ばね論文集
Online ISSN : 1348-1479
Print ISSN : 0385-6917
ISSN-L : 0385-6917
2021 巻, 66 号
選択された号の論文の13件中1~13を表示しています
論文
  • 山先 祥太, 高野 光司
    2021 年 2021 巻 66 号 p. 1-6
    発行日: 2021/03/31
    公開日: 2021/10/01
    ジャーナル フリー

    Mechanical properties (work-hardening and age-hardening, rigidity modulus) of the duplex stainless steels composed of different austenitic stability were investigated. The relationship between their mechanical properties and metallography such as phase fractions, α/γ component distribution, crystal orientation was discussed. The tensile strength of SUS821L1 after cold drawing at a cross-sectional reduction of 75 % is about 230 MPa higher than that of SUS329J3L and satisfies the B type standard of spring stainless steel wire. The rigidity modulus of SUS821L1 after drawing and aging is about 85 GPa. It is about 10GPa higher than that of SUS329J3L. The main factor of the high strength and high rigidity modulus of SUS821L1 after drawing and aging is suggested by the deformation-induced martensite containing supersaturated nitrogen.

  • 土屋 詩織, 高橋 宏治
    2021 年 2021 巻 66 号 p. 7-12
    発行日: 2021/03/31
    公開日: 2021/10/01
    ジャーナル フリー

    The purpose of this study is to investigate the effectiveness of laser peening (LP) on the fatigue strength of 3D additive manufactured maraging steel. First, LP was performed under several conditions and the optimum condition for improving fatigue strength were determined. Compressive residual stresses of 1100 MPa could be introduced on the surface by LP under the optimum condition. Then, bending fatigue tests were conducted using the two types of specimens; one with laser peened specimens under the optimal conditions (LP specimen) and the other without LP (Non-LP specimen). As a result, it was found that the fatigue strength of the LP specimen was about 43% higher than that of the Non-LP specimen. This result indicates that the introduction of compressive residual stress by LP improves the fatigue strength of 3D additive manufactured maraging steels. In addition, the fracture surfaces of specimens were observed and the fracture mechanism was investigated.

  • 長島 伸夫
    2021 年 2021 巻 66 号 p. 13-21
    発行日: 2021/03/31
    公開日: 2021/10/01
    ジャーナル フリー

    The nanoindentation test is the most important method for the evaluation of mechanical properties in ultra-small regions. However, the hardness value in the nano region does not always equal to the macro hardness. The reason is that when evaluating a steel material, the physical properties differ depending on the scale such as the strengthening mechanism of the steel material (dispersion / precipitation strengthening, grain refinement strengthening). In addition, the hardness is affected by the roundness of the indenter tip. Therefore, in order to establish an indentation method for the nano region, we proposed an empirical formula that uses monocrystal metal as a standard sample and converts the indentation depth into hardness. The hardness conversion of this nano region corresponds to the hardness of the macro region. Multi-scale mechanical properties were made possible by plotting hardness on the vertical axis and indentation size on the horizontal axis from the nano region to the macro region. In this paper, we describe the nanoindentation test equipment and the hardness conversion method for the nano region, and introduce examples of multi-scale mechanical characterization.

  • 堀口 禎行, 新堀 凌士, 大沢 基明
    2021 年 2021 巻 66 号 p. 23-28
    発行日: 2021/03/31
    公開日: 2021/10/01
    ジャーナル フリー

    This study examined surface texture engraved by laser irradiation in sulfuric acid solution. The Laser irradiation accelerates local corrosion in acid solution, and forms groove pattern. This process is called “Laser etching”. It shall be noted that the simple application of laser etching can merely create an entire surface corrosion. By applying passive potential, the groove depth of corrosion by laser irradiation became deeper than natural potential and area which was not irradiated by laser did not corrode. The groove depth of corrosion increased with increasing laser power and increasing scanning number of laser irradiation in 100 and 200 μm beam diameter. The groove width of corrosion decreased with increasing scanning speed of laser beam. Under the same laser power, groove width of corrosion by laser irradiation was approximately constant, but groove width of corrosion by laser in 100 μm beam diameter was smaller than 200 μm beam diameter under optimum laser power condition. From these results, tapered groove and multi grooves of corrosion can be formed by laser etching.

  • 小竹 茂夫
    2021 年 2021 巻 66 号 p. 29-37
    発行日: 2021/03/31
    公開日: 2021/10/01
    ジャーナル フリー

    In this study, from the definition of vibration manipulation function (VMF), we have derived residual-vibration-suppressed cam function for rest-to-rest motion of an undamped 2DOF oscillator by appropriately selecting the rising time of cam. At first, we utilized VMF to induce residual-vibration-suppressed cam function for an undamped 1DOF oscillator regardless of the rising time. In following stage, by numerical calculation, we determined some specific rising times of cam that can perform rest-to-rest motion for undamped 2DOF oscillator without residual vibration. The obtained cam function was a non-halting high-speed cam.

