CN113886984B - Bolt solid grid modeling and loading method - Google Patents
Bolt solid grid modeling and loading method Download PDFInfo
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- CN113886984B CN113886984B CN202111140251.6A CN202111140251A CN113886984B CN 113886984 B CN113886984 B CN 113886984B CN 202111140251 A CN202111140251 A CN 202111140251A CN 113886984 B CN113886984 B CN 113886984B
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Abstract
The invention belongs to the technical field of bolt grid modeling, and particularly relates to a bolt solid grid modeling and loading method; dividing a bolt finite element model by using a tetrahedral mesh, creating a rigid connecting unit of a constraint point-transmission housing part node, and applying constraint; the TCL language is used for automatically distinguishing the types of the bolts and applying bolt pretightening force: applying loads at corresponding loading points on the transmission shell assembly according to actual working condition loads; exporting the calculation files from the first step to the fourth step through Hypermesh software for simulation analysis of the transmission shell assembly; according to the invention, finite element models of all the same family bolts are obtained by quickly copying one bolt model, and bolt pretightening force is applied by one key; the method is more advanced and irreplaceable than the bolt modeling method and the bolt pretightening force loading method which are disclosed currently.
Description
Technical Field
The invention belongs to the technical field of bolt grid modeling, and particularly relates to a bolt solid grid modeling and loading method.
Background
At present, when various research and development centers analyze parts of a shell assembly, solid grid modeling is performed on bolts in succession. When finite element analysis is carried out on the sealing pressure of the transmission shell in engineering, a real 3D grid model of the connecting bolt of the transmission shell needs to be established, and accurate bolt pretightening force is applied. Generally, the number of the connecting bolts of one transmission housing assembly is (20-40). The universal method for applying bolt pretightening force is to manually establish a bolt grid model and manually apply the bolt pretightening force. A method of modeling a solid bolt grid as described in the prior art: the method comprises the steps of dividing a pentahedral grid and a hexahedral grid to obtain a finite element model of a bolt, calculating bolt pretightening force according to the grade and the diameter of the bolt, manually applying a load, manually establishing a load acting surface and a load acting point and manually associating the load acting surface and the load acting point, wherein the operation process is complicated and repeated, a large amount of time is consumed, and errors are easy to occur.
Disclosure of Invention
In order to overcome the problems, the invention provides a bolt solid grid modeling and loading method, a tetrahedral grid is adopted to divide a bolt finite element model, the finite element models of all the same family bolts are obtained by quickly copying one bolt model, and bolt pretightening force is applied by one key; the method is more advanced and irreplaceable than the bolt modeling method and the bolt pretightening force loading method which are disclosed currently.
A bolt solid grid modeling and loading method comprises the following steps:
step one, establishing a finite element model of a transmission shell assembly, a gear shaft and a bearing used on the transmission shell assembly in Hypermesh software, and then establishing a finite element model of all bolts used on the transmission shell assembly by adopting TCL language;
step two, creating a rigid connecting unit of a constraint point-transmission housing part node, and applying constraint;
step three, automatically distinguishing the bolt models by applying TCL language and applying bolt pretightening force:
firstly, automatically creating a bolt pretightening force loading point by applying a TCL language;
secondly, applying TCL language to automatically apply bolt pretightening force;
thirdly, automatically creating a bolt pre-tightening surface by applying TCL language;
automatically associating the bolt pretightening force loading point, the pretightening surface and the pretightening force applied at the bolt pretightening force loading point by using a TCL language;
fifthly, a step of automatically creating bolt pre-tightening load by applying TCL language;
step four, applying the sealing pressure calculation load of the transmission shell assembly in Hypermesh software: applying loads at corresponding loading points on the transmission shell assembly according to actual working condition loads;
and step five, exporting the calculation files from the step one to the step four through Hypermesh software for simulation analysis of the transmission shell assembly.
