Transactions of Japan Society of Spring Engineers

Analysis of Coil Springs using Joint Elements

Masayoshi SHIMOSEKI, Yukio SADAKUNI

1987 Volume 1987 Issue 32 Pages 1-10
Published: March 31, 1987
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1987.1

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The problems in design and application of coil spring for suspension are considered eventually, except the dynamic problems, load characteristics, stress calculation, central bend and hammering noise. These problems come to the evaluation of end turn and treatment of the contact between coils. This papar describes that these problems can be analyzed by the finite element method using the joint elements. This analysis is also applicable comprehensively, by means of examples, to the problems of linear and non-linear forms, paralled and non-parallel compressions and elastic-plastic compression.

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Dynamical Analysis of Coil Spring by Finite Element Method

Yukio SADAKUNI, Masayoshi SHIMOSEKI

1987 Volume 1987 Issue 32 Pages 11-18
Published: March 31, 1987
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1987.11

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In application of the finite element method to analyze the vibration of coil spring, analysis is possible even on the personal computer level in accordance with a straight beam element. In the free vibration problem, natural frequency and vibration made of torsional vibration and bending vibration in addition to lengitudinal vibration are obtained in the practical accuracy. Moreover, for the forced vibration, an example of analysis is mentioned.

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Load Cell Method for Buckling Analysis of Coil Springs

Katsuhide KOHTARI, Hiroshi KATSUNO, Taro UCHIYAMA, Shiroh HISAJIMA, Ta ...

1987 Volume 1987 Issue 32 Pages 19-23
Published: March 31, 1987
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1987.19

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Buckling load of helical compression springs can be calculated by treating them as elastic columns of equivalent compressive, flexural and shearing rigidities which vary with compression of them. If the compressive load is kept under the critical one, the axis of ideal coils remains straight, and it suddenly deflects to the lateral direction when the load reaches the critical value. But compression springs usually have initial imperfections, such as initial deflection of the coil axis and end turns which cause eccentricity of loading. Therefore, the axis deflects laterally with increasing the axial compressive load under the critical one, which is a characteristic of the imperfect columns.
This paper shows a modified Southwell's method to estimate the buckling load of the perfect springs from the experimental relations between the compressive load and the fixed end moment which are detected by the multicomponents load cell. The compression tests were carried out on the coil springs of the slenderness ratio between 6 to 9.
The experimental results show good agreement with the buckling load calculated by the Haringx's theory.

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Effect of Spring Index on Set at High Temperature of Coil Spring

Noriyuki SAITO, Masami ASHINO, Kenji TAKAHASHI

1987 Volume 1987 Issue 32 Pages 24-30
Published: March 31, 1987
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1987.24

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There are various data on the set at high temperature of coil spring, however, the literature concerning the influence of spring index is less. The reporters have carried out a thghtening test at high temperature to clarify the effect of spring inde & affecting the set at high temperature. In the test, the reporters have investigated the effect of pitch angle and shot peening in addition to the spring index.
The result indicates that it is adequate not to consider the effect of spring index to the evaluation of set at high temperature.
Introduction of an empirical formula was carried on to evaluate the set at high temperature of spring effectively.

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Effect of Multistage Shot Peening on Fatigue Strength

Hideo TOSHINO, Kimihiko SHIGENO, Nobuo TAKAGI

1987 Volume 1987 Issue 32 Pages 31-34
Published: March 31, 1987
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1987.31

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Spring, such as valve spring, which are requested for higher fatigue strength, are usually shot peening to get more advancement in its fatigue strength.
One of the main factors to get higher fatigue strength by shot peening is to create the compressed residual strees.
But we must take care of the point. By the conventional shot peening, it is quite natural to get the lower compreessed residual stress around the surface of wire.
In this paper is examined a method to obtain distribution of the compressed residual stress of sufficients surface value and depth, by combining the plural shot peenings of differest strengths with the heat treatment. The result confirms the increase of fatigue strength.

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Wire Spring Fractures-Configurations and Countermeasures

Nobuharu TAKENOSHITA, Kimijiro SHIRABE, Yoshimitsu AOKI

1987 Volume 1987 Issue 32 Pages 35-43
Published: March 31, 1987
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1987.35

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There are many properties required in wire springs and the most important is that the spring must be cagable of maintaining its elasticity for a long period of time. Nevertheless, fractures in wire springs caused by a variety of factors are not uncommon, and as a manufacturere of steel wire for mechanical springs, we have many opportunities to analyze such fractured springs. This report is a summary of the results of th spring fracture analyses which we have carried out, and herein we have attemped to classify the configurations and causes of such fractures, especially for cold-coiled helical springs, and to offer some preventive measures.

