Wyniki wyszukiwania - BazTech

1

Experimental investigation of concrete beams under bending, manufactured with 3D additive printing technology

Korol Ewelina, Jenta Arkadiusz, Chaudhari Ojas Arun, Wójcik Michał

Materiały Budowlane

|

2025

|

nr 11

1--8

EN

The article presents results of experimental research performed on concrete beams under bending, manufactured using additive 3D printing method. The aim of the research was to determine the nominal flexural strength affected by varying: layer orientation, geometry of a single layer and beam size. The results showed that the strength of beams with layers perpendicular to the load direction is several times higher than those with parallel layers, and significantly lower when the beam dimensions increase.

PL

Artykuł przedstawia wyniki badań doświadczalnych przeprowadzonych na belkach betonowych, wytworzonych przyrostową metodą druku 3D. Celem badań było określenie wytrzymałości nominalnej na zginanie, będącej pod wpływem zmiennych: układu warstw; geometrii pojedynczej warstwy oraz wielkości belki. Wyniki badań wykazały, że nośność belek z warstwami prostopadłymi do kierunku obciążenia jest wielokrotnie większa niż z warstwami równoległymi oraz znacznie mniejsza, gdy wymiary belki wzrastają.

2

Experimental study on dynamic compressive dimension effect and damage evolution law of fly ash concrete under seismic strain rate

Lian Yaojie, Liu Run, Jiang Haoyuan, Lian Huiheng, Yu Zhenpeng, He Yinpeng

Archives of Civil and Mechanical Engineering

|

2025

|

Vol. 25, no. 2

art. no. e64, 2025

EN

Many scholars have obtained preliminary findings regarding the study of the dynamic size effect of concrete; however, a unified explanation for the development law of internal damage in fly ash concrete caused by this dynamic size effect has not yet been achieved. Compression tests were conducted on cylindrical specimens of fly ash concrete with varying sizes under dynamic loads ranging from 1.0 × 10–5(s−1) to 1.0 × 10–2(s−1) seismic strain rate. The experimental findings indicate that the peak stresses were increased by 29.07%, 38.19% and 48.18% for the three sizes of specimens, large, medium and small, respectively, under the condition that the strain rate was increased from 1.0 × 10–5 (s−1) to 1.0 × 10–2 (s−1). From the overall trend analysis, the impact of strain rate on fly ash concrete gradually increases as the size decreases. The size effect of fly ash concrete can be attributed to the internal heterogeneity of specimens, which results in varying degrees of damage development. Similarly, the strain rate effect of meso-components is also caused by uneven damage development within fly ash concrete. The damage development law of fly ash concrete is then investigated by analyzing the changes in the 3D-DIC strain cloud map, using advanced technology known as 3D digital image correlation (3D-DIC). At strain rates of 1.0 × 10–4(s−1), 1.0 × 10–3(s−1), and 1.0 × 10–2(s−1), the full-stage damage degree factor (Df1) in the pre-loading phase is 76.47%, 54.90%, and 25.49% of the static strain rate (1.0 × 10–5(s−1)), respectively. At strain rates of 1.0 × 10–5(s−1) and 1.0 × 10–2(s−1), the slopes of post-peak damage change (Df2) for specimen sizes L, M, and S are 2.09, 2.27, and 2.5, and 2.25, 7.6, and 10.62, respectively. This suggests that in smaller specimens, damage development is primarily concentrated in the post-peak phase. Finally, the uniform static and dynamic size effect law of compressive strength in fly ash concrete is established based on the influence mechanism of damage development on dynamic strength and size effect. The research findings provide a theoretical foundation for the application and advancement of fly ash concrete engineering.

3

Ability of localizing gradient damage to determine size effect in concrete beams

Wosatko Adam, Pamin Jerzy, Winnicki Andrzej

Journal of Theoretical and Applied Mechanics

|

2024

|

Vol. 62 nr 2

193--206

EN

The objective of the paper is to demonstrate the potential of the localizing gradient dam- age model in size effect simulations. Three different gradient activity functions for variable internal length scale are considered. Numerical simulations for an unnotched beam under three-point bending are referred to the experiment performed by Gr´egoire et al. (2013). A confrontation with the conventional gradient damage model as well as mesh sensitivity studies are also presented. It is proved that the localizing gradient damage model with differ- ent variants of the gradient activity function can reproduce the size effect quite reasonably.

