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To obtain better fatigue resistance for marine engineering equipment welded joints in the design stage, the design method of the marine engineering equipment welded joint design stage needs to be studied.

Based on the structural stress theory, a design method of the marine engineering equipment welded joints with better fatigue performance is proposed. The effectiveness of the method is demonstrated through the simulation analysis and fatigue test of typical marine engineering equipment welded joints.

Methods based on the theoretical advantages of structural stress and the principle of ensuring that the welded joint has a low degree of stress concentration.

The design method of marine engineering equipment welded joints proposed in this study provides a set of operable design routes for technicians, which can better meet the needs of engineering applications.

In order to obtain the relationship between the geometry and stress concentration of load-bearing welded joints, the fatigue design method of welded structures based on stiffness coordination strategy is studied.

Based on the structural stress theory, a new method for anti-fatigue design of welded structures oriented to stiffness coordination strategy is proposed, and the detailed implementation process of this method is given. This method is also called the three-stage anti-fatigue design method for welded structures, which includes three stages, namely, identification, analysis and relief of stress concentration.

Through the experimental analysis of welded joints in IIW standard, the effectiveness of stiffness coordination in welded joint design is proved. The method is applied to the design of welded parts and products, and the feasibility of the method in alleviating the phenomenon of stress concentration and improving the fatigue resistance of welded structures is verified.

In this study, based on the principle of coordinated design of weld stiffness, a three-stage anti-fatigue design method of welded structure is proposed. The method has practical value for the optimization design and anti-fatigue performance improvement of welded structure in engineering products.

The purpose of this paper is to optimize the key dimensions parameters of the missile suspension structure to ensure the structural fatigue life (>10000 cycles) with the reliability of 0.995.

The design objective is the fatigue life reliability of the structure, while the design variables are the four fatigue‐sensitive dimensions. The nominal stress approach is introduced to predict the fatigue life, and it was verified by comparing with experimental data. The second respond surface method is applied to solve the reliability in a finite element‐supported analysis using software MSC Patran/Nastran. A Sequential quadratic programming (SQP) algorithm is used for structure optimization.

The fillet radius r is the most important factor that influences the fatigue life reliability of the structure. The four optimal dimensions parameters are obtained by a reliability‐based design optimization process with the fatigue life and reliability fulfilling the demands.

The optimal result can be used as the design values for missile suspension structure. The feasibility of the reliability‐based design optimization method is validated for the design of missile suspension structure.

THE increasingly competitive nature of both the operational and manufacturing sides of the aviation business has had the effect of making the designer more conscious of the economic characteristics which he is building into his aircraft, and these have now become a major design consideration.

This paper aims to present an engineering computational method for fatigue life evaluation of welded structures on large-scale equipment under random vibration load.

Based on a case study of the traction transformers, virtual fatigue test (VFT) was proposed via numerical simulation approach. Static analysis was conducted to identify the risky zone and then dynamic response of the risky welds under random vibration load was calculated based on frequency-domain structural stress method (FDSSM) theory, life distribution and associated survivability at various locations of the structure were obtained. Structural modification was finally performed according to the evaluation results. Moreover, experimental test was carried out and compared with the virtual test result.

By applying the virtual test, fatigue life of the complex welded structures on large-scale equipment can be accurately and efficiently obtained considering dynamic effect under random vibration load. Meanwhile, risky welds can be directly determined and targeted modification scheme can be accordingly concluded. Validity of the VFT result was proved by comparing with the experimental test.

The proposed method can help obtain equivalent structural stress and fatigue life distribution of the welded structure at any position with various survivability and make quantitative evaluation on the life-extending effect of the structural modification. This method shows significant cost and efficiency advantages over experimental test during design stage of the large-scale structures in numerous manufacturing industries.

SEVENTEEN papers were presented during the three days of the conference on a variety of topics affecting fatigue in aircraft structures. The conference was organized under the joint auspices of the Department of Civil Engineering and Engineering Mechanics, Columbia University, and the Air Research and Development Centre, U.S.A.F., Baltimore.

IN the year 1945 aircraft structural design had reached an advanced stage in this country, as judged by all previous standards. The needs of war and the vast expenditure on aircraft design and manufacture had unquestionably forced the pace of progress. On the other hand, war‐time conditions must inevitably have tended to produce an unbalanced growth. Expenditure of money and effort was accompanied by a no less drastic expenditure of technical capital, and really long‐term thinking was unavoidably put aside.

In this paper an overview of the issues underlying surface mount solder joint long‐term reliability is presented. The paper gives state‐of‐the‐art solutions for ‘Design for Reliability’ in simple design tool form, discusses the important accelerated reliability test issues, and provides the equations to estimate the reliability of SM product in use as well as the expected cyclic life in accelerated tests.

This paper reviews some continuing IBM study efforts conducted on surface mounted Leadless Chip Carrier (LCC) packaging for use in high density, high thermal stress military environments. The paper presents some designs, materials and solder joint processing considerations that can affect solder joint fatigue life. Also discussed are some thermal cycling test limitations, important properties of solder failure mechanisms and finally some technical concerns with both WS 6536E and DoD 2000 specifications as to their limitations with future surface mounted technologies.

Contrary to the general conception of adding weight for fatigue resistance it is sometimes possible to reduce the fatigue hazard by removing weight. The theory of having bearing area, tear‐out area, and tension area sufficient to develop the full shear strength of a rivet is not necessarily sound when fatigue life is considered. Accordingly, marked improvements in fatigue resistance can be achieved by reducing the underlying areas to such an extent that they are incapable of inducing loads causing fatigue failures of the main structure. Results of tests involving fatigue failure are given, and seven basic considerations in the design of fatigue resistant structures are listed.