Measurement Of Stress Distribution Research Articles

Stress distribution and contact area measurements of a gecko toe using a high-resolution tactile sensor

The adhesive systems of geckos have been widely studied and have been a great source of bioinspiration. Load-sharing (i.e. preventing stress concentrations through equal distribution of loads) is necessary to maximize the performance of an adhesive system, but it is not known to what extent load-sharing occurs in gecko toes. In this paper, we present in vivo measurements of the stress distribution and contact area on the toes of a tokay gecko (Gekko gecko) using a custom tactile sensor with 100 μm spatial resolution. We found that the stress distributions were nonuniform, with large variations in stress between and within lamellae, suggesting that load-sharing in the tokay gecko is uneven. These results may be relevant to the understanding of gecko morphology and the design of improved synthetic adhesive systems.

Semi-nondestructive Measurement of Weld Residual Stress Distribution using Indentation Technique without Reference Load under Non-stressed State according to Measurement Positions

Semi-nondestructive Measurement of Weld Residual Stress Distribution using Indentation Technique without Reference Load under Non-stressed State according to Measurement Positions

Measurement of Internal Stress Distribution to Indivisible Grains of Dual Phase Steel by Energy-dispersive X-ray Diffraction with White X-ray Microbeam

Measurement of Internal Stress Distribution to Indivisible Grains of Dual Phase Steel by Energy-dispersive X-ray Diffraction with White X-ray Microbeam

Measurement of the Internal Stress Distribution to Individual Grains of Dual Phase Steel by Energy-Dispersive X-ray Diffraction with White X-ray Microbeam

Measurement of the Internal Stress Distribution to Individual Grains of Dual Phase Steel by Energy-Dispersive X-ray Diffraction with White X-ray Microbeam

C-23 MEMS 3軸センサを用いた歩行・走行時の足裏応力分布計測(センサ情報によるロコモーション解析)

C-23 MEMS 3軸センサを用いた歩行・走行時の足裏応力分布計測(センサ情報によるロコモーション解析)

Residual Stress Distribution Measurement near the Welding End of an Arc-welding

Residual Stress Distribution Measurement near the Welding End of an Arc-welding

Direct Measurement of the Contact Normal Stress Distribution between Two Smooth Joint Surfaces

The shear strength of rock joints is highly depended upon the failure mode of joint asperity. At lower normal stress slide-up of one asperity up over another mode, however at high normal stress the joint asperities are sheared off at the base. This research uses pressure measurement film to directly measure the contact normal stress between smooth joint surfaces. It demonstrates that the density of color impression is capable of capturing the normal stress distribution behavior. The contact normal stress distribution during shearing is changed. After shearing, the contact stress becomes large. This increase in contact normal stress is to fracture the joint wall material.

Residual Stress Distribution Caused by Laser Hardening and Conventional Quenching in Plain Carbon Steel

Heat transfer during laser hardening occurs from the surface towards the bulk in contrast to conventional quenching, where it occurs from the bulk towards the surrounding. The residual stress distributions due to laser hardening and conventional quenching of plain carbon steel samples were measured using X-ray diffraction. The effect of changing the treatment parameters, that is laser power and feed rate, was examined on the resulting stress distribution. The relationship between the measured stress distribution and the evolved microstructure is established.

Measurement and analysis of internal stress distributions created in gelatin simulated-brain tissue by a pulsed laser-induced liquid jet.

Transsphenoidal surgery is currently employed to treat complex lesions beyond the sella turcica; however, the procedure can be limited by difficulties encountered in dealing with small blood vessels, deep and narrow working spaces, and awkward working angles. To overcome these problems, we have developed a pulsed laser-induced liquid jet system that can dissect tumor tissue while preserving fine blood vessels within deep and narrow working spaces. We have previously evaluated the utility and safety of this procedure. However, the effects of the pulsejet after being injected into the brain are not yet well understood. Especially, the behavior of the stress distribution created by the jet is important because it has recently been reported that high acoustic pressures can affect the brain. In this study, we measured internal stress distributions in a gelatin simulated-brain using photoelasticity experiments. We used a high-speed camera with an image sensor on which an array of micropolarizers was attached to measure the stresses and the shear wave created when the pulsejet enters the simulated brain.