4

Mesoscale modeling of size effect of BFRP‑reinforced concrete columns under pure torsion

Jin Liu, Zhu Huajie, Lei Yushuang, Du Xiuli

Archives of Civil and Mechanical Engineering

|

2024

|

Vol. 24, no. 1

art. no. e30, 2024

EN

There have been few studies regarding the torsional behavior of FRP-reinforced concrete members. Only the CSA S806-12 and the ACI 440.11-22 codes specify the design criteria for their pure torsional capacities. A meso-scale numerical model of circular/square concrete columns with BFRP bars was developed, in which concrete heterogeneity can be explicitly described. This study evaluated longitudinal reinforcement ratios, stirrup ratios, cross-section shape, and structural size for their effects on BFRP-reinforced concrete column torsional performance. For BFRP-reinforced concrete columns, the nominal torsional strength exhibits a significant size effect, while the longitudinal reinforcement and stirrups ratio cannot suppress the size effect. Furthermore, a modified size effect law was developed to quantitatively reflect the relationship between nominal torsional strength and structural size. BFRP-reinforced concrete columns present a more substantial size effect than steel-reinforced ones. Finally, a modified calculation formula of pure torsional capacity was proposed considering the effect of structural size.

5

Dynamic compressive behavior of impact‑damaged and water‑soaked sandstone with different length‑to‑diameter ratios

Luo Kun, Wang Yuanmin, Luo Song, Li Xiaoshuang, Peng Kang

Archives of Civil and Mechanical Engineering

|

2024

|

Vol. 24, no. 1

art. no. e21, 2024

EN

In backfill mining, surrounding rock damaged by impact loading (e.g. blasting) is immersed in backfill water after backfilling, and the instability of the impact-damaged and water-soaked (IDWS) surrounding rock can occur under blasting loads. To study the dynamic mechanical properties and the size effect of rock under such working conditions, triaxial dynamic compression tests were conducted on four groups (four length-to-diameter ratios) of first impact-damaged and then water-soaked sandstone specimens using an improved split Hopkinson pressure bar device. The test results show that, at a similar strain rate (approximately 10 s −1 ), the peak strength and elastic modulus of IDWS specimens are lower than those of the intact specimens, whereas the peak strain is higher than that of the intact specimens. Both the peak strength and peak strain of the IDWS specimens increase with strain rate, exhibiting a strong strain rate dependency. The peak strength, peak strain, and elastic modulus all display a size effect. This size effect varies over different strain rate ranges. When the strain rate is approximately 10 s −1 , the peak strength decreases as the length-to-diameter ratio increases. In contrast, at a strain rate of approximately 30 s −1 , the peak strength increases with an increase in the length-to-diameter ratio. There is a linear relationship between the incident energy and absorbed energy of the intact and IDWS specimens. Under the same incident energy, the IDWS specimens show higher absorbed energy than the intact specimens. This relationship is independent of the length-to-diameter ratio of rock specimens.

6

Size effect and anisotropy of rock fractures: insights from investigations on a large-scale fracture surface

Yang Jinjin, Wang Zhechao, Wang Ende, Qiao Liping, Fu Jianfei, Li Wei, Li Jiajia

Acta Geophysica

|

2024

|

Vol. 72, no. 4

2487--2501

EN

The mechanical and hydraulic behaviors of rock fractures are strongly dependent on the properties of the surface morphology. In this study, a sandstone fracture surface is taken as the research object. The morphological properties of the fracture surface characterized by parameters Z2s, Z2, and SRv are analyzed under the different sampling windows and profile lines. The results show that the large sampling window is more conducive to obtaining stable values of the morphology parameter Z2s. The coefficient of variation (CV) and the percentage of variation (PV) are proposed to determine the stable values of the morphology parameter Z2s, which is defined as a representative elementary surface (RES). It is confirmed that there is a RES with a size of 220 mm in the study region. The large sampling window generates a long correlation length of the morphology parameter Z2s. The differential sensitivities of the morphology parameters Z2 and SRv are compared under the different profile lines. It is found that the parameter Z2 can better describe the random variation properties of the surface morphology, while the parameter SRv is more suitable for describing the spatial structural variation properties of the surface morphology. The findings of this work are of great significance for investigating the size effect and anisotropy of rock fracture permeability.