The specific process of the step one is as follows:
inputting a geometric model of a transmission shell assembly into Hypermesh software, and establishing a finite element model of the geometric model;
inputting geometric models of all bolts used on the transmission shell assembly into Hypermesh software, firstly establishing a finite element model of a certain bolt, then establishing finite element models of all bolts in the same group with the bolt by applying TCL (tool control language), and repeatedly establishing finite element models of other bolts in the same group so as to establish finite element models of all bolts;
inputting a geometric model of a gear shaft and a bearing used on the transmission shell assembly into Hypermesh software, and establishing a finite element model of the gear shaft and the bearing;
fourthly, defining the material properties of the part:
defining the transmission shell assembly as an aluminum material, and defining the elastic modulus of the material as 74000MPa and the Poisson ratio as 0.3; defining the bolt, the gear shaft and the bearing as steel, and defining the elastic modulus of the material as 2.1e5 MPa and the Poisson ratio as 0.3;
fifthly, defining a contact relation:
defining the contact relation between the nut part of the bolt and the contact surface of the transmission shell assembly, and the friction coefficient is 0.1; defining the contact relation between the screw part of the bolt and the bolt hole on the transmission shell assembly, and the friction coefficient is 0.1; the rest adjacent contact surfaces of the transmission shell assembly are defined to be in contact relation, and the friction coefficient is 0.1.
The method specifically comprises the following steps of establishing a finite element model of the bolt in the first step:
step a, grouping all bolts according to the diameter of a screw, grouping the bolts with the same diameter into a group, and naming the bolts according to the diameter of the screw;
b, taking out a geometric model of any bolt in Hypermesh software, and cutting the screw into an upper closed body and a lower closed body at the position, which is smaller than the thickness of the first 4 of the connected piece, of the screw by using a plane vertical to the screw; the geometry of an upper closing body and a lower closing body is divided by a tetrahedral grid, the upper closing body and the lower closing body share all nodes of a cutting surface, a screw part is the same as the grid nodes of a bolt hole on a transmission shell assembly, and the upper closing body and the lower closing body are named as bolt1_ M8_1 and bolt1_ M8_2 respectively;
step c, calling a createbestcictrecenternode lines command by applying a TCL language to obtain the central point of the bottom of the screw of the bolt;
d, calling a createlistpanel nodes command to sequentially designate the grid model of the bolt, namely the position of the finite element model, and the positions of the other bolts to be modeled, which are taken out in the step b;
step e, calling a dual task mark elements command and a translatemark elements command to once establish a finite element model of all the bolts in the same group as the bolts taken out in the step b;
and f, repeating the steps b-e for other groups of bolts of different groups of bolts taken out in the step b, and establishing finite element models of all the bolts.
The connected piece I4 in the step b is a part close to the nut in the two parts fixed by the bolt.
The plane perpendicular to the screw rod for cutting the bolt in the step b is a bolt cutting surface 3.
The specific process of the second step is as follows:
firstly, creating a rigid connecting unit at a bolt hole for connecting with an engine on a transmission shell assembly;
second, the 1-6 directional degrees of freedom of the link unit are constrained at the rigid link unit.
The concrete process of automatically distinguishing the types of the bolts and applying the pretightening force of the bolts by applying the TCL language in the third step is as follows:
firstly, automatically creating a bolt pretightening force loading point:
A. calling a createmark nodes command to take out the nodes on the upper half part of the bolt and place the nodes in nodes1, and take out the nodes on the lower half part of the bolt and place the nodes in nodes 2;
B. calling a marktersection nodes 1nodes 2 command to obtain a node set of a bolt cutting surface 3, and placing the node set in nodes 1;
C. calling a createbestcyclic electrode nodes command to obtain a central point O of a 3 node of a bolt cutting surface, wherein the point O is used as a loading point of bolt pretightening force;
secondly, applying TCL language to automatically apply bolt pretightening force:
A. editing a window program by adopting a TCL/TK language, and writing a bolt pretightening force calculation formula into the program: f ═ M/kD, where D is the diameter of the screw; k is set as an input box capable of being modified, the initial default value is 0.2, and M is the tightening torque of the bolt;
B. calling a loadcreationentry _ current sets command, and applying corresponding bolt pretightening force to the loading points of all bolt pretightening forces at one time;
thirdly, automatically creating a bolt pre-tightening surface by applying TCL language:
A. calling the findfaces components command to obtain a surface unit of the upper half part of the bolt; applying a createmark elements 1 'by comp' or 'faces' command to place a surface element in the elements 1;
B. calling findmark elements 111 nodes 01 command to obtain all nodes of the surface unit of the upper half part of the bolt, and placing the nodes in nodes 1;
C. calling a hm _ measuredstartdistance command to find out a point N closest to a central point O of a node 3 of the bolt cutting surface in nodes1, and placing the point N in nodes 2;
D. calling a findmark nodes 211 elements 02 command to find grid cells around the N points, and placing the grid cells in elements 2;
E. calling a marking section elements 1 elements 2 command to acquire a grid unit closest to a central point O on a bolt cutting surface 3;
F. calling an open search elements 1 'by face' command to obtain all grid cells of the bolt cutting surface 3;
G. calling an interface command to create a bolt pre-tightening surface;
and fourthly, automatically associating the bolt pretightening force loading point, the pretightening surface and the pretightening force applied at the bolt pretightening force loading point by applying a TCL language:
invoking the bictiononyloyad groups and the attributeupdateint groups to correlate the bolt pretightening force loading points, the bolt pretightening surfaces and the pretightening forces applied at the bolt pretightening force loading points of the same bolt;
fifthly, automatically creating bolt pre-tightening load by applying TCL language:
and calling a loadstepcreate command to automatically create a bolt pre-tightening load step.