The effect of roughness elements on wind erosion: The importance of surface shear stress distribution

AbstractRepresentation of surface roughness effects on aeolian sediment transport is a key source of uncertainty in wind erosion models. Drag partitioning schemes are used to account for roughness by scaling the soil entrainment threshold by the ratio of shear stress on roughness elements to that on the vegetated land surface. This approach does not explicitly account for the effects of roughness configuration, which may be important for sediment flux. Here we investigate the significance of roughness configuration for aeolian sediment transport, the ability of drag partitioning approaches to represent roughness configuration effects, and the implications for model accuracy. We use wind tunnel measurements of surface shear stress distributions to calculate sediment flux for a suite of roughness configurations, roughness densities, and wind velocities. Roughness configuration has a significant effect on sediment flux, influencing estimates by more than 1 order of magnitude. Measured and modeled drag partitioning approaches overestimate the predicted flux by 2 to 3 orders of magnitude. The drag partition is sensitive to roughness configuration, but current models cannot effectively represent this sensitivity. The effectiveness of drag partitioning approaches is also affected by estimates of the aerodynamic roughness height used to calculate wind shear velocity. Unless the roughness height is consistent with the drag partition, resulting fluxes can show physically implausible patterns. These results should make us question current assessments of the magnitude of vegetated dryland dust emissions. Representing roughness effects on surface shear stress distributions will reduce uncertainty in quantifying wind erosion, enabling better assessment of its impacts and management solutions.

X-Ray diffraction technique applied to study of residual stresses after welding of duplex stainless steel plates

Duplex stainless steel is an example of composite material with approximately equal amounts of austenite and ferrite phases. Difference of physical and mechanical properties of component is additional factor that contributes appearance of residual stresses after welding of duplex steel plates. Measurements of stress distributions in weld region were made by X-ray diffraction method both in ferrite and austenite phases. Duplex Steel plates were joined by GTAW (Gas Tungsten Arc Welding) technology. There were studied longitudinal and transverse stress components in welded butt joint, in heat affected zone (HAZ) and in points of base metal 10 mm from the weld. Residual stresses measured in duplex steel plates jointed by welding are caused by temperature gradients between weld zone and base metal and by difference of thermal expansion coefficients of ferrite and austenite phases. Proposed analytical model allows evaluating of residual stress distribution over the cross section in the weld region.

Inherent-Strain-Based Theory of Measurement of Three-Dimensional Residual Stress Distribution and Its Application to a Welded Joint in a Reactor Vessel

The stress that exists in a body under no external force is called the inherent stress. The strain that is the cause (source) of this stress is called the inherent strain. This study proposes a general theory of an inherent-strain-based measurement method for the residual stress distributions in arbitrary three-dimensional bodies and applies the method to measure the welding residual stress distribution of a welded joint in a reactor vessel. The inherent-strain-based method is based on the inherent strain and the finite element method. It uses part of the released strains and solves an inverse problem by a least squares method. Thus, the method gives the most probable value and deviation of the residual stress. First, the basic theory is explained in detail, and then a concrete measurement method for a welded joint in a reactor vessel is developed. In the method, the inherent strains are unknowns. In this study, the inherent strain distribution was expressed with an appropriate function, significantly decreasing the number of unknowns. Five types of inherent strain distribution functions were applied to estimate the residual stress distribution of the joint. The applicability of each function was evaluated. The accuracy and reliability of the analyzed results were assessed in terms of the residuals, the unbiased estimate of the error variance, and the welding mechanics. The most suitable function, which yields the most reliable result, was identified. The most reliable residual stress distributions of the joint are shown, indicating the characteristics of distributions with especially large tensile stress that may produce a crack.

逆問題解析を援用したコーティング下の応力計測に関する研究

赤外線サーモグラフィを用いた熱弾性応力測定法によって鋼構造物の作用応力を計測する際,塗膜外面温度変動から鋼材表面の温度変動を逆解析的に推定することで塗膜を除去せずにき裂周辺の応力評価を行うことを検討した.