7

Size‑dependent constitutive model incorporating grain refinement and martensitic transformation

Liu Shengqiang, Li Wei, Shen Jinxia, Yang Xiaoming, Wang Baoyu, Liu Jinping

Archives of Civil and Mechanical Engineering

|

2023

|

Vol. 23, no. 1

art. no. e38, 2023

EN

The deformation behaviour of materials at the micro-scale level is different from that at the macro-scale level due to the effect of grain size (GS). The mechanism of the influence on martensitic transformation by GS is still unclear, and there are relatively few studies on the relationship between grain refinement and martensitic transformation, most of which focus on the relationship between the initial GS of the material and martensitic transformation. Therefore, in this study, the interaction between grain refinement and martensitic transformation was investigated using a dislocation density-based multiscale constitutive model that incorporated dislocation sliding, strain-induced martensitic transformation (SIMT) related to grain size, and grain refinement. The proposed model evaluated the GS-dependent deformation behaviour of 316L stainless steel (SS). Subsequently, a genetic algorithm was used to determine the parameters of the established model, and the calculated results were compared with that of the experimental data to verify the accuracy of the model. The developed multiscale constitutive model was implemented in Abaqus user subroutine to further investigate the deformation mechanism and validate its accuracy. The results demonstrated that the GS had a significant effect on the SIMT, with the volume fraction of martensite increasing with a rise in the initial austenite GS. In addition, grain refinement affected SIMT and the growth rate of martensite content decreased with the grain refinement caused by deformation. The formation of martensite led to grain refinement, with the refined grains producing negative feedback on the SIMT, thus inhibiting the occurrence of martensitic transformation. This study revealed the microscopic deformation mechanism of 316L SS and provided a constitutive model for micro-forming.

8

Nonlinear forced vibration analysis of micro-rotating shaft-disk systems through a formulation based on the nonlocal strain gradient theory

Panahi Ramin, Asghari Mohsen, Borjalilou Vahid

Archives of Civil and Mechanical Engineering

|

2023

|

Vol. 23, no. 2

art. no. e85, 2023

EN

The paper presents an upgraded size-dependent formulation for micro-rotating shaft-disks system to study their nonlinear forced vibration behavior. The novel formulation is based on the nonlocal strain gradient theory (NSGT). To achieve this goal, first of all, by incorporating the geometrical nonlinearity within the Rayleigh beam theory, the governing equations of the lateral motion of the system are derived by the Hamilton principle and then converted into a complex form. By defning some dimensionless parameters, the normalized form of the complex governing equation is also extracted. In the next step, the Galerkin method is implemented to establish an infinite set of ordinary differential equations (ODEs). Then, with the help of the method of multiple scales, the nonlinear ODE is solved to attain the vibrational amplitude of the system as well as its forward and backward natural frequencies. Lastly, an all-out parametric study is conducted to appraise the impact of some important factors like the nonlocal theory parameter, the strain gradient length scale parameter, the rotational speed, the amount of mass eccentricity and the internal damping coeffcient on the motion amplitude and natural frequencies. The numerical outcomes illuminate well that depending on the relative value of two non-classical parameters of NSGT, this theory have the potential to reflect the hardening or softening attribute of small-scaled mechanical elements.

9

Measurement and analysis of pocket milling features in abrasive water jet machining of Ti-6Al-4V alloy

Natarajan Yuvaraj, Raj K. L. Naresh, Tandon Puneet

Archives of Civil and Mechanical Engineering

|

2023

|

Vol. 23, no. 1

art. no. e42, 2023

EN

The present work deals with the size effect of abrasive water jet milling parameters on the square pockets of Ti-6Al-4V alloy. In this study, the abrasive mesh size, water jet pressure and traverse rate were chosen as milling variables and their effect on pocket features such as depth of cut, undercut, material removal rate, and surface roughness were examined. This study also characterizes the milled pocket surfaces under different milling conditions. Most of the measurements and surface characterizations were done using the Dino-Lite Digital Microscope. For both #80 and #100 abrasives, the AWJ-milled pockets were formed with variations in depth milled and rugged surface by increasing the water jet pressure from 175 to 200 MPa under all the selected traverse rate conditions. Also, the variations of depth of cut in successive trajectories found to have a speed bump effect. At these settings, distribution of energy to the work material was more due to deceleration of jet in the boundary close by and changes made in the feed directions in raster path from 0° to 90° at a step-over distance of 0.2 mm. This yielded undercuts in the milled pocket corners. However, there was a significant reduction in the undercut with a water jet pressure of 125 MPa and a traverse rate of 3500 mm/min were employed. Besides, the abrasive mesh size #100 had a better surface topography, and also strong jet footprints were observed with mesh size of #80. Based on the experiments results, the size effect of different milling parameters was seen having influence on the pocket geometry and surface features.

