The ecological meanings clearly indicates the need of reducing of the concentration of the CO2in the atmosphere, which can be accomplished through the lowering of the fuel consumption. This fact implies the research for the new construction solutions regarding the reduction of the weight of vehicles. The reduced weight of the vehicle is also important in the case of application of the alternative propulsion, to extend the lifetime of the batteries with the reduction of recharge cycles. The use of cast alloy AlZnMgCu compliant of plastic forming class 7xxx alloy, are intended to significantly reduce the weight of the structures, while ensuring high strength properties. The wide range of the solidification temperature, which is more than 150°C, characterizes this alloy with a high tendency to create the micro and macro porosity. The study presents the relationship between the cooling rate and the area of occurrence and percentage of microporosity. Then the results were linked to the local tensile strength predicted in the simulation analysis. The evaluation of the microporosity was performed on the basis of the CT (computed tomography) and the analysis of the alloy microstructure. The microstructure analysis was carried out on test specimen obtained from the varying wall thickness of the experimental casting. The evaluation of the mechanical properties was prepared on the basis of the static tensile test and the modified low cycle fatigue test (MLCF).

The article discusses the weldment to casting conversion process of rocker arm designed for operation in a special purpose vehicle to

obtain a consistency of objective functions, which assume the reduced weight of component, the reduced maximum effort of material

under the impact of service loads achieved through topology modification for optimum strength distribution in the sensitive areas, and the

development of rocker arm manufacturing technology. As a result of conducted studies, the unit weight of the item was reduced by 25%,

and the stress limit values were reduced to a level guaranteeing safe application.

The article presents the analysis of properties of the high-strength AlZnMgCu (abbr AlZn) aluminium alloy and estimates possibilities of

its application for responsible structures with reduced weight as an alternative to iron alloy castings. The aim of the conducted studies was

to develop and select the best heat treatment regime for a 7xx casting alloy based on high-strength materials for plastic working from the

7xxx series. For analysis, wrought AlZnMgCu alloy (7075) was selected. Its potential of the estimated as-cast mechanical properties

indicates a broad spectrum of possible applications for automotive parts and in the armaments industry. The resulting tensile and fatigue

properties support the thesis adopted, while the design works further confirm these assumptions.

The development of a novel design for the toothed segment of drive transmission in longwall shearer is expected to significantly reduce

the cost of individual components of the feed system and the related work of repair and renovations, increasing at the same time the safety

of mine repair teams.

The conducted experimental and numerical analysis of the state of stress and strain in the innovative design of the toothed segment has

enabled estimating the maximum effort of the developed structure. Based on the results of fundamental mechanical studies of the cast

L20HGSNM steel and fatigue tests combined with the numerical stress/strain analysis, the fatigue life curve was plotted for the examined

casting of the rack.