The upper half part of the bolt is the part of the bolt above the cutting surface 3 of the bolt, and the lower half part of the bolt is the part of the bolt below the cutting surface 3 of the bolt.
Compared with the prior art, the invention has the beneficial effects that:
firstly, when a bolt grid model is created by a general method, 1 bolt grid model needs to be established first, then two points are given, and a 2 nd bolt grid model is created by a copying and moving method. Then two points are given, the 3 rd bolt grid model … … is created by a copying and moving method, and the process is circulated until all the required bolt grid models are created, and at least 200 times of manual operation are needed; according to the invention, all bolt grid models can be quickly created 1 time by identifying the bolt position, so that a large amount of labor cost is saved;
secondly, when the bolt pre-tightening force is applied by the general method, 1 load action point needs to be established, then 1 load action surface is established in the bolt, and then the load action point, the load action surface and the load are associated to complete the pre-tightening force application process of 1 bolt. Then, a 2 nd load action point is established, a 2 nd load action surface is established, the load action point and the action surface of the 2 nd bolt are related, and the load … … is cyclically operated for at least 600 times to finish the load application on all the bolts; according to the invention, the bolt load action point, the action surface and the load can be automatically established through a set rule, and are automatically associated, so that the application of the pretightening force of any number of bolts can be quickly and accurately realized;
thirdly, when the bolt load is applied by the general method, manually calculating the bolt pretightening force F according to a formula M (kFD), and applying the pretightening force F to the load action points of the bolts; the invention can automatically calculate the pretightening force of the bolt according to the input bolt tightening torque and quickly apply the pretightening force to each bolt.
Therefore, the method has the advantages of standardizing the operation process, standardizing the calculation method, quickly carrying out bolt entity grid modeling and applying bolt pretightening force, and is beneficial to avoiding the non-standardization of manual operation, reducing result errors caused by human factors, improving the simulation precision, shortening the research and development period and reducing the research and development cost.
Drawings
FIG. 1 is a schematic modeling of a transmission housing of the present invention.
Fig. 2 is a schematic view of the bolt structure of the present invention.
FIG. 3 is a schematic of the bolt modeling of the present invention.
Wherein: 1-transmission front shell 1; 2-a transmission rear housing; 3-cutting the bolt; 4-connected piece one; and 5-connected part II.
Detailed Description
For clearly and completely describing the technical scheme and the specific working process thereof, the specific implementation mode of the invention is as follows by combining the drawings in the specification:
in the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature "under," "beneath," and "under" a second feature may be directly under or obliquely under the second feature, or may simply mean that the first feature is at a lesser elevation than the second feature.