10

Influence of shear depth on seismic performance of shear wall reinforced with BFRP bars: mesoscale modelings

Jin Liu, Miao Liyue, Du Xiuli

Archives of Civil and Mechanical Engineering

|

2023

|

Vol. 23, no. 1

art. no. e4, 2023

EN

The seismic performances of 28 geometrically similar concrete shear walls reinforced with basalt fiber-reinforced polymer (BFRP) bars were simulated using a mesoscale modeling approach. In the modeling, concrete heterogeneities were explicitly described, and the interaction between BFRP bars and surrounding concretes was also considered. The influences of shear depth, shear span ratio and vertical reinforcement ratio on the failure of shear walls were investigated. The simulation results indicated that with the increase of shear depth, the failure modes were basically the similar, while the nominal shear strength decreased significantly, namely, the presence of size effect was demonstrated. The shear wall would exhibit different failure modes as the shear span ratio varies. Moreover, it was found that the vertical BFRP bar presented an ignorable influence on the failure mode, while the increase of vertical reinforcement ratio would obviously improve the shear strength of BFRP-RC shear wall. Finally, the present simulated shear strengths were compared with some available size effect laws and some codes.

11

Size effect of synthetic fibre reinforced concrete - investigation using a semi-discrete analytical beam model

Tóth Mária Erdélyiné, Pluzsik Anikó

Architecture Civil Engineering Environment

|

2023

|

Vol. 16, no. 3

117--129

EN

The size effect is a well-known characteristic of concrete structures. However, in the case of fibre-reinforced concrete (FRC), this issue is not thoroughly explored. Most design recommendations of FRC neglect the size effect or handle the behaviour of FRC structures in case of different structural sizes similar to plain concrete structures (assuming FRC is a homogeneous material). The aim of this paper is to show that the size effect of FRC can be divided, the share of the concrete matrix and the fibres in the size-dependent properties is separable. For the size effect research fifteen synthetic macro fibre reinforced concrete and six plain concrete beam specimens were prepared and tested in three different sizes and then evaluated with the semi-discrete analytical (SDA) model. The analysis of the experimental specimens has shown that the size effect significantly influences the concrete material in the case of FRC with softening material behaviour, but the residual loadbearing capacity which mainly arise from the local bridging effect of fibres is essentially independent of the structural size. It is also shown in this paper that the two defining parameters of the SDA model is independent of the structural size, so the model provides an excellent tool in case of the design of real-sized FRC structures.

12

Meso-scale modelling of size effect on pure torsional-shear of RC columns

Jin Liu, Zhu Huajie, Du Xiuli

Archives of Civil and Mechanical Engineering

|

2022

|

Vol. 22, no. 1

art. no. e36, 2022

EN

Under the action of earthquake, the reinforced concrete (RC) columns may subject to torsional moment, and the existence of torsion will change the failure mode of RC columns. Moreover, the torsional fracture of RC columns often presents a brittle fracture pattern, and thus may have an obvious size effect. In this work, a three-dimensional meso-scale simulation approach was utilized to study the torsional failure of RC columns. The influence of structural size, longitudinal reinforcement ratio, stirrup ratio and cross-sectional shape on torsional failure of RC columns was investigated. The results show that: (1) the tested RC columns show brittle failure patterns, the nominal torsional strength presents obvious size effect; (2) the longitudinal reinforcement presents little influence on the size effect; (3) columns with square cross-section present stronger size effect than the ones with circular shape; (4) stirrups can improve the torsional strength, while they would weaken the size effect on torsional strength. In addition, a novel size effect law that can describe the quantitative influence of stirrup ratio was established. Finally, based on the variable angle truss model, the formulas for calculating the pure torsional capacity of RC columns were modified, considering the quantitative influence of the stirrup ratio on the size effect.

