This paper describes the tensile impact properties of IN Steel which have been lately developed by the Ishikawajima-Harima Heavy Industries Co., Ltd.,
By using a high speed impact tensile testing machine with a large rotary disk installed at Tokyo Institute of Technology, the authors have obtained some results from the experiment.
The impact velocity was varied from static region to 80m/s, and the test was performed at room temperature.
The results obtained are summarized as follows:
[1] Test results of the plain test pieces;
(1) The impact tensile strength of IN Steel increased up to the impact velocity of 5m's and thereafter it was almost constant regardless of the impact velocity.
(2) The maximum value of impact energy per unit volume of plain test pieces (d=8mm, l/d=5) was about 40kg·m/cm³ at the impact velocity of 40m/s.
(3) The observed critical impact velocity was about 50m/s regardless of the gauge length of test pieces.
(4) The contraction percentage of area decreased a little at the impact velocity of 5m/s, and thereafter it was not affected much by the value of impact velocity. It was about 80 percent.
[2] Test results of the notched test pieces;
(1) The impact tensile strength of notched test pieces was 60% larger than that of the plain test pieces and it was kept unchanged in the test until 20m/s of the impact velocity, but increased remarkably from that velocity up to 80m/s.
(2) As the radii of curvature at the root of the notch is smaller, the impact tensile strength somewhat increased, but the value of impact energy per unit area was kept unchanged.
(3) If the diameter of notched test pieces and radii of curvature were constant, the impact tensile strength and the value of impact energy per unit area were kept unchanged, even if the outer diameter varied D/d=1.75, 1.875 and 2.125.
(4) On the effect of the size of notched test pieces, having similar shapes, the smaller ones in size had larger impact tensile strength, but the value of impact energy per unit area showed a reversal tendency.
Generally speaking, it may be concluded that IN Steel provides excellent mechanical properties against high speed impact loading.

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The present writers have investigated about the property of fatigue damage of hard drawn steel wire and the fatigue property under double repeated bending stress in two stress levels. For the testing materials, 0.6% carbon steel wires drawn with three reductions of 25%, 50% and 85% were used and their diameters were 2.5mm.
The principal results of this investigation can be summarized as follows:
(1) When the 10% over primary stress is loaded to lower cycles than the maximum cycle of no fatigue damage n_d, the fatigue limits of wires drawn with reductions of 50% and 85% increase slightly. And when that primary stress is loaded to higher cycles than n_d, the fatigue limits of all wires decrease and those decrements decrease with the increase of the reduction by drawing.
(2) When the 10% over primary stress is loaded to lower cycles than n_d, the cumulative cycle ratio Σ(n/N) exceeds unity in both cases of secondary stress is larger and smaller than primary stress. And when that primary stress is loaded to higher cycles than n_d, the cumulative cycle ratio exceeds unity or nearly equals unity.
(3) When the 50% under primary stress is loaded to 10⁶ or 10⁷ cycles, the fatigue limits of all wires increase slightly and those increments increase with the increase of the reduction by drawing.

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As the Miner's cumulative-damage theory that the fatigue fracture will occur at Σ(n/N)=1 does not coincide with the test results for the fatigue life under varying stress amplitude in two stress levels, the present writers have presented a correctional equation which is conducted by the test result for fatigue damage.
From the result obtained in the previous report that the maximum cycle ratio of no fatigue damage decreased as the excess ratio of overstress increased, we consider that the degree of the effect of oversteress on the fatigue life is inversely proportioal to the maximum cycle ratio of no fatigue damage for that overstress. With this conception of fatigue damage, assuming that the primary stress decreases the fatigue life for the secondary stress at the ratio of n₁/N₁·i_d2/i_d1, we present the following equation for the fatigue life.
α·n₁/N₁+β·n₂/N₂=1
α=i_d2/i_d1, β≤1
where i_d1 and i_d2 are respectively the maximum cycle ratio of no fatigue damage for primary and secondary stress. β is the function of the stress level of primary stress and secondary stress and the cycle ratio of primary stress, etc..
With this correctional equation, the results obtained in the previous report on the fatigue life under double repeated stress in two stress levels are graphically elucidated.

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In this paper, the relations between Charpy impact strength (Absorbed energy/area under notch) and shape of V-notched test bar of unplasticized P.V.C. are described. The results obtained are summarized as follows:
(1) Charpy impact strengths are not varied by the deviation of the width, the thickness and the notch angle of test bar in the range of experiment.
(2) But they are varied by the deviation of the notch depth and the notch radius.
(3) The quantitative values of error of impact strength which are introduced by these deviations are shown on Table I.

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The complex strain-optical coefficient K^*, complex stress-optical coefficient M^*, complex modulus of elasticity E^* and the corresponding loss tangent of phase angles between the stress, strain and birefringence have been measured for several high polymers in the frequency range from 0.001 to 10 cycles per second. Frequency and temperature dependences of the dynamic optical properties of vulcanized Hevea rubber are very similar to those of the dynamic mechanical properties. On the other hand, the dynamic optical properties of polyethylene and polypropylene show remarkable dispersions in the above frequency range. The dynamic optical behavior of these three materials are very typical and are quite different from each other. The differences have been explained by considering different frequency dependences of three kinds of deformation mechanism, namely, orientation of molecules in amorphous region, deformation of spherulites, and orientation of crystals.

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