In the description of the specification, reference to the description of "one embodiment," "some embodiments," "an example," "a specific example," or "some examples" or the like means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Example 1
A bolt solid grid modeling and loading method comprises the following steps:
as shown in fig. 1-3, step one, establishing a finite element model of the transmission housing assembly, the gear shaft and the bearing used on the transmission housing assembly in Hypermesh software, and then establishing a finite element model of all bolts used on the transmission housing assembly by adopting TCL language;
step two, creating a rigid connecting unit of a constraint point-transmission housing part node, and applying constraint;
step three, automatically distinguishing the bolt models by applying TCL language and applying bolt pretightening force:
firstly, automatically creating a bolt pretightening force loading point by applying a TCL language;
secondly, applying TCL language to automatically apply bolt pretightening force;
thirdly, automatically creating a bolt pre-tightening surface by applying TCL language;
automatically associating the bolt pretightening force loading point, the pretightening surface and the pretightening force applied at the bolt pretightening force loading point by applying a TCL language;
fifthly, a step of automatically creating bolt pre-tightening load by applying TCL language;
step four, applying the sealing pressure calculation load of the transmission shell assembly in Hypermesh software: applying loads at corresponding loading points on the transmission shell assembly according to actual working condition loads;
and step five, exporting the calculation files from the step one to the step four through Hypermesh software for simulation analysis of the transmission shell assembly.
The upper half part of the bolt is a bolt part above the bolt cutting surface 3, and the lower half part of the bolt is a bolt part below the bolt cutting surface 3.
The specific process of the step one is as follows:
firstly, inputting a geometric model of a transmission shell assembly, namely a transmission front shell 1 and a transmission rear shell 2, into Hypermesh software, and establishing a finite element model of the transmission front shell 1 and the transmission rear shell 2 in the Hypermesh software;
inputting geometric models of all bolts used on the transmission shell assembly into Hypermesh software, firstly establishing a finite element model of one bolt, then applying TCL language to establish finite element models of all bolts in the same group with the bolt, and repeatedly establishing finite element models of other bolts in the same group, thereby establishing finite element models of all bolts;
inputting geometric models of a gear shaft and a bearing used on the transmission shell assembly into Hypermesh software, and establishing finite element models of the gear shaft and the bearing in the Hypermesh software;
fourthly, defining the material properties of the part:
defining a transmission shell assembly as aluminum material in Hypermesh software, and defining the elastic modulus of the material as 74000MPa and the Poisson ratio as 0.3; defining the bolt, the gear shaft and the bearing as steel, and defining the elastic modulus of the material as 2.1e5 MPa and the Poisson ratio as 0.3;
fifthly, defining a contact relation:
defining the contact relation between the nut part of the bolt and the contact surface of the transmission shell assembly in Hypermesh software, wherein the friction coefficient is 0.1; defining the contact relation between the screw part of the bolt and the bolt hole on the transmission shell assembly, and the friction coefficient is 0.1; defining other adjacent contact surfaces of the transmission shell assembly to be in contact relation, wherein the friction coefficient is 0.1, the contact surfaces comprising the gear shaft and the bearing are in contact relation, and the friction coefficient is 0.1; the bearing is in contact relation with the contact surface of the transmission shell assembly, and the friction coefficient is 0.1.
The method specifically comprises the following steps of establishing a finite element model of the bolt in the first step:
step a, grouping all bolts according to the diameter of a screw, grouping the bolts with the same diameter into a group, and naming the bolts according to the diameter of the screw; the length of the screw is considered according to the situation in the actual operation process;
b, taking bolts with the diameter of 8mm as an example, taking out a geometric model of any bolt by Hypermesh software, and cutting the screw into an upper closed body and a lower closed body at the position, on the screw, of which the thickness is less than 4 of the thickness of the connected piece, of the plane vertical to the screw; the geometry of an upper part closing body and a lower part closing body is divided by a tetrahedral mesh, the upper part closing body and the lower part closing body share all nodes of a cutting surface, a screw part is the same as the mesh nodes of bolt holes on a transmission shell assembly, and the upper part closing body and the lower part closing body are named as bolt1_ M8_1 and bolt1_ M8_2 respectively;
step c, calling a createbestcictrecenternode lines command by using a TCL language to obtain the central point of the bottom of the screw of the bolt;
d, calling a createlistpanel nodes command to sequentially designate the grid model of the bolt taken out in the step b, namely the position of the finite element model and the positions of the other bolts to be modeled;
step e, calling a dual task mark elements command and a translatemark elements command to once establish a finite element model of all the bolts in the same group as the bolts taken out in the step b;
and f, repeating the steps b-e for other groups of bolts of different groups of bolts taken out in the step b, and establishing finite element models of all the bolts.