13

Analytical and parametric analysis of thermoelastic damping in circular cylindrical nanoshells by capturing small-scale effect on both structure and heat conduction

Li Ming, Cai Youjie, Bao Li, Fan Rui, Zhang Hongbin, Wang Hongyan, Borjalilou Vahid

Archives of Civil and Mechanical Engineering

|

2022

|

Vol. 22, no. 1

art. no. e14, 2022

EN

This article intends to examine thermoelastic damping (TED) in circular cylindrical nanoshells by considering small-scale effect on both structural and thermal areas. To fulfill this aim, governing equations are extracted with the aid of nonlocal elasticity theory and dual-phase-lag (DPL) heat conduction model. Circular cylindrical shell is also modeled on the basis of Donnell–Mushtari–Vlasov (DMV) equations for thin shells. By inserting asymmetric simple harmonic oscillations of nanoshell into motion, compatibility and heat conduction equations, the size-dependent thermoelastic frequency equation is obtained. By solving this equation and deriving the frequency of nanoshell affected by thermoelastic coupling, the value of TED can be calculated through complex frequency approach. Results of this investigation are given in two sections. First, to appraise the validity of presented formulation, a comparison study is conducted between the results of this work in special cases and those reported in the literature. Next, by providing several numerical data, a detailed parametric study is performed to highlight the profound impact of nonlocality and dual-phase-lagging on TED value in simply supported cylindrical nanoshells. The influence of some determining factors such as mode number and type of material on TED is also evaluated.

14

Size effect at testing strength properties of concrete

Akram Amanda

Budownictwo i Architektura

|

2021

|

Vol. 20, no 4

37--45

EN

Various strength characteristics of concrete are considered as fracture parameters. The compressive strength of concrete is of paramount importance when designing concrete structures, whereas tensile strength of concrete is the basic property when estimating cracking resistance of a structure and analysing fracture processes in concrete. When testing the compressive strength of concrete, the results are dependent on the shape and dimensions of used specimens. Some findings reported in the literature suggest that size effect exists also when testing such fracture properties of concrete as tensile strength. Unfortunately this problem is much less recognized and described compared to size effect in compressive test results. In this paper, the experimental investigation is presented on how the length of cylindrical specimens influences the tensile splitting strength of concrete obtained by means of the Brazilian method. Additional variable parameters were: type of aggregate (natural gravel and crushed granite) and cement-water ratio (C/W = 1.8 and C/W = 2.6). In conducted laboratory experiments a higher splitting tensile strength of concrete was noted for all specimens with nominal dimensions of 150×150 mm, compared to specimens 150×300 mm in size, regardless of type of aggregate or cement-water ratio.

15

Modeling of dynamic growth of a micro-scaled void based on strain gradient elasto-plasticity

Ma Xinbing, Liu Jinxing, Wang Jiadong, Pan Hao

Journal of Theoretical and Applied Mechanics

|

2020

|

Vol. 58 nr 4

927--941

EN

Void initiation and growth serve as an important mechanism in ductile failures in metals. Particularly, on the micron-level, the extra hardening effect associated with strain gradient is accounted for by adopting strain gradient elasto-plasticity instead of the conventional plasticity. Effects of inertial, strain gradient hardening and thermal softening are formulated analytically for the case where a spherical void expands under external hydrostatic stress. As demonstrated by our results, the inertia effect firstly tends to hinder but then promotes the void growth. The threshold stress required for rapid void growth is lifted due to extra hardening of strain gradient so that the growth of a smaller void is delayed more remarkably. A considerable thermal softening phenomenon is observed here, which is caused by plastic work during the deformation process. The final void growth rate is mainly related to the maximum loading, which is consistent with the prediction based on the classical plastic theory.

16

On some problems in determining tensile parameters of concrete model from size effect tests

Marzec Ireneusz, Bobiński Jerzy

Polish Maritime Research

|

2019

|

nr 2

115--125

EN

The paper presents results of numerical simulations of size effect phenomenon in concrete specimens. The behaviour of in-plane geometrically similar notched and unnotched beams under three-point bending is investigated. In total 18 beams are analysed. Concrete beams of four different sizes and five different notch to depth ratios are simulated. Two methods are applied to describe cracks. First, an elasto-plastic constitutive law with a Rankine criterion and an associated flow rule is defined. In order to obtain mesh independent results, an integral non-local theory is used as a regularisation method in the softening regime. Alternatively, cracks are described in a discrete way within Extended Finite Element Method (XFEM). Two softening relationships in the softening regime are studied: a bilinear and an exponential curve. Obtained numerical results are compared with experimental outcomes recently reported in literature. Calculated maximum forces (nominal strengths) are quantitatively verified against experimental values, but the force – displacement curves are also examined. It is shown that both approaches give results consistent with experiments. Moreover, both softening curves with different initial fracture energies can produce similar force-displacement curves.