  • Atsumi OHTSUKI, Tomoyuki IWATA
    2021 年 2021 巻 66 号 p. 39-48
    発行日: 2021/03/31
    公開日: 2021/10/01
    ジャーナル フリー

    In elements used as flexible linking devices and structures, the main characteristic is a fairly large deformations without exceeding the elastic limit of the material. This property is a matter of both analytical and technological interests. Previous studies of large deformation have been generally concerned with a single member (e.g. a cantilever beam, a simply supported beam, etc.). However, there are very few large deformation studies of assembled members such as frames (e.g., a medical device: stent, a carbon nanotube structure, a fishing net, a food net, a gabion, etc.) This paper deals with a square net structure with rigid joints, loaded diagonally in either tension or compression by a pair of opposite forces. Analytical solutions such as displacements, deflection angles and bending moments for large deformation are obtained in terms of elliptic integrals, and some solutions are compared with the experimental data. The conformity of the two results is found to be fair enough. Therefore, it is inferred that this analytical theory is effective for large deformation analysis of a stent.

  • 浅見 敏彦
    2021 年 2021 巻 66 号 p. 49-58
    発行日: 2021/03/31
    公開日: 2021/10/01
    ジャーナル フリー

    There are three typical criteria used in the design of dynamic vibration absorbers (DVAs): H optimization, H2 optimization, and stability maximization. Recently, interest has shifted to the optimization of multi-mass DVAs, but in fact, in even the most basic single-mass DVA, the effect of primary system damping on the optimal solution is still not fully understood with respect to the H criterion. Exact H -optimal solution for a series-type double-mass DVA attached to a damped primary system was reported in my paper recently. This article presents the application of this H optimization method developed for a double-mass DVA to the optimization for a single-mass DVA. In the H optimization of the mobility transfer function, a highly accurate numerical solution was successfully obtained by solving a single sixth-order algebraic equation. In the case of optimization of compliance and accelerance transfer functions, it is shown that a highly accurate numerical solution can be obtained by solving ternary systems of simultaneous algebraic equations. It should be noted that the equations presented in this paper can be factorized into simpler equations when there is no damping in the primary system. It is also demonstrated herein that the factorized expressions yield the previously published H-optimal solutions.

  • 浅見 敏彦, 山田 啓介
    2021 年 2021 巻 66 号 p. 59-66
    発行日: 2021/03/31
    公開日: 2021/10/01
    ジャーナル フリー

    In most dynamic vibration absorbers (DVAs) used in practical applications, polymeric materials having energy restoring capability and damping effect are used instead of coil springs as spring elements. It is known that the damping force for such polymeric materials has hysteretic characteristics and varies in proportion to the relative displacement rather than the relative velocity between objects. This paper proposes an optimal design formula for a double-mass hysteretically damped DVA with two masses connected in series. For the design of the DVA in this study, the stability maximization criterion, which attenuates the free vibration response of the primary system in the shortest time, was adopted. It was found that the optimal design expression for installing the series-type double-mass DVA on an undamped primary system can be expressed by a very simple formula. The maximized stability index which determines the speed of vibration convergence in the double-mass DVA system was 1.7 times higher than that of the corresponding single-mass DVA. When there is damping factor in the primary system, the optimal design condition for the DVA cannot be expressed with such a simple formula, however an equation for this calculation is presented in this paper. The equation can be easily solved numerically, and the results show that the stability of the system is further increased compared to the undamped primary system.

  • 松野 孝博, 勝間 達郎, 平井 慎一
    2021 年 2021 巻 66 号 p. 67-73
    発行日: 2021/03/31
    公開日: 2021/10/01
    ジャーナル フリー

    A circular shaped soft robot is a kind of jumping robots. This robot has jumping capability when its elastic outer shell is deformed. It was confirmed that the jump height is increased when the bottom side of the circular robot was deformed to flat. The deformed shape was referred as a dish shape, and some methods were proposed to deform a circular shell to dish shape. The elastic outer shell consisting of three rings is the one of structures capable of deforming to dish shape passively. However, in previous researches, the conditions of rings deforming to dish shape was not clarified theoretically, and the adjustment of the elastic outer shell was executed experimentally. In this study, we analyzed the deformed shape of elastic outer shell with three rings. Then, the relationship between the rigidity of each ring and the deformed shape was investigated. The combination factor of flexural rigidity and torsional rigidity of the rings were derived for the suitable bottom flatness of the rings.