The connected piece I4 in the step b is a part close to the nut in the two parts fixed by the bolt.
The plane perpendicular to the screw rod for cutting the bolt in the step b is a bolt cutting surface 3.
The specific process of the second step is as follows:
firstly, creating a rigid connecting unit at a bolt hole on a transmission shell assembly for connecting with an engine;
second, the 1-6 directional degrees of freedom of the link unit are constrained at the rigid link unit.
The concrete process of automatically distinguishing the types of the bolts and applying the pretightening force of the bolts by applying the TCL language in the third step is as follows:
firstly, automatically creating a bolt pretightening force loading point:
A. calling a createmark nodes command in Hypermesh software to take out the nodes on the upper half part of the bolt and place the nodes in nodes1, and taking out the nodes on the lower half part of the bolt and place the nodes in nodes 2;
B. calling a marktersection nodes 1nodes 2 command to obtain a node set of a bolt cutting surface 3, and placing the node set in nodes 1;
C. calling a createbestcyclic electrode nodes command to obtain a central point O of a 3 node of a bolt cutting surface, wherein the point O is used as a loading point of bolt pretightening force;
secondly, applying TCL language to automatically apply bolt pretightening force:
A. editing a window program by adopting a TCL/TK language, and writing a bolt pretightening force calculation formula into the program: f ═ M/kD, where D is the diameter of the screw (since the bolt designation is named in terms of the screw diameter of the bolt, the Hypermesh software is able to directly obtain the D value from the bolt designation); k is set as an input box capable of being modified, the initial default value is 0.2, and M is the tightening torque of the bolt;
the pre-tightening force of all bolts can be calculated at one time by inputting the tightening torque M of the bolts of different types;
B. calling a loadcreationentry _ current sets command, and applying corresponding bolt pretightening force to the loading points of all bolt pretightening forces at one time;
thirdly, automatically creating a bolt pre-tightening surface by applying TCL language:
A. calling the findfaces components command to obtain a surface unit of the upper half of the bolt (i.e., the outer surface of the upper half of the bolt); applying a createmark elements 1 'by comp' or 'faces' command to place a surface element in the elements 1;
B. calling findmark elements 111 nodes 01 command to obtain all nodes of the surface unit of the upper half part of the bolt, and placing the nodes in nodes 1;
C. calling a hm _ measurecholocation command to find out a point N closest to a central point O of a node of a bolt cutting surface 3 in nodes1, and placing the point N in nodes 2;
D. calling a findmark nodes 211 elements 02 command to find grid elements in the bolt finite element model around the N point, and placing the grid elements in elements 2;
E. calling a marking section elements 1 elements 2 command to acquire a grid unit closest to a central point O on a bolt cutting surface 3;
F. calling an open search elements 1 'by face' command to obtain all grid cells of the bolt cutting surface 3;
G. invoking an interrupt command to create a bolt pre-tightening surface;
and fourthly, automatically associating the bolt pretightening force loading point, the pretightening surface and the pretightening force (load) applied at the bolt pretightening force loading point by applying the TCL language:
invoking the bictiononyloyad groups and the attributeupdateint groups to correlate the bolt pretightening force loading points, the bolt pretightening surfaces and the pretightening force (load) applied at the bolt pretightening force loading points of the same bolt;
fifthly, automatically creating bolt pre-tightening load by applying TCL language:
the loadstepcreate command is invoked to automatically create a bolt pretension load step.
As shown in fig. 2, the upper part of the bolt refers to the part of the bolt above the bolt cutting surface 3, and the lower part of the bolt refers to the part of the bolt below the bolt cutting surface 3.
Example 2
In a first step, as shown in fig. 1, a finite element model for assembling a transmission shell assembly is established:
1) finite element models such as a transmission front shell 1, a transmission rear shell 2 and the like are established in Hypermesh software.
