A method of evaluating a residual stress including a condition setting step of setting a processing condition of water jet peening for a processing target; an analysis step of analyzing a jet flow when a fluid is injected from a nozzle model to a processing target model in accordance with the processing condition, and obtaining a void fraction which is a volume fraction of babbles contained in a unit volume of the fluid, and a collapse fraction, which is a volume fraction of the bubbles which collapse in a unit time in the unit volume of the fluid, at each position on a surface of the processing target model; an impact pressure correlation value calculating step of obtaining an impact pressure correlation value, which is a product of the void fraction and the collapse fraction at each position; an experimental value acquisition step of obtaining an impact pressure experimental value.

Nano-indentation test to determine mechanical properties of reservoir rock can be implemented as multi-stage or single-stage tests. An experimental nano-indentation test (multi-stage or single-stage) is performed on a solid sample. A numerical nano-indentation test (multi-stage or single-stage) is performed on a numerical model of the solid sample. One or more experimental force-displacement curves obtained in response to performing the experimental nano-indentation test and one or more numerical force-displacement curves obtained in response to performing the numerical test are compared. Multiple mechanical properties of the solid sample are determined based on a result of the comparing

A steel pipe collapse strength prediction model generation method, a steel pipe collapse strength prediction method, a steel pipe manufacturing characteristics determination method, and a steel pipe manufacturing method capable of highly accurately predicting the collapse strength of a steel pipe after forming or a coated steel pipe in consideration of the pipe-making strain during forming. Into a steel pipe collapse strength prediction model generated by the prediction model generation method, steel pipe manufacturing characteristics including the shape of a steel pipe to be predicted after forming, strength characteristics, and the pipe-making strain are input to predict the collapse strength after forming. Into a steel pipe collapse strength prediction model, steel pipe manufacturing characteristics including the shape of a coated steel pipe to be predicted after forming, strength characteristics, the pipe-making strain, and coating conditions are input to predict the collapse strength of the coated steel pipe.

The invention features a method for determining the worn shape of a deformable body in sliding contact with a deformable substrate. A wear depth w in an inward normal direction is determined at select points on a surface of the deformable body at each point in time t by integration of the following equation:

[00001]$\frac{\mathrm{dw}}{d.Math..Math.\tau }={\mathrm{kT}}_n.Math.v^b$

where k is a material dependent variable determined by physical tests, T.sub.n is a contact pressure determined by finite element analysis of the deformable body in sliding contact with the deformable substrate at each point in time t, v is a constant sliding velocity between the deformable body and the deformable substrate, b is a constant determined by physical tests, and τ=t.sup.b is a computational time.

A joint analyzing method includes: performing a data measurement; performing a detailed analysis; performing a simplified analysis; performing a first repetition analysis in which the detailed analysis is repeated while modifying a first analysis model in which geometry of a joint surrounding region is modeled and an analysis technique in the detailed analysis, until a data measurement result and a detailed analysis result are brought into agreement; and performing a second repetition analysis in which the simplified analysis that takes into consideration an initial internal load of at least one junction in a load non-applied state obtained in the first repetition analysis is repeated while modifying a second analysis model rougher in element division of the geometry than the first analysis model and an analysis technique in the simplified analysis, until the data measurement result and a simplified analysis result are brought into agreement.

A method, apparatus, system, and computer program product for estimating material properties. Training data comprising results of testing samples for a set of materials over a range of loads applied to the samples is identified by a computer system. A machine learning model is trained by the computer system to output the material properties for materials in structures using the training data.

A method to utilize the results from a series of FEM models to develop a master derivative of compliance curve. The use of the unique master curve resolves the test data variability issue caused by fitting the compliance curve individually. The analytically derived derivative of compliance curve eliminates the needs to take the derivative of compliance and therefore the derivative computation error no longer exists. By applying the existing solution and the solution as disclosed and claimed herein to the same set of the raw test data, it is found that data scatter is significantly reduced.

A numerical simulation tool for progressive failure in laminates utilizes a low fidelity approach. The numerical model includes an enriched element that is initially in a low fidelity form. The enriched elements may increase fidelity by splitting locally to simulate an ongoing damage process such as delamination.

A predicting method includes a first step and a second step. The first step includes outputting initial information indicating states of a structure and an object when the object is assembled to the structure, by simulating a process of assembling the object to the structure. The second step includes outputting first prediction information indicating future states of the structure and the object by simulating temporal change of assembly state in which the object is assembled to the structure, using the initial information.

Due to geometric discontinuities introduced by welding and joining processes, stresses or strain cannot be calculated reliably calculated using modern analytical and computer methods as result of stress or strain singularity at joint locations, which leads to severe mesh sensitivity. Design and fatigue evaluation of these structures remain empirical. This disclosure addresses mesh insensitivity of stress/strain calculations for welded structures through a cut-plane traction stress method through a novel post processing of conventional finite element computation results, as well as provides a unified fatigue evaluation procedure for fatigue design and structural life evaluation for both low-cycle and high cycle fatigue regime subjected to either proportional or non-proportional multiaxial fatigue loading, as well as a simple and reliable method for treating spot welds.