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The purpose of this paper is to investigate the ballistic impact response of square clamped fiber-metal laminates and monolithic plates consisting of different metal alloys using the ANSYS LS-DYNA explicit nonlinear analysis software. The panels are subjected to central normal high velocity ballistic impact by a cylindrical projectile.

Using validated finite element models, the influence of the constituent metal alloy on the ballistic resistance of the fiber-metal laminates and the monolithic plates is studied. Six steel alloys are examined, namely, 304 stainless steel, 1010, 1080, 4340, A36 steel and DP 590 dual phase steel. A comparison with the response of GLAss REinforced plates is also implemented.

It is found that the ballistic limits of the panels can be substantially affected by the constituent alloy. The stainless steel based panels offer the highest ballistic resistance followed by the A36 steel based panels which in turn have higher ballistic resistance than the 2024-T3 aluminum based panels. The A36 steel based panels have higher ballistic limit than the 1010 steel based panels which in turn have higher ballistic limit than the 1080 steel based panels. The behavior of characteristic impact variables such as the impact load, the absorbed impact energy and the projectile’s displacement during the ballistic impact phenomenon is analyzed.

The ballistic resistance of the aforementioned steel fiber-metal laminates has not been studied previously. This study contributes to the scientific knowledge concerning the impact response of steel-based fiber-metal laminates and to the construction of impact resistant structures.

The purpose of this paper is to investigate the fatigue and failure of commercial vehicle serial stress-peened leaf springs, emphasizing the technological impact of the material, the thermal treatment and the stress-peening process on the microstructure, the mechanical properties and the fatigue life. Theoretical fatigue analysis determines the influence of each individual technological parameter. Design engineers can assess the effectiveness of each manufacturing process step qualitatively and quantitatively, and derive conclusions regarding its improvement in terms of mechanical properties and fatigue life.

Two different batches of 51CrV4 were examined to account for potential batch influences. Both specimen batches were subjected to the same heat treatment and stress-peening process. Investigations of their microstructure, hardness and residual stress state on the surface’ areas show the effect of the manufacturing process on the mechanical properties. Wöhler curves have been experimentally determined for the design of high-performance leaf springs. Theoretical fatigue analyses reveal the influence of every above mentioned technological factor on the fatigue life of the specimens. Therewith, the effectiveness and potential for further improvement of the manufacturing process steps are assessed.

Microstructural analysis and hardness measurements quantify the decarburization and the degradation of the specimens’ surface properties. The stress-peening process causes significant compressive residual stresses which improve the fatigue life. On the other hand, it also leads to pronounced surface roughness, which reduces the fatigue life. The theoretical fatigue life analysis assesses the mutual effect of these two parameters. Both parameters cancel each other out in regards to the final effect on fatigue life. The sensitivity of the material and the potential for further improvement of both heat treatment and stress peening is appointed.

All quantitative values given here are strictly valid for the present leaf spring batches and should not be widely applied. The results of the present study indicate the sensitivity of high-strength spring steel used here to the various technological factors resulting from the heat treatment and the stress-peening process. In addition, it can be concluded that further research is necessary to improve the two processes (heat treatment process and the stress peening) under serial production conditions.

The microstructure investigations in conjunction with the hardness measurements reveal the significant decrease of the mechanical properties of the highly stressed (failure-critical) tensile surface. Therewith, the potential for improvement of the heat treatment process, e.g. in more neutral and controlled atmosphere, can be derived. In addition, significant potential for improvement of the serially applied stress-peening process is revealed.

The paper shows a systematic procedure to assess every individual manufacturing factor affecting the microstructure, the surface properties and finally, the fatigue life of leaf springs. An essential result is the quantification of the surface decarburization and its influence on the mechanical properties. The methodology proposed and applied within the theoretical fatigue life analysis to quantify the effect of technological factors on the fatigue life of leaf springs can be extended to any engineering component made of high-strength steel.

The purpose of this paper is to develop a FE based modeling procedure for describing the mechanical behavior of high‐performance leaf springs made of high‐strength steels under damaging driving manoeuvres.

The type and number of finite elements over the thickness of leaves, as well as the definition of contact, friction and clamping conditions, have been investigated to describe the mechanical behavior in an accurate and time‐effective manner. The proposed modeling procedure is applied on a multi‐leaf spring providing complex geometry and kinematics during operation. The calculation accuracy is verified based on experimental stress results.

A FE based modeling procedure is developed to describe the kinematics and mechanical behavior of high‐performance leaf springs subjected till up to extreme driving loads. Comparison of numerically determined stress distributions with corresponding experimental results for a serial front axle multi‐leaf spring providing complex geometry and subjected to vertical and braking loads confirms high calculation accuracy.

The proposed FE based model is restricted to linear elastic material behavior, which is, however, reasonable for the high‐strength steels used for leaf spring applications.

The proposed FE procedure can be applied for the design and optimization of automotive leaf springs, especially for trucks.

The proposed procedure is simple and can be applied in a very early design stage. It is able to describe accurately the leaf behavior, especially the stiffness and stress response under the most significant driving events. It goes far beyond today's practice for leaf spring design, which is based on analytical methods not covering complex axle and steering kinematics, large deformations and non‐linearities.

The paper aims to illustrate the application of a state-of-the-art fatigue prediction concept (IIW recommendations) to the ADR calculation requirements, in order to include failure-critical weld details to the strength assessment of road tanks. The level of calculation accuracy and, therefore, safety of such structures transporting dangerous goods can be substantially increased.

A case study of a 2-compartment aluminum alloy LBGF tank used for the transportation of gasoline/petroleum products is conducted adopting the meshing directives of the structural hot spot stress concept (SHSSC) of the IIW recommendations for the weld details of the structure. The stresses on the prescribed Hot Spots are extracted from the solutions of each load case described in the ADR legislation and assessed both in terms of static strength according to EN 14286 and fatigue strength using the standardized IIW assessment curves (FAT curves).

The detailed analysis of the road tank has successfully allocated the failure critical points of the structure. Additionally it has illustrated the ability of the embedded fatigue concept to accurately calculate the stresses which can later be used for the durability evaluation, providing that at least some operational load spectra become available.

The use of a global meshing and calculation concept offers a relatively limited accuracy level considering any individual weld detail. On the other hand, it offers a sufficient overview of the whole structure with minimum effort and costs.

Time-consuming integrity inspections of road tanks can be minimized, as the failure critical locations are identified and therefore easily monitored. Furthermore, the transformation of the fatigue life prediction issued by the proposed calculation into actual operational time may be used to determine realistic time intervals between service pauses required for the safe operation of such structures.

The present study constitutes the first approach of embedding the SHSSC into the calculation of large-scale structures such as road tanks and verifies the applicability of this concept beyond simple geometries and load cases.