanical properties. Additionally the porous titanium shows an anisotropic behavior of its mechanical properties depending on the alignment of the pores. Finally, other potential applications of porous titanium are outlined.

If a textile yarn segment, clamped at each end, is impacted transversely at the mid point, the stress-strain curve for this yarn can be obtained from measurements on a high speed photographic record of the yarn's motion. This paper describes the apparatus and procedure used. Stress-strain curves for high rates of straining, of the order 5000%/sec., obtained by this method are given for high tenacity nylon, Fortisan, and Fiberglas. Comparison with stress-strain data obtained at conventional rates shows that these mate rials have higher initial moduli, and that their stress-strain curves remain linear up to higher stress values, when the testing rate is high. The breaking tenacities are slightly greater and breaking elongation slightly smaller at these high test rates.