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Development of GFRP leaf Spring

Yasuo ARAI, Shuji HIROMOTO, Tadataka NAGAOKA

1987 Volume 1987 Issue 32 Pages 44-51
Published: March 31, 1987
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1987.44

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In accordance with the material characteristics of GFRP, characteristics of practised GFRP leaf spring (transversal leaf spring) and the problems particular to FRP, GFRP leaf spring (parallel leaf spring) for samll-sized truck was designed and manufactured for trial in order to perform the bench test evaluation and real vehicle test evaluation (performance), by which the following points were found:
1. The following design standard can be applied to GFRP leaf spring in consideration of the material characteristics including enviromental characteristics:
Max, design stress 60kgf/mm²
Modulus of bending 4350kgf/mm²
Max, working temperature 70°C
Note: Specific gravity of GFRP 1.9
2. In the bench test evaluation, endurance and wind-up rigidity are same as those of the steel leaf spring (existing), however, lateral rigidity is about 1/2 of that of the steel leaf spring (existing) as the modulus of bending of GFRP is low.
3. In the vehicle test evaluation (performance), stress frequency, stress at overinput and roll rigidity are same as those of the steel leaf spring (existing). Effect of the low lateral rigidity was expected to appear in the handling and stability, but no effect was found.

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Interlaboratory Tests on Microscopic Evaluation of Non-Metallic Inclusions in Steels for Spring Use

Committee on Evaluation of Non-Metallic Inclusions, S Nishijima, E. S ...

1987 Volume 1987 Issue 32 Pages 52-74
Published: March 31, 1987
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1987.52

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Adequate evaluation of non-metallic inclusions (nmi) is one of the key technologies for modern spring steels being guaranteed for high fatigue performance. In a preceding work by the Committee, six different microscopic testing methods of nmi have been compared through an interlaboratory testing program. The examined testing methods were that of Japanese Industrial Standard based on area proportion measurement, those of ASTM and DIN both using reference charts, and three others consisting of penalty point evaluation. As a conclution of the work, it was felt that one of the penalty point method named PP-1 could be accepted as a standard evaluation method of nmi, if testing practice was properly developed and the validity of the method well demonstrated.
In this work, interlaboratory comparison tests were carried out for microscopic evaluation of nmi using a tentative testing method based on PP-1, besides for evaluation of fatigue properties by rotating bending tests, on three shot-peened spring steel wires of Si-Cr type, all at a same strength but with different levels of nmi. The proposed nmi testing method was comprised of (1) counting the number of granular nmi existing within a specified testing area of the specimen section, separately according to their size, and (2) summing-up the penalty points for different size classes, each being obtained by multiplying the number of nmi for a class with respective penalty factor.
It was found that the fatigue fracture at high-cycle range was initiated from nmi at interior of the specimen and the results of fatigue tests could consistently be explained by the stress intensity factor at crack initiation locus. This lead to determine the penalty factors for different size classes in a rational way, and the evaluated penalty points of nmi for three materials could successfully predict the difference in fatigue performances between them. Thus it was confirmed that the proposed method was enough valid and practical for discriminating materials for spring use from fatigue point of view.

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Embrittlement of Coatings in Electrogalvanizing Process and Removal of Brittleness

Committee for removal of brittleness after surface

1987 Volume 1987 Issue 32 Pages 75-101
Published: March 31, 1987
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1987.75

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Although electroplating has been widely employed as a standard surface treatment for springs, some problems have still remained to be solved in relation to the embrittlement of electroplated coatings. For electrogalvanized coatings, Committee has made joint researches to understand the quantitative relationships between each electrogalvanizing step and embrittlement, to establish a system which can prevent embrittlement from occurring, and to evaluate embrittlement-prevention effect due to some baking conditions together with embrittlement by using actual springs.
The results are shown below.
(a) In the pretreatment step for electrogalvanizing, acid rinsing causes sever embrittlement, which can be effectively prevented by using inhibitors.
(b) Electrolytic degreasing rarely embrittles anodes and cathodes.
(c) The influence of the kinds of plating baths decreases in the descending order of chloride, zincate and cyanide baths.
(d) The system in which embrittlement occurs a little is as follows: Acid rinsing with a inhibitor added → anodic or cathodic electrolytic degreasing → zinc chloride bath.
(e) Wire springs to which wire drawing was applied undergo less embrittlement.
(f) As to heat treatment, oil quenching-tempering gives greater embrittlement than austempering.
(g) It is desirable for heat-treated products to be baked as enough as possible.
(h) With regard to the effects of flat spring hardnesses after heat treatment, the degree of embrittlement considerably decreases in the hardness-descending order of HRC52, HRC46 and HRC42.

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