2) Establishing a transmission shell assembly bolt 3 finite element model in Hypermesh software:
firstly, grouping all bolts according to the diameter and the length of a screw;
and taking a bolt with the diameter of 8mm as an example, taking out a geometric model of any bolt, and cutting the bolt into an upper closed body and a lower closed body at the position, which is smaller than the thickness of the part to be connected by 4, on the bolt by using a plane vertical to the bolt. The upper part and the lower part are geometrically divided by a tetrahedral mesh, the two parts share all nodes of a cutting surface, and the screw part is the same as the mesh nodes of the bolt holes of the transmission shell. The upper and lower parts are named bolt1_ M8_1 and bolt1_ M8_2 respectively;
calling a createbestcictrecenternode lines command by using a TCL language to obtain the central point of the bottom of the screw of the bolt;
invoking a createlistpanel nodes command to sequentially designate the positions of the bolt grid model and the positions of the other bolts to be modeled;
calling duplicate mark elements and translatemaster elements to create all the same family bolt grid models at one time;
sixthly, repeating the rest bolt groups in the assembly model to the fifth step to establish the finite element model of all the bolts.
3) Defining part material properties: the transmission shell is made of aluminum, the elastic modulus of the material is 74000MPa and the Poisson ratio is 0.3 in the pre-processing software; the bolts, gear shafts, bearings and the like are made of steel, the elastic modulus of the material is defined to be 2.1e5 MPa in the preprocessing software, and the Poisson ratio is 0.3.
4) Defining a transmission housing assembly contact relationship: defining the contact relation between the bolt nut part and the contact surface of the transmission shell, and the friction coefficient is 0.1; defining the contact relation between the bolt screw part and the bolt hole of the transmission shell, and the friction coefficient is 0.1; the rest adjacent contact surfaces are defined to be in contact relation, and the friction coefficient is 0.1.
Second, a constraint point-transmission case part node connection unit is created, and a constraint is applied:
1) creating a connection unit where the transmission housing requires restraint;
2) constraints are imposed at the connection unit.
Thirdly, automatically distinguishing the types of the bolts by applying a TCL language and applying bolt pretightening force:
1) automatically creating a bolt pretightening force loading point:
calling a createmark nodes command to take out partial nodes on the bolt and put the partial nodes in nodes1, and taking out partial nodes on the bolt and putting the partial nodes in nodes 2;
secondly, calling a marktersection nodes 1nodes 2 command to obtain a node set of the bolt cutting surface 3, and placing the node set in nodes 1;
and thirdly, acquiring the center O of the cutting surface node by calling an original probe test cyclic electrode nodes command, wherein the O point is used as a loading point of the bolt pretightening force.
2) Applying TCL language to automatically apply bolt pretightening force:
firstly, editing a window program by using a TCL/TK language, and writing a bolt pretightening force calculation formula into the program: f is M/kD, wherein D is automatically recorded according to a bolt naming rule; k is set as an input box which can be modified, and the initial default value is 0.2;
secondly, the pre-tightening force of all the bolts can be calculated at one time by inputting the tightening torque M of the bolts with different types;
and invoking the loadcreatementationity _ current sets command to apply the bolt pretightening force once.
3) The bolt pretensioning face is automatically created by applying TCL language:
calling a findfaces components command to acquire a surface unit of the upper half part of the bolt; applying a createmark elements 1 'by comp' and 'faces' command to place a face unit in the elements 1;
invoking a findmark elements 111 nodes 01 command to acquire all nodes of the upper half part of the surface unit of the bolt, and placing the nodes in nodes 1;
calling a hm _ measurortdistance command to find out a point N which is closest to a central O point in nodes1, and placing the point N in nodes 2;
invoking a findmark nodes 211 elements 02 command to find grid cells around the N point, and placing the grid cells in elements 2;
invoking a Markotentersection elements 1 elements 2 command to obtain the grid unit closest to the midpoint on the bolt cutting surface 3;
obtaining all grid units of the bolt cutting surface 3 by calling an apppendmark elements 1 'by face' command;
and creating a bolt pre-tightening surface by calling the interface command.
4) The TCL language is used for automatically associating bolt pretightening force loading points, pretightening surfaces and loads:
and the bolt pretightening force loading point, the pretightening surface and the load can be automatically associated by calling the bictionloadage groups and the attabutedupatenint groups.