C-12 MEMS3軸力センサを用いた傾斜路歩行時の足裏応力分布計測(身体と環境の計測評価)

C-12 MEMS3軸力センサを用いた傾斜路歩行時の足裏応力分布計測(身体と環境の計測評価)

Measurement of stress distribution for rotating shaft using thermography

Measurement of stress distribution for rotating shaft using thermography

心拍に伴い開閉する大動脈弁の変形が大動脈弁硬化症の発症に及ぼす影響（3次元計測手法による弁膜モデルに生じる応力・歪み分布の測定）

心拍に伴い開閉する大動脈弁の変形が大動脈弁硬化症の発症に及ぼす影響（3次元計測手法による弁膜モデルに生じる応力・歪み分布の測定）

CMOS Sensor Arrays for High Resolution Die Stress Mapping in Packaged Integrated Circuits

This paper reports the design, calibration and application of multiplexed arrays of piezoresistive field-effect transistor stress sensors fabricated in a standard complementary-metal-oxide semiconductor (CMOS) process. Two complementary arrays of 256-current mirror sensor cells provide high spatial density stress mapping with approximately 300 pts/mm2 using only a 1.5 μm process. The arrays are sequentially scanned by an on-chip counter, producing efficient stress measurement, and the sensors resolve normal and shear stresses on the surface of the die with resolution below 1 MPa. The CMOS sensor chips have been used to map stress over a large portion of the die in chip-on-beam and encapsulated chip-on-beam samples, as well as a ceramic dual-in-line package with its cavity filled with underfill material. Finite-element simulation results correlate well with the measured stress distributions. The experimental results from these chips are used to validate finite-element simulation models, and the array designs can be used as subarrays in much larger test chips.

Study on stress birefringence measurement of uniaxial crystal

Residual stress birefringence in crystal will affect frequency conversion efficiency and beam quality. In this paper the distribution characteristic of inherent stress birefringence in uniaxial crystal is analyzed, qualitative results are obtained for KDP crystals by digital stress measurement instrument, and the stress gradient distribution is calculated, also the effect of deviation from optical axis on the measured stress distribution results is discussed. Exact determination of stress birefringence and its spatial distribution is of great importance to the manufacture and application of optical materials and components.

Fatigue tests and design of thin CHS–SHS T-joints under cyclic in-plane bending

Agricultural equipments, such as linkage graders, haymakers, swing-ploughs, bale handlers and road transport equipments, such as road trailers, traffic sign supports and lighting poles are manufactured using welded thin-walled (t < 4 mm) hollow section connections. There are currently no fatigue design rules for nodal joints made up of thicknesses less than 4 mm in existing fatigue design standards such as CIDECT Design Guide No.8. Previous research on welded thin-walled joints covered plate-to-SHS (square hollow section) and SHS-to-SHS T-joints. This paper describes fatigue tests on T-joints made up of thin-walled (t < 4 mm) SHS chords and circular hollow section (CHS) braces, namely CHS–SHS T-joints. The joints were tested under constant stress amplitude cyclic in-plane bending in the brace. In all the 18 CHS–SHS T-joints tested, chord-tension-side failure mode was observed. Using the experimental stress concentration factors (SCFs) obtained through stress distribution measurement at weld toes in the chord and SCFs from existing parametric equations, fatigue design recommendations are proposed.

A Comprehensive Study of SiGe Source/ Drain Local Stress by Nano Beam Diffraction

Compressive stress introduced by source/drain (S/D) SiGe is widely used in 45nm node and beyond advanced technology which boost the P-channel hole mobility. Quantitive measurement of localized stress in channel is limited by the scaling shrinking. Transmitted electron microscopy- Nano Beam Diffraction (TEM-NBD) is an effective method for the local stress distribution measurement in channel and well area derived from S/D Si1-xGex. In this paper, we study the channel strain from the following aspect, including i) active area (AA) width, ii) S/D recess shape, iii) S/D recess trench depth, and iv) Germanium (Ge), Boron (B) concentration of S/D Si1-xGex and Ge, B distribution profile. It is revealed that strain has strong relation with these factors. Pitch with narrow AA width shows lower strain than that of wider AA width. S/D recess shape affects the proximity which is critical for the stress derived from S/D SiGe transmit to channel location. Moreover, S/D recess trench depth determines the volume of filled SiGe then affect the strain to channel. Both of the Ge, B concentration of S/D SiGe and the distribution profile directly affects the lattice mismatch which results in the strain. In general, all these factors affect the volume of the filled SiGe and Ge concentration which eventually determine the strain of S/D to channel area.