17

Influence of pre-tension on torsion of microscale Cu wires: a study via strain gradient theory

Ma Xinbing, Liu Jinxing

Journal of Theoretical and Applied Mechanics

|

2019

|

Vol. 57 nr 4

1055--1065

EN

Nonproportional plastic deformations on the microscale are an emerging topic. A simplified theory of strain gradient elasto-plasticity is developed to study the evolution of yield strength in a copper wire sequentially experiencing tension and torsion. The pre-tension deformation and stress are inherited to the upcoming torsion process, resulting in a nonproportional loading condition. With consideration of the extra hardening effect due to strain gradient, pre-tension weakens the extra hardening effect of the strain gradient and the dependence on the wire radius. Cyclic torsion behavior is also investigated. Anomalous Bauschinger effect and plastic softening are found.

18

An experimental investigation on fracture parameters and brittleness of self-compacting lightweight concrete containing magnetic field treated water

Salehi Hasan, Mazloom Moosa

Archives of Civil and Mechanical Engineering

|

2019

|

Vol. 19, no. 3

803--819

EN

In this study, an experimental research on the fracture parameters of self-compacting lightweight concrete (SCLC) using tap and magnetic water (MW) is presented. For all SCLC mixtures, common fracture parameters were specified by means of both work of fracture method (WFM) and the size effect method (SEM). Three-point bending tests were carried out on 90 notched beams with six mix compositions. The beams were made from mixes with three different water to cement (w/c) ratios of 0.37, 0.47 and 0.52; also, both tap and magnetic water were consumed in the concrete mixes, separately. The results of this research showed that by using MW in SCLC and decreasing w/c ratio from 0.52 to 0.37: (a) both initial fracture energy Gf and total fracture energy GF increased; (b) the fracture toughness and the mechanical properties of SCLC improved. Additionally, the achieved data exhibited that there was a reasonable relation between the total fracture energy obtained by WFM and the initial fracture energy achieved through SEM. The average of GF to Gf ratio in SCLC was 2.70. Furthermore, by using MW in SCLC mixtures, compressive strength, splitting tensile strength and modulus of elasticity increased up to 18%, 9% and 10%, respectively.

19

Carbon nanotubes with controlled length – preparation, characterization and their cytocompatibility effects

Cendrowski K., Jedrzejczak-Silicka M.

Polish Journal of Chemical Technology

|

2018

|

Vol. 20, nr 2

71--79

EN

Multiwalled carbon nanotubes (MWCNTs) have attracted huge attention due to their multifunctionality. Their unique properties allows for covalent and noncovalent modifi cations. The most simple method for functionalization of carbon nanotubes is their decoration with the oxygen containing moieties which can be further simultaneously functionalized for design of new class carriers for targeting and imaging. Here, we present methodology for chopping nanotubes, characterization of MWCNTs, the effect of size on the biocompatibility in culture of L929 mouse fi broblasts using WST-1, LDH and apoptosis assays. The analysis provides the optimal carbon nanotubes length and concentration which can be used for functionalization in order to minimize the effect of the secondary agglomeration when interacting with cells.

20

Badanie efektu skali poprzez modyfikację odcinka pomiarowego próbki przy zginaniu obrotowym oraz ocena wpływu chropowatości

Niesłony A., Agrest D.

Modelowanie Inżynierskie

|

2018

|

T. 36, nr 67

44--48

PL

W artykule przedstawiono zarys historyczny badań nad zjawiskiem efektu skali. Opisane zostały warunki przeprowadzenia prób zmęczeniowych oraz uzyskane wyniki. Otrzymano zauważalny efekt skali podczas próby zginania obrotowego. W pracy przedstawiono także spostrzeżenia dotyczące wpływu wybranych czynników na wyniki badań. Zauważono, że jednym z istotnych czynników jest jakość powierzchni próbek. Przedstawiono wykresy wskazujące na zależność chropowatości powierzchni próbek na ich wytrzymałość podczas próby zginania obrotowego.

EN

The article presents a historical outline of research on the phenomenon of scale effect. The conditions for conducting fatigue tests and the results obtained have been described. A noticeable scale effect was obtained during a rotational bending test. The paper also presents observations regarding the influence of selected factors on test results. It was noted that one of the important factors is the surface quality of the specimen. The graphs show the dependence of the surface roughness of the specimen on their strength during a rotational bending test.