5) And (3) automatically creating bolt pre-tightening load by applying TCL language:
and calling a loadstepcreate command to automatically create a bolt pre-tightening load step.
And fifthly, applying a sealing pressure of the transmission shell to calculate the load: and applying the load at the corresponding load point according to the actual working condition load.
And sixthly, submitting calculation: and exporting the calculation file and submitting the calculation.
Although the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, the scope of the present invention is not limited to the specific details of the above embodiments, and any person skilled in the art can substitute or change the technical solution of the present invention and its inventive concept within the technical scope of the present invention, and these simple modifications belong to the scope of the present invention.
It should be noted that, in the above embodiments, the various features described in the above embodiments may be combined in any suitable manner, and in order to avoid unnecessary repetition, the present invention does not separately describe various possible combinations.
In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.
Claims (8)
1. A bolt solid grid modeling and loading method is characterized by comprising the following steps:
step one, establishing a finite element model of a transmission shell assembly, a gear shaft and a bearing used on the transmission shell assembly in Hypermesh software, and then establishing a finite element model of all bolts used on the transmission shell assembly by adopting TCL language;
step two, creating a rigid connecting unit of a constraint point-transmission housing part node, and applying constraint;
step three, automatically distinguishing the bolt models by applying TCL language and applying bolt pretightening force:
firstly, automatically creating a bolt pretightening force loading point by applying a TCL language;
secondly, applying TCL language to automatically apply bolt pretightening force;
thirdly, automatically creating a bolt pre-tightening surface by applying TCL language;
automatically associating the bolt pretightening force loading point, the pretightening surface and the pretightening force applied at the bolt pretightening force loading point by applying a TCL language;
fifthly, a step of automatically creating bolt pre-tightening load by applying TCL language;
step four, applying the sealing pressure calculation load of the transmission shell assembly in Hypermesh software: applying loads at corresponding loading points on the transmission shell assembly according to actual working condition loads;
and step five, exporting the calculation files from the step one to the step four through Hypermesh software for simulation analysis of the transmission shell assembly.
2. The method for modeling and loading a bolt solid grid according to claim 1, wherein the specific process of the first step is as follows:
inputting a geometric model of a transmission shell assembly into Hypermesh software, and establishing a finite element model of the geometric model;
inputting geometric models of all bolts used on the transmission shell assembly into Hypermesh software, firstly establishing a finite element model of one bolt, then applying TCL language to establish finite element models of all bolts in the same group with the bolt, and repeatedly establishing finite element models of other bolts in the same group, thereby establishing finite element models of all bolts;
inputting a geometric model of a gear shaft and a bearing used on the transmission shell assembly into Hypermesh software, and establishing a finite element model of the gear shaft and the bearing;
fourthly, defining the material property of the part:
defining the transmission shell assembly as an aluminum material, and defining the elastic modulus of the material as 74000MPa and the Poisson ratio as 0.3; defining the bolt, the gear shaft and the bearing as steel materials, and defining the elastic modulus of the material as 2.1e5 MPa and the Poisson ratio as 0.3;
fifthly, defining a contact relation:
defining the contact relation between the nut part of the bolt and the contact surface of the transmission shell assembly, and the friction coefficient is 0.1; defining the contact relation between the screw part of the bolt and the bolt hole on the transmission shell assembly, and the friction coefficient is 0.1; the rest adjacent contact surfaces of the transmission shell assembly are defined to be in contact relation, and the friction coefficient is 0.1.
3. The bolt solid grid modeling and loading method according to claim 2, wherein the step one of establishing the finite element model of the bolt specifically comprises the following steps:
step a, grouping all bolts according to the diameter of a screw, grouping the bolts with the same diameter into a group, and naming the bolts according to the diameter of the screw;
b, calling a geometric model of any bolt in Hypermesh software, and cutting the screw into an upper closed body and a lower closed body at the position, on the screw, of which the thickness is less than 4 of the thickness of the connected piece, of the plane vertical to the screw; the geometry of an upper part closing body and a lower part closing body is divided by a tetrahedral mesh, the upper part closing body and the lower part closing body share all nodes of a cutting surface, a screw part is the same as the mesh nodes of bolt holes on a transmission shell assembly, and the upper part closing body and the lower part closing body are named as bolt1_ M8_1 and bolt1_ M8_2 respectively;
step c, calling a createbestcictrecenternode lines command by using a TCL language to obtain the central point of the bottom of the screw of the bolt;
d, calling a createlistpanel command to sequentially designate the grid model of the bolt taken out in the step b, namely the position of the finite element model and the positions of the other bolts to be modeled;
step e, calling a dual task mark elements and a translatemark elements command to once establish a finite element model of all the bolts in the same family as the bolts taken out in the step b;
and f, repeating the steps b-e for other types of bolts of different groups and types of bolts taken out in the step b, and establishing finite element models of all the bolts.