  • 中曽根 祐司, 川上 奏
    2021 年 2021 巻 66 号 p. 75-81
    発行日: 2021/03/31
    公開日: 2021/10/01
    ジャーナル フリー

    This study has investigated the effects of spring pitch on the principal stresses and the correction factors, Fi(i=I, II and III) of the three modes of the stress intensity factors for semielliptic surface cracks on the surface of compression coil springs both inside and outside of the coils. For this purpose, 3D finite element stress analyses have been made on compression coil springs with and without surface cracks having normalized pitch p/R=0.8, 1.2 and 1.8, or the pith angle α=7.3°, 10.8°, 16.0°, respectively where p is the spring pitch and R the coil radius. The principal stresses calculated by FEM were compared with those calculated by the formula proposed by A. M. Wahl with the pitch angle α taken into consideration. The results obtained by FEM and by the formula showed good agreement, revealing that both the maximum and minimum principal stresses σ1 (>0) and σ3 (<0) were the lowest on the wire surface inside of the coil and increased linearly with the distance from the axis of the wire and reached their maxima on the outer surface of the coil. The differences between the maximum and minimum values of σ1 and σ3 increased as the value of p/R became larger probably due to the bending stress. The correction factor FI of the mode I stress intensity factor was larger on the wire surface outside of the coil than on that inside of the coil. The maximum FI value was 0.66 outside for p/R=1.8 whereas 0.34 inside for p/R=0.8 at the eccentric angles of Φ=30° and 150°. The FI value became larger with increase in the p/R value outside whereas it became smaller with increasing p/R value inside. The FI value was found dominant among the three modes of correction factors; i.e., both the FII and the FIII values were nearly zero and slightly varied along the periphery of the crack.

  • 山脇 正人, 上杉 直也
    2021 年 2021 巻 66 号 p. 83-86
    発行日: 2021/03/31
    公開日: 2021/10/01
    ジャーナル フリー

    The measurement of positron annihilation lifetime has been used as an analytical technique for detecting ultrafine defects. It is also applicable to research on metal fatigue and the development of functional polymer materials since it exhibits high detection sensitivity for lattice defects of metals and free volume of polymers. We focused on the positron annihilation lifetime measurement as an analytical method for shot-peened materials, and developed desktop and portable type systems for in-line or on-site inspections. At this opportunity, we report an example of positron annihilation lifetime measurements for shotpeened samples and make a comparison with the full width of half maximum (FWHM) values of X-ray diffraction (XRD) measurements.

  • ばねの遅れ破壊に関する研究委員会
    2021 年 2021 巻 66 号 p. 87-95
    発行日: 2021/03/31
    公開日: 2021/10/01
    ジャーナル フリー

    The risk of delayed fracture tends to increase by increasing hardness of coil spring, and to establishing suitable and safe evaluation method test method is essential. Once the evaluation method is standardized, automotive maker and spring maker can make fair judgement based on common criteria. It is expected that spring maker can reduce evaluation cost. Previous report was to establish hydrogen analysis method to separate hydrogen occurred in the rust remained on material surface. And was to estimate maximum hydrogen content entered from automotive environment. What are the dominant factor of spring to promote hydrogen penetration caused by grinding was also discussed. This study reports experiment results to confirm an evaluation method of test piece to monitor delayed fracture by holding coil spring simulating fracture pattern in the market. This paper proposes an evaluation method using test piece to reproduce fracture pattern in the market.

  • 中尾 航, 石橋 郁弥, 根石 豊, 鈴木 章一, 松井 南帆人, 岩本 隆, 藤田 宜也, 天野 礼光, 江口 卓宏, 宮田 将晴, 澁谷 ...
    2021 年 2021 巻 66 号 p. 97-106
    発行日: 2021/03/31
    公開日: 2021/10/01
    ジャーナル フリー

    The guideline as kinetic equation of decarburizing to prevent excess decrease in fatigue strength, which is expressed as temperature the quenching starts, has been proposed from the systematic investigation on decarburizing spring steels;

    TQ = 910 + 44.7%Si - 30%Mn - 11%Cr - 15.2%Ni + 31.5%Mo - 203√%C - (%C - CS) {1 - exp (-(3.29 × 108t) / 2d exp (-(3.61 × 104) / (Th' + 273)))}

    where %M[mass%] indicates content of element M in steel, d[m] initial particle size of austenite. Referring the guideline, quenching from above the evaluated temperature, TQ can prevent excess decrease in fatigue strength the spring steel exposed to high temperature decarburizing atmosphere, whose temperature is Th'[°C] and decarburizing time is t[s], because the quenching leads to form the quench microstructure without surface ferrite layer. In the case that the exposed atmosphere is excess CO2 content, as same as the atmosphere of gas combustion furnace, the value of surface carbon content, CS[mass%] can be employed to be 0.2. Moreover, if the cooling rate is grater than 80 °C/s corresponding to the cooling rate of oil quenching, the guideline can be used to every spring steels. Similarly if temperature rise is slow, the guideline can be acceptable with modification of the term of decarburizing time to t + 0.03tr, where tr[s] is the time period of temperature rise.

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