Holoparasites have evolved a number of adaptations for pollination in parallel with their parasitic strategies. Complex floral pigmentation patterns, comprising spots or stripes that act as visual nectar or landing guides for pollinators, are common and diversified, but their structure and function are poorly understood and almost nothing is known about the role that micromorphological features might play in generating or complementing those visual stimuli. By means of scanning electron and confocal digital microscopy, petal micromorphology was analysed in the two subspecies of the holoparasitic Cistanche phelypæa (subsp. phelypæa and subsp. lutea, Orobanchaceae). Plant material was collected in the semi-deserts of southeastern Spain in 2009 (subsp. lutea), and in coastal salt marshes in southern Portugal in 2012 (subsp. phelypæa). Cistanche phelypæa subspecies were already known to differ in several morphological features of flowers and leaves, as well as in their habitats and hosts. Our data have shown that they also differ in several micromorphological features of the petal epidermis. Three different sculpture types of the petal epidermis were recognized. Our results show that petal micromorphology can be used in the separation of taxa, with potential utility in the determination of dried specimens in this genus, inherently poorly preserved in herbaria. The putative influence of the visual and tactile effects originating from this micromorphological variability on the interactions between plants and pollinators and in the reproductive biology of the former is discussed in detail.

Tensile uniaxial test is typically used to determine the strength and plasticity of a material. Nominal (engineering) stress-strain relationship is suitable for determining properties when elastic strain dominates (e.g., yield strength, Young’s modulus). For loading conditions where plastic deformation is significant (in front of a crack tip or in a neck), the use of true stress and strain values and the relationship between them are required. Under these conditions, the dependence between the true values of stresses and strains should be treated as a characteristic—a constitutive relationship of the material. This article presents several methodologies to develop a constitutive relationship for S355 steel from tensile test data. The constitutive relationship developed was incorporated into a finite element analysis of the tension test and verified with the measured tensile test data. The method of the constitutive relationship defining takes into account the impact of high plastic strain, the triaxiality stress factor, Lode coefficient, and material weakness due to the formation of microvoids, which leads to obtained correctly results by FEM (finite elements method) calculation. The different variants of constitutive relationships were applied to the FEM loading simulation of the three-point bending SENB (single edge notched bend) specimen to evaluate their applicability to the calculation of mechanical fields in the presence of a crack.

This paper presents the research results on the mechanical behavior of the low-carbon rolled steel of a sea portal crane after a 33-year operation depending on the operational stresses and rolling direction in order to assess its serviceability. The tensile properties of steels were investigated using rectangular cross-section specimens with different thicknesses and the same width. Strength indicators were slightly dependent on the considered factors (operational conditions, the cutting direction, and thickness of specimens). However, a clear trend of higher ultimate strength for thinner specimens was noticed, especially in the case of more brittle material due to its operational degradation. Plasticity of the tested steel specimens was more sensitive to the influence of the above-mentioned factors than strength but less sensitive than impact toughness. Uniform elongation was slightly less for thinner specimens regardless of the investigated steel state or the orientation of specimens relative to the rolling direction. The post-necking elongation was lower for transversal specimens compared with longitudinal ones, and the effect was more significant when testing steel with the lowest brittle fracture resistance. Among the tensile properties, non-uniform elongation was demonstrated to be the most effective for assessing the operational changes in the state of rolled steels.

In the paper are presented test results of fracture process in brittle-to-ductile transition range for two microstructural types of S355JR steel – ferrite-pearlite and ferrite-carbides. For both kinds of S355JR steel obtained in temperature range of transition region the strength and plastic properties are similar, but the fracture toughness characteristics showed significantly are various. To clarify the differences in the course of trends in the mechanical characteristics performed metallographic and fractographic observations using the scanning electronic microscope. The fractographic examination showed that changes in the fracture surface morphology were dependent on the test temperature. It was also found that during the subcritical crack growth the region of ductile fracture extension reduced with decreasing temperature. The results of finite element method (FEM) calculation the stress fields in front of the crack of single edge notch in bending (SENB) specimens in the range of brittle-to-ductile transition are presented also. The FEM calculations were performed on the numerical model of SENB specimen using the ABAQUS program.

Laser welded joint of ferritic low carbon steel DC05 was manufactured as Tailored Blank and examined by non-destructive visual testing and destructive testing by macro- and microscopic examination and hardness measurements. The tensile strength of the welded joint was 280 MPa and corresponds to the tensile strength of the base material. Microscopic observations of thinner plate revealed heat affected zone with coarse grain, in contrast to the thicker plate where coarse grain was not observed. Detailed analysis of laser remelted area on plates after various cold deformation (1%, 4.15% and 12.5%) reveals a significant influence of the plate state on the occurrence of grain growth. The increase in the width of the coarse-grained zone after 12.5% deformation increases by approximately 60% compared to the undeformed state, regardless of the travel speed.