4. The method as claimed in claim 3, wherein the connected component (4) in step b is a nut-near component of two components fixed by bolts.
5. The method for modeling and loading a bolt solid grid according to claim 4, wherein the plane perpendicular to the screw rod for cutting the bolt in step b is a bolt cutting plane (3).
6. The method for modeling and loading a bolt solid grid according to claim 5, wherein the specific process of the second step is as follows:
firstly, creating a rigid connecting unit at a bolt hole on a transmission shell assembly for connecting with an engine;
second, the 1-6 directional degrees of freedom of the link unit are constrained at the rigid link unit.
7. The method for modeling and loading the physical grid of the bolt according to claim 6, wherein the TCL language applied in the third step is used for automatically distinguishing the types of the bolt and applying the pretightening force of the bolt as follows:
firstly, automatically creating a bolt pretightening force loading point:
A. calling a createmark nodes command to take out the nodes of the upper half part of the bolt and place the nodes into nodes1, and taking out the nodes of the lower half part of the bolt and place the nodes into nodes 2;
B. calling a marktersection nodes 1nodes 2 command to obtain a node set of a bolt cutting surface (3), and placing the node set in nodes 1;
C. calling a createbestcyclic electrode nodes command to obtain a central point O of a node of a bolt cutting surface (3), wherein the point O is used as a loading point of bolt pretightening force;
secondly, applying TCL language to automatically apply bolt pretightening force:
A. editing a window program by adopting a TCL/TK language, and writing a bolt pretightening force calculation formula into the program: f ═ M/kD, where D is the diameter of the screw; k is set as an input box capable of being modified, the initial default value is 0.2, and M is the tightening torque of the bolt;
B. calling a loadcreatementationjcurvesets command, and applying corresponding bolt pretightening force to the loading points of all bolt pretightening forces at one time;
thirdly, automatically creating a bolt pre-tightening surface by applying TCL language:
A. calling the findfaces components command to obtain a surface unit of the upper half part of the bolt; applying a createmark elements 1 'by comp' or 'faces' command to place a surface element in the elements 1;
B. calling findmark elements 111 nodes 01 command to obtain all nodes of the surface unit of the upper half part of the bolt, and placing the nodes in nodes 1;
C. calling a hm _ measuredstartdistance command to find out a point N closest to a central point O of a node of a bolt cutting surface (3) in nodes1, and placing the point N in nodes 2;
D. calling a findmark nodes 211 elements 02 command to find grid cells around the N point, and placing the grid cells in elements 2;
E. calling a marking section elements 1 elements 2 command to acquire a grid unit closest to a central point O on a bolt cutting surface (3);
F. calling an open tag elements 1 'by face' command to obtain all grid cells of a bolt cutting surface (3);
G. calling an interface command to create a bolt pre-tightening surface;
and fourthly, automatically associating the bolt pretightening force loading point, the pretightening surface and the pretightening force applied at the bolt pretightening force loading point by applying a TCL language:
invoking the bictiononylload groups and the attenbutional update groups to correlate the bolt pretightening force loading point, the bolt pretightening surface and the pretightening force applied at the bolt pretightening force loading point of the same bolt;
fifthly, automatically creating a bolt pre-tightening load step by applying TCL language:
and calling a loadstepcreate command to automatically create a bolt pre-tightening load step.
8. The bolt solid grid modeling and loading method according to claim 7, wherein the upper part of the bolt is a bolt part above a bolt cutting surface (3), and the lower part of the bolt is a bolt part below the bolt cutting surface (3).
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